CurlChemist

There has been a lot of buzz in the beauty trenches the past year or so about the new product line released by a newcomer to the personal care product industry, Living Proof. The academic pedigrees, business experience, and sheer intellectual prowess of the founding minds and in-house research team of this start-up is nothing short of dizzying, especially when one considers the size of the company. The board is composed of a brilliant team of scientists from MIT, investors and idea generators from Polaris Venture Partners, and two extremely talented and experienced stylists.

Living Proof co-founder Jon Flint (partner in Polaris Venture Partners) has a passion for investing in and developing new business ventures in all areas of technology and consumer products. He is always on the lookout for new ideas. Conversations held with prominent stylists Ward Stegerhoek and Mitch DeRosa about the current state of haircare and skincare products led to the inception of the concept of Living Proof. Their vision was to assemble a multidisciplinary team of scientists from the medical, chemical, and biotechnical fields to work in concert with top stylists to develop truly innovative products for skin and hair.

None of the scientists who were part of the original team had any experience in the personal care product development industry, but were all extremely prestigious in their own areas of expertise. Although this is stated nowhere overtly in the Living Proof literature, I believe this was purposeful, as their goal was to approach product development from a foundational, molecular level with a specific goal, and to do so without any of the baggage that might be associated with a common formulator mindset of, “but this is how you must design a hair conditioner, because this is how everyone designs a conditioner.”

Breakthrough

The goal of the research and development team was to develop a truly novel product that would work to help control the universal problem of frizzy hair, especially in humid conditions. In order to have smooth locks, it is essential to have a hair product that will seal the cuticle of the hair shaft in order to prevent water from passing into and out of the hair. The product must be able to accomplish this task without weighing the hair down or making it greasy. (For more detailed information on hair, humidity, and frizz, review these relevant articles. Humidity, Humectants, and the Hair, Dew Point, Porosity)

People have relied upon oils and serums throughout history to tame their tresses, but have had to deal with greasy, unpleasant feeling hair that may have even still been frizzy. Many of these products were made of plant oils, animal fats, mineral oil, or fatty alcohols. Silicone oils were a revolutionary discovery in the latter half of the twentieth century, and became the go-to ingredient for anti-frizz serums and products. However, even these space-age polymers were not without drawbacks. Many consumers found themselves dealing with hair that became increasingly more unruly, lank, greasy, and even dry. This is especially the case for curly haired consumers, whose delicate locks seem to be particularly susceptible to the limitations of silicone polymers.

The scientists at Living Proof reasoned that one of the limitations of silicone polymers in hair care applications is their relatively large molecular size. These large molecules sit on the surface of the hair, can attract dirt and particles, and weigh the hair down. For this reason, it is recommended that silicone serums and products containing silicones be used in relatively small amounts. However, this becomes a drawback itself, as there ends up being incomplete coating of the hair by the silicone, and thus some hair strands are left vulnerable to the problems of ruffled cuticle, frizz, and tangling caused by exposure to humidity.

It became clear that in order to be truly on the cutting edge, it would be necessary to develop an entirely new kind of polymer that could conquer the problem of frizz by coating the entire surface of all of the hair, but that would not create its own set of problems. After a year of intensive laboratory and literature research, the Living Proof scientists discovered the polymer they call “PolyfluoroEster.” Development of products based on this new polymer and field testing on real users gave the company the feedback it needed: They had a product that demonstrated real improvement over silicone-based anti-frizz products!

PolyfluoroEster, the little polymer that could

The self-purported magical component of the Living Proof line of hair products is a polymer only disclosed as “polyfluoroester”, which is fairly non-specific in terms of revealing the actual molecular structure to us. The organization is understandably extremely protective of their intellectual property, as keeping the secret ingredient under wraps will help maintain their advantage in the competitive beauty products market. However, the CurlChemist has been digging in the trenches to discover what she can, so we can make some educated guesses about its structure, how that might affect its performance on our hair, and what sorts of expectations we can have for these products.

So what is it? Well, the short answer is that it is a modified fluoropolymer, which is a synthetic polymer made up of the typical carbon-based backbone, but with fluorine molecules either attached directly onto the backbone of the polymer or suspended from the sides of the chain as substituents. The fluoropolymer most consumers are familiar with is Teflon, or poly(tetrafluoroethylene).

Molecular structure of Teflon (PTFE)

PTFE, or Teflon, is prized for its unique chemical and thermal stability, its extremely low coefficient of friction, as well as its ability to act as both a water and oil repellent. It is truly “non-stick.” However, one limitation is its extremely high molecular weight (too heavy for hair), and another is its complete insolubility in virtually any solvent, including water. For these reasons (and others), polymer scientists have experimented over the years with many variants of this molecule, using different monomers and different combinations of monomers to create modified fluoropolymers and copolymers as well (polymers synthesized using mixtures of different monomers). There are companies who market fluorinated reactive surfactants as well.

Molecular structure of a fluorinated copolymer

Armed with all of this information, my best educated guess is that this PolyfluoroEster is possibly a fluorinated polyester (a polymer with a polyester backbone, with fluorinated substituents as pendant side groups) or a fluorinated acrylic copolymer (similar to many of the acrylic copolymers currently used in styling products - just with a fluorine twist, if you will). Whatever the specific case may be (and as a polymer scientist, I am so hopeful that one day we can know the actual structure), it is most certain that this polymer has a significantly lower molecular weight than PTFE and most silicones used in hair care products. The marketing material of Living Proof states that these smaller molecules do not weigh down the hair, and that for this reason the consumer can use much more of the product and coat all of the hairs on her head entirely. This creates a very flat, sealed cuticle layer and forms a true protective shield against the ravages of humidity upon the hair.

PolyfluoroEster is both hydrophobic and lipophobic, meaning it is neither water soluble nor oil soluble. Different ingredients in the formulation work to help emulsify the polymer and actually get it into solution in their product. These polymers not only repel water, but also repel oils and dirt (particulate matter) from the environment, so it becomes possible to go longer between shampoos, which helps to minimize the inevitable damage that occurs with shampooing. That is a great feature, especially for those of us always in pursuit of that elusive creature, beautiful second-day hair.

Fluoropolymers have extremely low surface energy, which allows the polymer to spread very evenly and to form a very smooth, thin film on the surface of the hair (referred to in their product literature as a microfilm shield). This low surface energy and smooth film formation helps to increase slip and decrease friction between adjacent hair strands. This prevents tangling and eases combing, which can be very beneficial to the health of hair. It also acts as another mechanism for frizz prevention, because it helps prevent static charge accumulation that can occur from friction between hair strands.

This polymer is reported to have a low refractive index, which is credited with giving it the ability to impart high gloss and shine. I have to admit to being perplexed by that, because silicones have a high refractive index, which is responsible for their ability to be such fantastic glossifiers. I intend to review my understanding in that area a bit and also to contact Living Proof directly, as I have a few more questions for them anyway. I will be happy to report back anything they share with me.

Is this PolyfluoroEster compatible with curly hair?

These products definitely look promising for curly-haired consumers who suffer from problems with frizz, especially in humid climates. It seems as if the product line is very gentle, with their sulfate-free shampoo and their moisturizer-rich conditioners. Their styling products look very reasonable as well. The polymer is most definitely not water soluble, so one might have concerns regarding a shampoo-free (CG) routine. However, it is my hypothesis that due to its molecular structure, this polymer does not build up on itself, similar to amodimethicone, so many who get good results from amodimethicone-containing products might be very successful with this as well (perhaps even moreso). Much like amodimethicone though, I am curious does thoroughly remove it from one’s hair, as it wouldn’t seem to be susceptible to most usual surfactants. I am hoping to get more information on this from the scientists at Living Proof.

Most of the reviews I have seen for the product have been really good, so I feel that the NoFrizz line of products is very promising. Apparently, performance of this product improves with repeat applications too, so make sure you use it for a few days or longer when evaluating it on your hair. I have heard that at least one of the styling products can be quite stiff for those of us with curly hair, and that can make the hair feel brittle and dry, so be careful which product you choose and perhaps layer it with their leave-in conditioner.

The main downside of these products is their cost. However, the polymer itself is in the products at higher concentration than other polymers usually are, and it is probably quite expensive to make right now. Also, a huge amount of money has gone into the acquisition of the absolute crème de la crème of the brains in the scientific and beauty industry and into the building of state of the art laboratories. All of that comes with a price! I am hoping to try some soon myself. (Dear Santa…)

I am really interested in these products and in this innovative new company, so I would love to get e-mails or comments below from you guys about how you feel about it after trying it.

Addendum

I had the most wonderful opportunity to speak to Jessie Vallette, a customer service representative at Living Proof, after I had completed this article. I was so pleased with the level of knowledge she had and her willingness to discuss my questions in detail. Again, my hat is off to this company. So, on to the information she shared.

Polyfluoroester is definitely completely hydrophobic, and so is not water insoluble. However, when the hair is immersed in water, some small quantities of it will come off of the hair. Immersion in water will also still cause the hair to swell and the cuticle to open, so it is still possible to clean the hair and for conditioner to do its job. They have found that their own very gentle shampoo does remove the polymer from the surface of the hair, so it is not necessary to use a sulfate-containing cleanser.

Also, she confirmed that polyfluoroester does not build up on itself once it has adsorbed onto the surface of the hair, so it seems to behave in a very similar manner as amodimethicone in that respect. Many curly-haired consumers who use a no-shampoo or low-shampoo regimen have been successful with products that contain amodimethicone for this reason. According to Jessie, this polymer should be even easier to work with, so the No Frizz line may well outperform products that contain amodimethicone when it comes to frizz-fighting.

Tonya McKay

Most of us with curly hair are pretty well-versed now in the need for our hair to be very well hydrated and conditioned. But what exactly does this mean? There are so many products on the market that claim to be the solution for our dry, frizzy tresses, but which do we really need? Plentiful also are the words used by marketers and hair care experts when telling us what we need for our hair to be healthy and beautiful. Among these are humectant, moisturizer, emollient, detangler, reconstruct/repair, and color protecting. What do these terms really mean, and what ingredients should we be looking for if we desire some of these properties?

There are numerous types of conditioners available in the marketplace, so we will examine some of the more common categories. My hope is to aid the consumer in understanding what the proposed benefit of a particular type of conditioner is and also what ingredients can be expected to help achieve the desired outcome.

Types of Conditioners:

Moisturizing

Moisturizing conditioners are ones that help retain and/or add moisture, i.e. water, to hair. These types of conditioners rely heavily upon the properties of ingredients such as humectants, fatty alcohols, light oils such as aloe or jojoba, and frequently vitamins such as panthenol (which also act as humectants). Oils or polymers that form an occlusive film on the surface of the hair are also often found in these products, as they aid in moisture retention in the interior of the hair shaft.

Some ingredients you might see in a moisturizing conditioner:

• glycerol
• propylene glycol
• panthenol
• erithritol
• sodium PCA
• hyaluronic acid
• sorbitol
• fructose
• fatty alcohols
• polyquaternium polymers
• cationic surfactants (cetrimonium chloride, dicetyldimonium chloride)

Deep Conditioners

Deep conditioners, repairing conditioners, and reconstructors all generally have a few properties in common. They contain significant amounts of proteins, hydrolyzed proteins, and amino acids, which can penetrate through the cuticle and absorb into the hair where they can add strength to the existing complex protein-based composite inside the hair shaft. These ingredients can also adhere to the surface of the hair and act as patches over areas that have been depleted of protein.

Well-formulated deep conditioners also contain oils, esters, or fatty acids, called emollients. These ingredients help to soften the hair and add elasticity to it. This is especially important when proteins are being used, as they can make hair very hard and brittle.

Hot oil treatments contain only or mostly oils, which penetrate into the hair after topical application by placing the client under heat. Some people enjoy the result they get from treatments such as these. However, the use of heat on hair should always be undertaken with caution, in my opinion.

Key ingredients in deep conditioning products:

• Proteins
• Hydrolyzed proteins
• Amino acids
• Plant oils
• Mineral oil
• Silicones (dimethicone and derivatives)
• Esters (glyceryl stearate, isopropyl palmitate)
• Fatty acids (coconut fatty acid, stearic acid, lauric acid)

Acidifying

Acidifying conditioners have a pH in the range of 3.0 - 4.0, rendering them slightly more acidic than most other conditioners (which are typically formulated to have a pH in the range of 4.0-5.0). These types of conditioners have a few benefits. Acidifying rinses or conditioners lower the pH of hair to or slightly below its isoelectric point (estimated to be at a pH between 3.0-3.7), which is its ideal state. At the isoelectric point the cuticle is tightly sealed, the keratin proteins possess no residual electrostatic charge, and the hair shaft is thought to be harder and in the state most protected from the environment.

Some ingredients used in acidifying conditioners:

• Behentrimonium chloride
• Stearalkonium chloride
• Amine oxides
• Cetrimonium chloride
• Citric acid
• Ascorbates
• Citrus extracts

Detanglers and Leave-in Conditioners

These types of conditioners are generally lighter than moisturizing and deep conditioners and contain a greater amount of water in the formula than do other products. Heavy oils and proteins are not typically part of these conditioners, but instead they rely upon lighter ingredients.

Detanglers and leave-in conditioners work by depositing small amounts of materials on the surface of the hair that act in a variety of ways to minimize friction when combing. Humectants are often used in these formulations for their moisture attraction and retention properties. Other ingredients are selected because they neutralize residual negative charge at the surface of the hair (cationic polymers, cationic surfactants). Some of the ingredients are included because they form a smooth film on the surface that provides lubrication and eases the force required for combing through the wet hair (dimethicone, amodimethicone, fatty alcohols). Silicones have an added benefit of leaving a smooth, highly reflective film on the surface of the hair, which imparts a high amount of gloss and shine.

Typical ingredients found in detanglers and leave-in conditioner:

• Amodimethicone
• Cyclomethicone
• Propylene glycol
• Panthenol
• Botanical extracts
• Glycerin
• Glucose/sucrose
• Panthenol
• Cetrimonium chloride
• Polyquaternium-11
• Fatty alcohols

Color Protecting

Color protection conditioners typically will contain moisturizing agents, protein (or derivatives thereof) for filling in gaps left by damage from the coloring process, oils or fatty alcohols, and compounds that act as UV absorbers. Both UVA and UVB radiation can cause damage to hair and loss of color, so many products will try to include ingredients that can absorb in both regions. UVA protection is critical for those with chemically colored hair, especially red hues, as it is most susceptible to these rays.

UV absorbing ingredients found in hair care products:

• Ethylhexyl methoxycinnamate
• Benzophenone
• Polymers, such as Polyamide-2
• Salicylates
• PABA
• Dimethylparamidopropyl laurdimonium tosylate

Thermal Protection

Some conditioners are designed to protect hair from heat damage that can occur when blow drying or styling with flat irons and curling irons. These products almost always rely upon the thermal insulating properties of silicone polymers.

Ingredients that protect from thermal damage:

• Dimethicone
• Dimethiconol
• Amodimethicone
• Cyclomethicone

Many conditioners will combine different categories of ingredients, in order to have multiple attributes. Many leave-in conditioners will have sunscreen additives in them. Color protection conditioners may also contain silicones meant to impart gloss and also provide added protection against heat damage. Daily conditioners may include proteins or protein derivatives in order to combat day-to-day damage. So, when choosing a product, really look at the label and determine what the major components are and what you can expect the primary function of that product to be.

The role of conditioning agents, emollients, moisturizers, humectants, and proteins are to fill in the gaps where structural damage has occurred to the surface and interior of the hair, to bring moisture into the hair or to increase moisture retention, to impart suppleness and elasticity, and to provide lubrication along the hair shaft. All of these functions help to minimize mechanical and environmental damage that occurs through daily combing, styling, washing, and exposure to the elements. Thus, conditioners are powerful and essential products that make the hair more attractive, softer and more manageable, and less likely to incur new damage. As the hair is protected by daily use, new hair can grow in and remain healthy and strong, so while conditioners may not be able to truly repair and reconstruct a damaged hair strand, they do indeed provide much benefit.

Tonya McKay

Butters, oils, and waxes all come from fats that are derived from plants or animals, and have two basic components; fatty acids and alcohols. The difference between butters and oils is primarily whether or not they are solid at room and/or body temperature. Although they are both composed of groups of fatty acids, there are differences in the molecular composition and structure of butters and oils that are responsible for these differences in melting points.

Factors that determine melting point of lipids

• Molecular weight - lower-molecular-weight fatty acids have a lower melting point, so that they are liquid at room temperature or body temperature. Higher-molecular-weight fatty acids form crystalline structures that persist to higher melting points, and so they are usually solids at room temperature and higher.
• Saturated molecular structure — longer-chain fatty acids without any double bonds are straight chain molecules (like long snakes) that are able to closely pack next to one another This close-packing induces crystallization, which requires more energy to break apart than molecules not packed together into a crystalline or semi-crystalline structure. For this reason, the melting points of these types of fatty acids are much higher. This means the “oil” will exist in a solid state at room temperature or even body temperature.
• Unsaturated molecular structure — unsaturated molecules have at least one double bond somewhere in their structure. This creates a kink or branching effect in the geometry of the molecule. This prevents unsaturated fatty acids from getting too close to one another, thereby preventing crystallization. These molecules have lots of space between themselves, which allows for more mobility of the molecules and results in a lower melting temperature. These oils may be liquid at room temperature or melt upon contact with skin.
• Stearic acid, a saturated hydrocarbon molecule with 18 carbons (relatively long-chain fatty acid) has a melting point of 69.6°C (157.28°F). Oleic acid, a monounsaturated hydrocarbon molecule, has a double bond in it that creates a kink in its geometry, which makes it more difficult for adjacent molecules to pack tightly next to one another. It has a melting point of 10.5°C (50.9°F). Polyunsaturated acids, such as linoleic and linolenic, have multiple kinks in their chains and are liquid at very low temperatures (melt point = -5°C (23°F) for linoleic acid).
• Linolenic acid, polyunsaturated fatty acid.
• Linoleic acid, polyunsaturated, omega-6 fatty acid.
• Oleic acid, monounsaturated fatty acid.
• Stearic acid, saturated fatty acid.

Clearing up some misconceptions

various oils

Coconut butter, avocado, almond butter and peanut butter are not actually butters, in terms of the nomenclature we are discussing. In these products, the flesh of the nut or fruit is pressed and included with the oil, which provides the food source with proteins and water, as well as fatty acids. This is not a butter in the technical sense THEN WHAT IS IT? WHAT IS THE DEFINITION OF BUTTER?, but this is a common usage in food products. Another point to keep in mind is that in some cases, the unsaturated fatty acids in the oils of these fruits and nuts are hydrogenated to create a more solid texture. This can change the properties of the product significantly.

Another bit of confusion on this topic of oils, butters, and waxes is due to misleading terminology in the nomenclature system. It is not uncommon to read assertions that emulsifying is waxy or oily and prone to build-up. In fact, emulsifying wax is not a wax at all, nor is it an oil. It is a group of ingredients (derived from fatty acids ) used as a nonionic surfactant mixture that is highly effective at facilitating mixing of oils and waxes into aqueous solutions. Specifically, it is most often these ingredients: Cetearyl Alcohol, Polysorbate 60, PEG-150 Stearate & Steareth-20. All of those components are water soluble, with the exception of the fatty alcohol. It is possible that people who dislike products containing this ingredient are actually sensitive to the oil or butter being emulsified by emulsifying wax, or they are sensitive to buildup of fatty alcohols (cetearyl alcohol) on their hair.

Fatty acid composition of common vegetable butters and oils

Depending upon where it is grown and the environmental conditions of that year, as well as soil quality, shea butter can vary significantly in its ratio of stearic acid to oleic acid. This will affect its melting point, and thus, its softness. If there is a lot more oleic acid relative to stearic acid in a particular batch, it will be a much softer and oily product, and will behave somewhat differently on the hair. Processing (methods of extraction, filtering, use of heat, hydrogenation) can also drastically affect the unsaturated oil composition, so if purchasing shea butter itself, carefully read the label so you are aware of the quality of butter you are getting. A pure shea butter contains no emulsifiers or perfumes, but is purely the mixture of fatty acids that were extracted from the fruit.

shea butter

Incorporation of shea butter into a conditioning product involves melting it and dissolving it into an emulsifier and then mixing that into the product. Although the butter is melted and mixed into a liquid, its mixture of fatty acids should remain intact (unless high heat was used, which is not typical). Therefore, it is still the same “butter”, simply because the term butter is not actually very meaningful. The inherent molecular structure is unchanged.

It is also interesting to note that while coconut oil is comprised almost entirely of saturated fatty acids, it is still referred to as an oil, rather than a butter. This is due to the lower molecular weight of the major fatty acids in coconut oil, which give it a lower melting point; typically right around room temperature. This is another clue that the terms butter and oil are not always very precise or meaningful. For this reason, it is a good idea to look at the fatty acid content of a particular butter or oil you would like to try and to understand what sort of performance you might expect based upon its chemistry, rather than what it is called.

Which is best for our hair?

So, we have established that all of these butters and oils are made up of different mixtures fatty acid molecules. What specifically accounts for the varying preferences expressed by consumers? Some curly-haired people extol the virtues of butters, while others adamantly proclaim oils as their holy grail ingredient.

The major components of butters and coconut oil are one or more saturated fatty acids, while the major components of most oils are a mixture of mono- and polyunsaturated fatty acids. One must assume that the differences in performance when used as emollients for the hair are a direct result of these differences in molecular structure. This is exactly the reason, and the science is fairly straight forward.

You will recall recent discussions we have had regarding the nature of the cuticle layer of the hair. Pores in the cuticle layer (whether from damage or from its being slightly open due to being wet) allow passage of some molecules into the cell membrane complex layer that is just beneath the cuticle scales. The fatty acids in this lipid layer act as a diffusion port that allows some fatty acids to penetrate the hair shaft. However, due to molecular structure and geometry, not all fatty acids are created equal in their ability to diffuse into the hair.

murumuru butter

Generally, molecules with a straight chain geometry (saturated fatty acids), such as stearic acid, lauric acid, and palmitic acid can easily fit through the pores of the cuticle layer and slither through the CMC and into the interior of the cortex. Recent spectroscopic studies have allowed scientists to confirm that monounsaturated fatty acids are also able to readily penetrate the interior of the hair via this route. However, polyunsaturated fatty acids seem unable to penetrate into the interior of the hair at all, and remain either adsorbed onto the exterior surface of the hair or may get wedged into the cuticle layer.

Fatty acids in the interior of the hair can provide brittle hair with much-needed suppleness and elasticity. However, porosity is a very important factor to consider when using easily absorbed oils and butters. If one has very porous hair, it can absorb excessive quantities of these oils, which can lead to a host of problems. Among these could be greasy feel, dull appearance, limp hair, a swollen and open cuticle, frizz, and tangling. It can be very difficult to remove excess absorbed oils, in my experience, requiring the use of harsh surfactants, which strip the hair of its own lipids.

Oils high in polyunsaturated fatty acids may provide ease of wet combing and prevent static build up and fly-away hair. In addition, they form a barrier film on the surface of the hair, preventing moisture from escaping the interior of the hair. However, they might contribute to hair that feels greasy or sticky to the touch. Oils on the surface of the hair can also attract dirt to your hair. Another potential concern is that if these types of oils are indeed wedged into the cuticle layer at all, hair becomes vulnerable to the dangers of having a raised or rough cuticle.

My recommendation is to try small quantities of different oils and butters and carefully observe your results and preferences. Then, when you find things you really like or dislike, look into the fatty acid composition of the things you tried. This will help you determine if your hair needs saturated, monounsaturated, or polyunsaturated fatty acids, and you can then choose your products accordingly, armed with your knowledge of the underlying chemistry!

Tonya McKay

Porosity is the term used in the science of hair care to describe how easily water and other matter can diffuse back and forth through the cuticle layer and into or out of the cortex. Hair is much like a sponge, capable of absorbing water and other substances from the environment, and also susceptible to losing precious moisture and lipids to the environment. Maintaining an optimal balance of moisture in your hair preserves its suppleness, strength, and shine. This is especially important for those of us with curly hair, as it greatly influences the health and beauty of our tresses.

Porosity Classifications

The individual scales of the cuticle overlap one another like the feathers of a bird or scales on a fish. This amazing system of flexible and responsive scales allows diffusion of oils and moisture into and out of the hair as needed. Porosity is determined by how tightly the cuticle scales adhere to the surface of the hair shaft and also by how thoroughly adjacent scales overlap one another.

Low Porosity: Hair described as having low porosity is characterized by a very tightly bound cuticle layer, where the individual cuticle scales lie flat and overlap one another. Low porosity hair is often quite shiny, especially if it is a darker color. Overall this type of hair is considered to be quite healthy. If your hair repels water when you attempt to wet it, that is a good indication that it has low porosity. It can be quite difficult to process, because it resists penetration of the chemicals being used.

Low porosity hair is more prone to an excessive accumulation of protein if deep conditioning products are used and will feel very stiff and straw-like. It requires products rich in moisture and emollients and also benefits most from products that contain humectants, which attract moisture to the hair and hold it there. If hair with very few or very small openings becomes dry for some reason, it can be more difficult to restore proper moisture balance to it. In this case, a deep conditioning treatment with moderate heat would be a good way to ensure the cuticle is sufficiently opened up to allow moisture to enter into the cortex.

Normal Porosity: Hair possessing average porosity will generally require the least amount of maintenance. It allows moisture to pass into the cortex as needed, but resists permitting too much water to penetrate. Repeated works by various research groups have found that healthy hair of average porosity can absorb water up to a maximum of 31.1% by weight. Normal porosity hair has a tendency to hold styles well. Perming or coloring can be done in a predictable manner, following the usual guidelines of the product. However, one must note that these processes will damage the hair and increase its porosity over time. An occasional deep conditioning treatment with a protein-containing product will be of benefit, but proteins should not be included in the daily regimen.

Opened highly porous cuticle

High Porosity: High porosity is an unfortunate result of damage to the hair. Chemical processes, harsh treatment, and environmental exposure are all responsible for causing cumulative, irreversible damage to the cuticle layer. This damage creates gaps and holes in the surface of the hair shaft—essentially chinks in its armor. Hair with this type of uneven, pitted and rough surface is prone to damage from more and more sources, resulting in a cascade of effects that culminate in unmanageable and unlovely locks.

Hair with a great deal of porosity has been found to be capable of absorbing significantly higher amounts of water than hair or normal or low porosity (up to 55%, in contrast with 31.1% for healthy hair). Excessive absorption of water from the atmosphere causes frizz and tangling on humid days. Total immersion of high porosity hair during bathing, swimming, or shampooing can lead to significant breakage due to loss of elasticity from the sheer weight of the water absorbed. It also takes on color much more quickly and in higher concentrations than normal porosity hair when undergoing a chemical color process.

People with high porosity hair should use products with lots of moisturizers and emollients and also use anti-humectants in high heat and humidity climates in order to seal their cuticle against excessive absorption of moisture from the air. Protein treatments can also be very helpful for patching some of the holes in the hair, but one must follow up with moisturizing products in order to avoid a stiff texture. Rinsing with a slightly acidic rinse will help flatten and seal the cuticle. Some clear color applications have proteins in them than can patch the gaps in your hair also. Consult your professional hair stylist for more information about such products.

Genetic or Biological Contributors to Porosity

Genetics and hair type (straight, wavy, or curly) contribute to how tightly the cuticle layer adheres. Some people have a circular hair shaft, which is optimal for cuticle scales to lie flat and overlap one another, resulting in low porosity. Other types of hair are more elliptical or even flat and ribbon-like. This geometry doesn’t allow for all of the cuticle scales to lie flat and overlap one another along the axis of the hair, especially at the outer edges of the hair strand. This creates areas of discontinuity in the cuticle layer, which adds porosity to the hair.

In a similar fashion, curly hair has a tendency to be naturally higher in porosity than straight hair. This is because the spirals in the helical configuration of the curls create areas where individual cuticle scales are raised slightly away from the longitudinal axis of the hair. The curlier the hair is, the more breaks you have in the smoothness of the surface, so the porosity is invariably increased.

External Contributors to Porosity

Damaged cuticle

Environment: Exposure to UV rays for prolonged periods can fuse cuticle scales together, which inevitably leads to further damage of the cuticle layer. It is a good idea to cover your hair when in the sun or use products which contain sunscreen agents.

Chemical Processing: Perms, relaxers, and coloring processes all require the cuticle to first be opened via application of an alkaline solution. This allows the chemicals to access the interior of the hair shaft in order to make permanent changes to the structure of the proteins that are the building blocks of the hair. All of these processes are capable of doing permanent damage to the cuticle layer. This damage builds up with repeat use of the chemical process. Bleaching is the most damaging process, followed by perming and relaxing, with most permanent coloring processes being the mildest.

Heat treatments: Heat from a blow dryer, flat iron, curling iron, or hot curlers can all cause irreparable damage both to the cuticle and the cortex of the hair. These tools can heat water inside the hair past the boiling point and cause the hair to rupture from the inside out. It is not difficult to see how this could increase porosity.

Mechanical Damage: Combing, brushing and friction from scarves, and hats, and scrunchies all cause damage to the cuticle layer. Over time all of these can result in torn and ripped cuticles, thereby increasing the porosity of the hair. Curly hair should only be combed with a wide-tooth comb while it is wet and coated with a conditioner for maximum slip. This minimizes friction and subsequent damage to the scales.

Shampooing with sulfates and soaps: In previous articles, we have discussed that the cuticle layer is comprised not only of keratinous scales, but also a layer of fatty acids on the top surface that protect the hair from moisture, as well as a layer beneath the scales called the cell membrane complex (CMC). The CMC acts as cushion and as a cement the keep the cuticle scales firmly attached to the hair. A large portion of this CMC is made up of a lipid layer of mixed fatty acids, including 18-methyleicosanioc acid (18-MEA), stearic acid, and palmitic acid.

At normal formulation levels (15-20%), harsh surfactants in shampoos, such as SLS, SLES, ALS, and ALES, are capable of dissolving the lipid layer in the CMC and removing the 18-MEA from the surface of the cuticle. This creates irreparable gaps in the cuticle layer, increasing porosity of the hair. Also, by dissolving the protective fatty acid layer from the surface of the cuticle, the hair is rendered more hydrophilic (water-loving), which is a very dangerous state for hair as it becomes more susceptible to frizz, tangling, and damage to the cuticle scales. This information merely confirms what we have been told about the hazards of using these types of surfactants on our hair.

Another very important ingredient to avoid for long, curly hair especially is soaps. In the past, I have written an article cautioning users of soap to be careful, but basically concluding that it was probably okay to use soaps with an acidic rinse and lots of moisturizing agents. Based on the following information obtained from the research of Dr. Ali Syed (a hair care researcher who specializes in African and curly hair), I cannot in good conscience advocate use of any soap products on curly hair.

Soap molecules are salts of fatty acids found in plants and animal fats. They are somewhat alkaline and cause the hair to swell and the cuticle to raise up away from the surface of the hair shaft. These molecules are then able to penetrate through the cuticle and into the CMC where they neutralize the fatty acids in the lipid layer, rendering them water soluble. The fatty acids are then rinsed away in the shower and are gone forever. Use of soap to cleanse one’s hair, especially long curly hair, seems to be a really effective way of permanently destroying the cuticle layer and making the hair very highly porous. This is an example of why natural may not always be superior. It is no surprise that researchers have invested years and many millions (billions) of dollars to develop more gentle cleansers for our hair.

Porosity and Tensile Strength

Increasing porosity of hair has been found to correlate with decreasing tensile strength of the hair. What this means is that as the porosity goes up, it becomes much easier to break the hair. Gaps and flaws in the surface, which allow the hair to absorb much higher quantities of moisture, create stress concentration sites and weakness throughout the strand that cause the hairs to break easily.

What to do? Prevention is the best medicine when it comes to porosity problems.

• Use the right products for your hair.
• Avoid harsh surfactants and soaps.
• Only comb tangles with a wide-toothed comb when hair is wet and saturated with conditioner.
• Avoid chemical processes as much as possible.
• Avoid thermal styling tools.
• Protect your hair from the sun and the elements.
• Get regular trims.
• Treat your hair as gently as you would an expensive cashmere sweater!

If you already have a problem with high porosity, please make sure you have an excellent deep conditioning treatment available, preferably one that contains proteins. Use lots of conditioning and moisturizing products, especially those containing natural, plant-based oils. Avoid all of the sulfate-based surfactants and soap bars. Use a mildly acidic rinse regularly and avoid humectants. If possible, avoid the processes that created the high porosity, and get your hair trimmed regularly. These things should help restore your hair to a more manageable porosity level, but it will take time.

Protect your cuticle!

Tonya McKay

Recently, I asked for input from some of our readers for topic ideas. The response was wonderful! I never fail to be impressed by the depth of thought you ladies and gentlemen are putting into your selection and usage of hair care products. Many thought-provoking questions and ideas were presented, and I find myself being consistently challenged and sent down interesting scientific avenues. I will be working many of your questions into articles or Q&A format over the next few months and welcome more ideas and questions at any time.

Through the years, I have sensed perhaps a growing frustration amongst the ever-increasingly-informed curly populace. This frustration seems to be rooted in the fact that no matter how much you learn about ingredients, water hardness, pH, water solubility, dew point, etc., there is no one good formula or answer to help you consistently have those perfect, soft and shiny curls that we all so desperately desire. There are reasons for this.

The understanding of the health and behavior of hair is an extraordinarily complicated area of study that involves many different many aspects of scientific study. The topics are highly complex and interdisciplinary and are studied individually in fields such as biochemistry, microbiology, colloid and surface chemistry, water chemistry, polymer chemistry and physics, thermodynamics, meteorology, and even cosmetology. A scientist or practitioner must usually devote many years of their life to just one of these areas to become an expert in it. It is necessary when working in a field related to hair or skin science to delve into other fields and to develop interdisciplinary skills, but generally each of us relies upon our peers in other fields to help us in the areas in which we are not as strong.

In my experience in the field, large companies who spend millions on the research and development of hair and skin care products every year have many facets to their programs. Typically, there are development labs where chemists work on making new products. Those chemists work with suppliers from companies who make and provide raw materials, and they consult with the supplier’s chemists and biochemists, who are the resident experts in the individual ingredients. There are microbiology labs, where the growth of organisms are studied and preservatives are tested and refined. There are analytical labs filled with scientists who are experts in testing and understanding the chemical and physical properties of materials, who do testing on hair and skin to see how they are influenced by products and processes. There are groups of engineers who collaborate with the laboratory chemists in pilot plants to scale up development of a product into a manufacturing process. There are quality assurance laboratories, where exhaustive testing is performed on finished products and data is tracked statistically in order to catch products that deviate from the accepted standards. There are also typically experimental hair salons, where volunteers come in and have their hair done and “test” new products and provide feedback on results. (To my knowledge, none of them employ meteorologists!)

My point is that the personal care product industry is a multi-billion dollar one that employs many scientists all around the world for good reason. There just isn’t one definitive answer for all of our hair questions and needs. There are too many variables and too many different perceptions of how “good” hair looks and feels. So don’t be discouraged if this stuff seems complex, elusive, contradictory, and nonsensical to you at times. Just keep reading up on it, trying different things, and then when you find something that works, stick with it! (until it stops working again, which we all know will happen eventually…)

To kick off, let’s address this query from a reader: “We have learned a lot recently about dew point and how it can contribute to the behavior of our hair. Does air temperature play any role? For instance, the dew point could be 40 on a very cold day, and it could also be 40 on a very hot day. Most people have noted that they would not use the same combination of products for those two scenarios, despite the dew point being the same. What accounts for that?”

First of all, allow me to give all of NaturallyCurly’s readers kudos for having such a variety of products in your arsenal, combined with sufficient daily presence of mind that you can have different routines depending up on the weather! I desperately need some of you to take me in hand help me out with my own products and routine.

Now, to the question!

The short answer is yes, your hair will behave differently depending upon the temperature to which it is exposed, even if the dew point remains constant. The reason for this is that all materials exhibit a behavior known as thermal expansion, which occurs when they absorb heat energy and experience a subsequent change in volume. This can be a rather complicated process for hair, as it is a biological composite comprised of many different parts.

Last month, we went into some detail describing the complicated composition of our hair (Structure of human hair). You may recall that each human hair is made up of an outer layer of many scales called the cuticle, layers of fatty acids and lipids, and an inner core called the cortex, which is a complicated structure itself. The keratin molecules present in both the cuticle and the cortex, water molecules, and lipids which make up this fascinating biopolymeric composite are all susceptible to expansion and conformational changes due to variations in temperature. Water molecules exist in several different states within a hair strand - as free water, water loosely bound to keratin fibers, and water tightly bound to keratin fibers. Of all of the components of hair, water is probably the most influenced by fluctuations in temperature in the range we typically encounter in the environment.

When hair is exposed to higher temperatures, cuticle scales swell and lift away from the surface of the hair. This creates a much more porous hair strand and also an uneven surface, much more prone to tangling and breakage. Simultaneously, both free water molecules and those loosely bound to keratin molecules in the cortex get excited and begin to expand, causing swelling inside the hair cortex. Eventually, water molecules can begin to diffuse out of the cortex and evaporate out of the hair shaft through the gaps in the cuticle layer.

As water leaves the interior of the hair, the α-helix structure of the keratin protein becomes disturbed which disrupts the crystalline order within microfibrillar structures in the interior of the cortex. In a hot, dry environment, this can mean hair becomes very parched and frizzy. This also means a loss of elasticity, so the hair is more fragile and prone to breakage due to mechanical damage from combing or handling.

In a hot and humid environment, this swelling of the hair opens up the cuticle and allows water from the environment to penetrate the hair shaft, which further increases the swelling of the cuticle and hair shaft. Have you ever walked into a hot environment from a cold one and just felt your hair lift off your head, or started working out in the gym and felt your hair expanding and getting beautifully frizzy as your body temperature went up, or had the frizz set in when you were cooking in the kitchen? All of these phenomena are related to the expansion of hair (and the water within it) due to exposure to heat.

Anyway, to answer your question directly — yes, the temperature is very important. The dew point may give you one piece of information, but the temperature is also extremely relevant. When it comes to hair, especially curly hair, internal moisture, atmospheric moisture and environmental temperature are all very important and interrelated. In my own experience, my hair adores colder weather, and I don’t have to put much thought into my routine in lower temperatures, so I put most of my energies into keeping my hair super-moisturized and protected in hotter climates. For me, this means lots of good conditioning product left in my hair after rinsing and the application of a good gel product that helps seal the cuticle and keep it as flat as possible. So far, nothing I have tried is perfect though, especially in Florida heat and humidity!

Tonya McKay

As a polymer scientist with a love for biological structures, I find hair and skin to be extremely fascinating systems. Human hair is an intricate composite structure comprised of keratin proteins, lipids, polysaccharides, water and pigment particles. All of the individual components are complex and perform very specific functions. Those of us with curly hair are concerned a lot about our hair’s texture and porosity (a popular buzz word of late). These two factors are primarily based upon the structure of the cuticle — the outer layer of our hair.

Fig. 1: Undamaged hair

The scanning electron microscope image in Figure 1 shows highly magnified detail of the exterior surface of a strand of human hair. The external layer is called the cuticle, and is much like bark on a tree. Both the cuticle layer and tree bark are made up of many smaller, individual pieces (called scales when referring to the cuticle) that work together as one overall unit to perform a function. The job of the cuticle is to provide protection to the hair shaft from mechanical and thermal damage, while allowing moisture in and out as needed. The cuticle structure is an amazing work of nature, because it is strong, yet flexible, and is made up of many pieces, which allows it to act as a seal to protect the inner cortex of the hair, and yet also allows it to be permeable, or porous.

The center of the hair shaft is referred to as the cortex, and is a very complicated structure filled with many different substructures and clusters of structures made of keratin protein, lipids, and other matter. Water provides the means for the necessary hydrogen bonding between the keratin fibers to occur that is essential for the maintenance of hair strength, elasticity and integrity. Without moisture in the cortex, the hair becomes thin, frizzy, and much more prone to permanent damage and breakage. Thus, the cuticle layer performs a very important duty by protecting this delicate interior of the hair and helping it maintain the proper balance of moisture.

Structure of the Cuticle

The cuticle itself is a multi-laminate structure, like stacked sheets of paper, composed of fatty acids, proteins, and other cellular matter. Below is a description of each layer.

• Epicuticle — This surface layer of the cuticle is made up of lipids and proteins and is also found on the bottom of the stacks of layers.
• A-Layer — This layer is comprised of proteins very high (35%) in cystine, which enables the layer to be highly crosslinked. This layer gives toughness to the hair and also provides physical protection from heat and other potential threats.
• Exocuticle — This layer has approximately 15% cystine, so it is less strong and tough than the A-Layer, but provides similar protection.
• Endocuticle — This layer contains only 3% cystine, and so is only very lightly crosslinked. This means that this layer is the only cuticle layer to swell in the presence of water. This causes the entire cuticle to swell and lift away from the hair shaft, resulting in a ruffled cuticle that allows the passage of material both into and out of the hair.
• Cuticular Cell membrane Complex (CMC) — This layer is made up of polysaccharides and several lipids (fatty acids). This layer acts as the glue that holds the cuticle together and holds it to the hair shaft.

Cuticle Damage

Fig. 2: Chemically altered hair

A perfectly healthy hair that has not been exposed to harsh chemical processing, prolonged sunlight, or rough thermal and mechanical treatments (often called “virgin hair”) will have a cuticle layer such as the one shown in Figure 1. The individual keratin scales lie very flat, have fairly smooth edges, and overlap one another, forming a flat, tight sheath around the interior of the hair shaft. A hair in this condition is highly protected from the environment, retains the most moisture, and generally is more reflective, giving the hair shine and gloss. (This latter feature is variable, depending upon the color and the degree of curl of the hair).

Unfortunately, most of us don’t have hair protected by such a beautiful, intact cuticle. As hair ages, it is continually exposed to sunlight, water, pollution and external mechanical forces. UV radiation from sunlight can break down some of the keratin bonds and cause deterioration of scales and cause them to lose some of their structural integrity. Mechanical forces such as combing, bruising, curling, pinning up or binding the hair can all catch the edges of cuticle scales and ruffle or raise them, creating a rough surface more prone to tangling and tearing. Rough treatment can even pull cuticles off entirely.

Water causes the endocuticle layer to swell, which lifts the entire cuticle and creates a rough surface. This leaves hair more delicate and susceptible to tangling and damage from friction between adjacent hair strands or from mechanical forces. For this reason, wet hair should be treated very gently and conditioners must be used to reduce friction and combing forces. Hair exposed to high humidity should be protected by extra conditioning and anti-humectant products in order to avoid this effect, which can lead to very damaged summer hair. (Read an article about summer hair here.)

Fig. 3: Damaged cuticle

These (scary) images show strands that have had extensive damage done to the cuticle layer from chemical processes (coloring, perming, relaxing). It is evident from viewing these images that once the cuticle layer is damaged, the cortex becomes exposed and the entire hair is extremely vulnerable to virtually any threat. The best solution in these extreme cases is to have a professional stylist trim the hair.

Curly hair is more susceptible to cuticle damage due to its structure and due to its lower amount of internal moisture. As a curly hair strand bends and curls around itself, sections of the cuticle layer can become slightly raised. These individual scales can cause tangles and breakage, get caught on a comb or scrunchie and magnify the effects of other types of damage that can occur to hair in our daily lives. For this reason it is imperative that people with curly hair avoid as many damaging conditions as possible, moisturize as much as their hair will tolerate, and use products that smooth the surface of the hair. It is critical to remember that prevention of damage is always the goal. Once cuticles are damaged or removed, further damage is inevitable until that portion of the hair is removed.

Next month I will discuss how the cuticle layer and our treatment of it affects porosity and what that means for our hair.

Tonya McKay

I don’t usually talk much about my hair, but lately it has been dry and tangled! Seriously — it is awful. I think a poor choice in a do-it-yourself color process and my being in-between “holy grail” conditioners are both to blame. Since I hate the feel of a haystack on my head, I have been experimenting with different oils and home treatments, while I ponder which commercial products to purchase for a (hopefully) more long-term solution.

While perusing the forums here at NaturallyCurly.com in hopes of discovering a new conditioner, I have read several discussions about avocado and wheat germ oils and whether or not they contain significant amounts of plant protein. Since some of us with curly hair love and seek out conditioning products that contain proteins, while others avoid them like the plague, it is an important question. Thus, I thought it would be relevant and possibly fun to examine these two plant oils more closely.

Avocado oil and wheat germ oil are derived from their respective sources using various methods; typically solvent extraction, cold press or mechanical extraction, and more rarely, supercritical carbon dioxide extraction. What each of these techniques has in common is that they act to separate the relatively low molecular weight oils (fatty acids) and oil-soluble vitamins and minerals present in the fruit or seed from the other materials that comprise the whole — fiber, protein, sugars and water.

Although I have seen various products advertising that their wheat germ oil contains “many proteins,” the evidence does not support this assertion. I wanted to get the opinion of an expert, so I consulted Professor Dunford of Oklahoma State University’s Department of Biosystems and Agricultural Engineering. He states that some solid granules or particles may get into the oil during the extraction process, which can lead to the inclusion of some small amount of protein in the oil. However, refined oils go through multiple steps of purification, including additional solvent extraction, filtration, and drying. For this reason, most of these oils used in cosmetics and personal care products should contain no more than trace amounts of protein, if any at all.

Relative concentration of the oil and trace amounts of protein should also be considered. If an oil comprises 1% by weight of a product (or even 5%) and contains a very small amount of protein, the protein concentration is negligible upon dilution of the oil into the product formula and even more so when diluted by water in application. It is my educated guess that the concentration of protein in a product or even in a direct application of the oil will be substantially less than in a protein-containing conditioner.

So what is in these oils that makes them special?

Wheat germ Oil

Wheat germ oil (”triticum vulgare” on most personal-care-product labels) is a very nutrient-rich plant-derived oil that contains a variety healthful substances. Among these are several different longer-chain fatty acids, long-chain saturated fatty alcohols such as octacosanol, and plentiful amounts of several vitamins and minerals. It is especially valued for its high content of tocopherols (Vitamin E), known to provide many health benefits.

Wheat germ does not differ from other triglyceride-derived oils, in that it contains a variety of fatty acids, the exact ratio of which will vary. The major components, in descending order of concentration, are:

• linoleic acid, an omega-6 essential fatty acid
• oleic acid
• palmitic acid
• linolenic acid, an omega-3 EFA

Several other fatty acids are present in very small quantities. The average molecular length of the major fatty acids in wheat germ oil is larger than that of coconut oil, which may give enhanced emollient benefits to wheat germ oil. The presence of the long-chain fatty alcohols also provides an additional boost to the conditioning and moisturizing properties of wheat germ oil. Based on its chemical profile, it seems like a great product to include in your home hair care routine.

Avocado Oil

Avocado oil is comprised mainly of oleic acid, palmitic acid, and linoleic acid. It also has several other fatty acids present. Its main fatty acid components are almost identical to those found in wheat germ oil, but the distribution differs. Avocado oil also contains significant amounts of Vitamins A, E, and D, again with Vitamin E being present in significant amounts. This oil is valued for its light feel and excellent emollient properties.

The magic ingredient in both oils?

Both wheat germ oil and avocado oil contain significant amounts of tocopherol, or Vitamin E. Vitamin E has been found to be especially beneficial as a moisturizing agent for both hair and skin due to its ability to penetration beneath the surface.. Studies have shown that tocopherol acetate (Vitamin E acetate) is absorbed directly into the hair cortex, where it can moisturize and plump the hair shaft. Deposition/penetration profiles have shown that significant amounts are absorbed, and that the effects are cumulative. Deposition is found to be increased on the surface of damaged hair, which is of significance for curly hair, which is more likely to have a damaged cuticle layer.

Another fascinating attribute of Vitamin E is that it has been found to possess properties that enable it to aid in the prevention and reversal of some forms of hair loss. As a powerful anti-oxidant, vitamin E can also protect the hair from damage caused by free radicals encountered due to exposure to UV radiation (sunlight), chemicals and pollutants.

The incorporation of natural, plant-based oils into a home hair care routine is a timeless tradition. It is so much fun to play with them, as there are so many with which to experiment and most of them smell really good! The two oils discussed in this article seem to be exceptional candidates due to the fatty alcohols present in wheat germ oil and the Vitamin E found in both of them. Unless one has a severe allergy to wheat protein in particular, I would also not be concerned about the presence of any trace amounts of protein molecules in the oil. So, once again, it is time to hit the health food store and stock up on some cooking and beauty products!

Sources:

Centerchem

Skolnik, P. Eaglstein, W.H., Ziboh, V.A. “Human Essential Fatty Acid Deficiency.” Arch Dermatol, 1977; 113 (7): 939-941 (ref. 6751). — fatty acids and hair loss

Tonya McKay

Polyquats are of major interest to curlies, specifically the removal of polyquats for those who avoid sulfate cleansers. Build up of any moisturizing or styling agent is a genuine problem because it can lead to limp curls, frizzy hair with a straw-like texture — and it can even lead to permanent damage in the form of breakage. For this reason, I persistently search for publications of studies done that specifically investigate this topic.

Polyquats (polyquaternium) are polymers frequently used in hair-care products to provide conditioning benefits to the hair. The trait they all share is that they are very large molecules with periodic positive charges located at different sites along the molecule. There are many different types of these cationic polymers, with widely varying molecular structures and charge densities (amount of positive charge/molecule). Each specific type of polyquaternium molecule is assigned a numeric designation, such as polyquaternium-4 or polyquaternium-11.

Some of these molecules are linear, like a snake or a single piece of spaghetti, while others have many branches like a tree. Most are fairly high molecular weight (in the 500,000 — 1,000,000 grams/mole range), which imparts the maximum conditioning benefits. A few of the polyquats are obtained via chemical modifications of naturally-derived polymers such as guar gum and cellulose. However, the majority are completely synthetic molecules developed and tested in laboratories, typically copolymers of various monomers selected to give the polymer the final desired properties. (If one is interested in further study, these monomers are often one of the following: vinyl pyrrolidone (VP), diallyl dimethyl ammonium chloride (DADMAC), dimethylaminoethyl methacrylate, and quaternized vinylimidazole (QVI).)

A BASF research group based in Germany published findings of a study they performed to compare the performance of several different common conditioning polyquats. They used several different test methods and sensory feedback tests to compare conditioning effectiveness and how easy it will be to remove removability of a common group of cationic polymers, including cationic guar gum, polyquaternium-7, polyquaternium-10, polyquaternium-11, and polyquaternium-44.

To determine conditioning effectiveness, they measured wet comb-ability of hair treated with each formula. (Wet comb-ability measures the forces required to comb through wet hair after application of the conditioning agent). They also surveyed consumer texture/sensory feedback on each type of polymer (typically accomplished in a small hair salon on site, where volunteers try different products on their hair and report how it feels to them). Atomic force microscopy was used to determine residual polyquat quantity on the hair after rinsing or washing with an anionic surfactant (such as sodium laureth sulfate).

The chemists reported that polyquaternium-44 led the pack by exhibiting superior conditioning benefits while simultaneously resisting build up. Cationic guar gum had the poorest performance in both regards. Polyquaternium-10 did not do as well in the conditioning efficacy analyses, but proved to also be easily removable. Polyquaternium-7 and polyquaternium-11 were somewhere in the middle of the group.

There were several interesting things to be gleaned from the behavior of polyquaterium-44. This is a completely synthetic, branched copolymer, of fairly high molecular weight, and fairly low charge density. Branched polymers like this are more coiled when in aqueous solution, unlike the more extended conformation adopted by their linear counterparts. For this reason, they are more easily deposited onto the surface of the hair, where the positively charged moieties bind to the protein surface.

Figure 1. Conformation of two different polymer structures in water — a linear polymer on the left and a branched polymer on the right.

The BASF chemists hypothesize that because of the low charge density of this particular polymer, much of the structure actually extends away from the hair surface in loops and coils. These little wiggly bits would act to reduce friction between adjacent hairs, which would reduce tangling and increase ease of comb-ability. This configuration is also credited with how easy it is to remove with a water rinse or shampoo rinse. Many cationic polymers resist removal with even the most harsh shampoos, so this is very interesting behavior.

Another research and development group observed similar behavior with a high molecular weight, branched and lightly crosslinked cationic polymer. This polymer displayed conditioning benefits superior to other cationic polymers when used in relaxer solutions. The inventors discussed data that supports that this polymer penetrated the hair cuticle due to its being open during the chemical relaxing process. Once inside, they believe it formed an elastic cushion inside the hair that provided lasting strength and elasticity to the hair. They also found that this crosslinked, non-linear material was more readily removed from the hair surface than other types of cationic conditioners, which also supports the findings of the BASF group.

The take-home message of this article is that products containing polyquat-44 will give you the best results compared to those formulated with other types of cationic polymers. It provides fantastic detangling and moisturizing benefits and detaches from the surface of the hair easily. Products with polyquat-10 are also a pretty safe choice for those on low-shampoo plans. It would be wise to keep in mind though that other polyquats as well as positively-charged silicones such as amodimethicone may be much more difficult to remove from your hair. As always, your mileage may vary, so don’t be afraid to experiment with products and ingredients!

Sources:

Hössel, Dieing, Nörenberg, Pfau, & Sander (BASF Aktiengesellschaft, Ludwigshafen, Germany), Conditioning Polymers in Today’s Shampoo Formulations; Efficacy, Mechanism and Test Methods, International Journal of Cosmetic Science, Vol. 22, No. 1, pg. 1-10, 2000

Woodruff, John, Formulators; it is time to widen your horizons, Paper given before the Society of Cosmetic Scientists, Chepstow, 2000

Agent: Joann Villamizar Ciba Corporation/patent Department - Tarrytown, NY, US
Inventors: Emily Crisp Bazemore, Rhonda F. Tsotsoros, Zhiqiang Song, Jianwen Mao
USPTO Application #: 20080138307, Use of high molecular weight crosslinked, water-soluble cationic polymers in hair care formulations

As we head into springtime, many curlies apprehensively anticipate the return of humidity — and frizz.

Weather is a constant variable that can toss a kink into the best of hair days. Who among us hasn’t left the house with perfectly coiffed curls, only to step out into a hot, sticky afternoon or a damp, foggy morning and see our hair lose all recognizable shape, inflate to twice its normal size and develop the texture of a piece of steel wool?

Wouldn’t it be spectacular if there was some crystal ball that could tell us each morning what the weather patterns would be and what exact products to use that would enable us to circumvent this seemingly unavoidable hair disaster? Although that might not be realistic, there are some clues available to us in the morning weather report or on NaturallyCurly’s Frizz Forecast. Learning some basic facts about humidity, humectants and the dew point can arm you with the the knowledge you need to select the right types of products to keep your curls looking their best, whether the weather is bone dry or warm and muggy.

50 Ways to say “Humidity”

I am neither a meteorologist nor an expert in the thermodynamics of gaseous mixtures, but I am going to tackle this topic even though it makes my brain hurt. Water coexists in the atmosphere with the gaseous mixture (primarily oxygen and nitrogen) that makes up our air. We all are aware of the fluctuating levels of moisture in our air — especially those of us living here in the great southern swamplands of the United States.

A description of the moisture content in the air can be expressed using different terms and based upon various calculations. The two most familiar to us are relative humidity and dew point, which are both typically disclosed in our local daily weather report. Even armed with all this information, it can be confusing for one to understand just exactly how humid it is.

Relative humidity

Relative humidity expresses the relationship between the vapor pressure or vapor density (g/m3) of the water in the air at a specific temperature versus the saturated vapor pressure of water at that temperature.

RH = (actual H2O vapor pressure/saturated H2O vapor pressure) x 100

The saturated vapor pressure for water changes substantially with temperature. So as the temperature increases or decreases, the value for relative humidity changes, even if the overall water content in the air remains unchanged.

Example: We have an actual vapor density of 6.6 g/m3, and a temperature of 86°F. The saturated vapor density for water at this temperature is approximately 30.4 g/m3. This gives a relative humidity of approximately 21.7 percent. If the temperature increases to 98.6, the saturated vapor density increases to 44 g/m3, and the relative humidity becomes 15 percent. Conversely, if the temperature were to decrease substantially to 55°F, the saturated water density decreases to 11.35, and the RH increases to a value of 50 percent! If the temperature is gradually decreased to approximately 37°F, the relative humidity approaches 100 percent.

(See this site for a great chart and all sorts of additional information).

Dew Point

Oxygen and nitrogen are always gases at the temperatures found in our atmosphere, and the molecules bounce around in the air exhibiting ideal gas behavior (conforming to certain thermodynamic laws). Water, with its relatively high boiling point, exists in all of its phases at our atmospheric temperatures. Primarily, in our atmosphere, it is constantly exchanging between its liquid state and its gaseous state. One way of thinking about dew point is that it is the temperature at which the number of gaseous water molecules being formed is equal to the number of liquid water molecules being formed (Evaporation rate = condensation rate). When the temperature reaches the dew point, the relative humidity is 100 percent. If the temperature decreases below the dew point, water must condense out of the air, and fog, dew, or clouds are formed.

We can see by a quick review of our previous example that had we chosen a greater value for our actual water density (meaning a higher level of water in the air), our relative humidity values would all have been higher, and our dew point would also be shifted to a higher value.

So we can conclude that a higher value for our dew point necessarily means a higher concentration of water vapor in the atmosphere, and a lower dew point means less moisture is in the air.

A common question among curlies is at which dew points are humectants helpful and desirable, and at which dew points are they perhaps harmful and undesirable? Before answering that question, let’s review humectants and touch on “anti-humectants” as well.

Humectants

We have spent significant time in the past discussing the chemical and physical nature of humectants and their relevance to the health and beauty of curly hair. To summarize quickly, humectants are molecules that possess atoms and groups of atoms that attract and bind water to themselves. They can have benefits and drawbacks for curly hair, and their performance is often very dependent upon the amount of moisture in the environment. This variable performance is due to the driving force in nature to reach and maintain a state of equilibrium.

Dry hair, placed in a wet, humid environment, quickly absorbs water from the air. Unprotected hair can quickly lose all of its internal moisture and become very dry in an arid environment. Humectants applied to the hair draw water to themselves from whichever source is greater — the atmosphere or the hair.

For more in-depth information on this topic, read this article.

What is an Anti-humectant?

An ingredient may be called an anti-humectant if it fulfills several requirements. First, it must not be hygroscopic, meaning it must not possess molecular traits that cause it to attract water molecules to itself. Second, it must be water repellent, which necessarily means insoluble in water. This property allows it to lock out or prevent the intrusion of moisture into the hair from a humid environment. Additionally, these ingredients typically coat, flatten, and seal the external cuticle layer of the hair strands. The anti-humectant ingredient will most likely be higher on the list of ingredients, and may be problematic for those on a no-poo routine.

In many formulations, the ingredients used for this anti-humectant task are silicones. This is because they not only perform the anti-humectant duties in a superior manner, but they also provide excellent lubrication of the hair and add a high degree of gloss (shine). Esters (such as isopropyl palmitate) are another category of ingredient used for their water-resistant properties in products designed to function well in high humidity climates. There are also many natural ingredients that work well for this purpose, such as hydrogenated castor oil, beeswax, and plant triglycerides such as coconut oil, palm oil, olive oil, and shea butter. I have included the ingredient lists for three different hair pomades and anti-humectant products that I found interesting.

MOP Glisten High Shine Pomade

Ingredients: Aloe Barbadensis Leaf Juice, Hydroabietyl Alcohol (Gum Rosin), Hydrogenated Castor Oil, Caprylic/Capric/ Stearic Triglyceride (Coconut/Palm), Beeswax (Cera Alba), Lanolin, Hydrogenated Rosin (Pine Tree Sap), PEG-40 Hydrogenated Castor Oil, Cocos Nucifera (Coconut) Oil, Lanolin Wax (Lanolin Cera), PEG-8 Beeswax, PEG-10 Soy Sterol (Soy), Butyrospermum Parkii (Shea Butter), Wheat Germ Glycerides, PEG-60 Almond Glycerides, Limnanthes Alba (Meadowfoam) Seed Oil, Olea Europaea (Olive) Fruit Oil, Humulus Lupulus (Hops) Extracts (3), Urtica Dioica (Nettle) Extracts (3), Cymbopogon Schoenanthus Extract (3), Fragrance (Parfum), Methylparaben, Ethylparaben, Propylparaben, Butylparaben, Phenoxyethanol, Isobutylparaben. [Source: (1) CertifiedOrganic in accordance with the California Food Act of 1990. (3) Certified Organic by Quality Assurance International.]

Hair Pomade by John Masters Organics

Ingredients: Extra virgin olive oil, organic beeswax, mango butter, babassu oil, jojoba, wheat germ oil, pure essential oils of bay laurel, cedar atlas, fir balsam and massoia, vitamins A, C & E. Certified Organic Ingredients.

Aveda Brilliant Anti-Humectant Pomade

Ingredients: Caprylic/Capric Triglyceride; Isopropyl Palmitate; C18-36 Acid Triglyceride; Bis-Diglyceryl Polyacyladipate-1; Bis-Diglyceryl Polacyladipate-2; Castor (Ricinus Communis) Oil; Phenyl Trimethicone; Cyclomethicone; Fragrance (Parfum); Glyceryl Laurate; Rice (Oryza Sativa) Bran Oil

The Relationship Between Humectants and Dew Point

It would be great if there were a magical mathematical formula to tell you exactly which ingredients to use in which temperature and humidity conditions. The best I can do is provide you with some loose recommendations on that topic. As always, you will need to do some experimentation with your own hair to find the combination of conditions and product that give the results you prefer.

If the dew point is below 35°F or so, the moisture content in the air is sufficiently low that a humectant applied to your hair might be irresistibly drawn to the moisture in your hair and make every attempt to steal it from you (by drawing it out of your hair and binding it to itself). This can result in dry, fly-away hair, split ends, and broken strands. This effect can often be compensated for by using plenty of moisturizing products, not over-drying your hair (leave it somewhat moist after washing), and layering leave-in conditioners with humectant-containing styling product.

Curly hair seems to really thrive in moderate climactic conditions, and dew point ranges of approximately 35°F to 50°F seem to be optimal. In this type of weather, most curlies find that they can get really pleasant results by using products that contain some humectants. There is just enough moisture in the air that the humectants can grab a little from the environment, which can enhance the curl and create a bouncy feeling to the hair.

When the dew point for your area is at 60°F or above, it might be a good idea to apply some product with anti-humectant properties. These products will seal the hair shaft, flatten the cuticle and prevent atmospheric moisture from absorbing into the interior of your strands. Most of these products will contain ingredients that are water insoluble. However, many of these products contain ingredients which are easily removed with an extremely mild shampoo or perhaps even a thorough conditioner wash.

The key to having the best curls in any weather is to have extremely well-hydrated and moisturized hair. This will protect your hair from losing too much moisture in dry weather, and it will prevent your hair from absorbing excess moisture in humid conditions. Another important factor is the overall condition of your hair. Hair that is damaged will necessarily be more porous, and thus more susceptible to climactic conditions. Smooth strands with a sealed, flat cuticle layer will be naturally more impervious to atmospheric conditions as well.

Tonya McKay

Propylene glycol is an ingredient found in many personal-care products, including shampoos, hair conditioners, and leave-in styling products. It is widely used because of its relatively low cost and versatile nature. Its inclusion in a formula can fulfill a variety of purposes, which makes it a popular choice by the cosmetics chemist. However, some manufacturers have recently made the decision to no longer include propylene glycol in their products.

My speculation is that this is possibly due to misinformation and propaganda circulated on the Internet, and elsewhere in the interest of marketing “natural” products. I am an avid supporter of using natural products whenever possible. and of avoiding putting toxins into our bodies whenever possible or practical. But I get frustrated by the dissemination of inaccurate and incomplete information in an attempt to frighten consumers into using different products. In this article, I seek to clear up some misconceptions about this chemical.

The Chemical Facts About Propylene Glycol:

Propylene glycol (also known as 1,2 propanediol) is a relatively small molecule with two alcohol (hydroxyl) groups (-OH). It is a colorless and odorless liquid and is completely water-soluble. PG is a synthetic product obtained from the hydration of propylene oxide, which is derived from petroleum products. I do not personally consider a petroleum-sourced product to be a bad thing in and of itself, as I consider the final structure and its properties to be more relevant than the source, unless residual contamination is a legitimate concern.

Molecular model of propylene glycol

The FDA has categorized propylene glycol as “Generally Recognized as Safe.” There is little to no skin irritation or sensitization even with prolonged direct exposure to the undiluted chemical. Irritation to the eye or respiratory system in the event of direct contact is mild and transitory, meaning it subsides quickly once the area is flushed. The MSDS recommends avoiding direct handling due to potential irritation, which is a smart recommendation for any chemical. But is not necessarily an indication of level of toxicity. It is important to remember that in the chemical industry, where a worker is exposed to continuous and possibly large quantities of a chemical in its concentrated form, it is imperative to use the strongest safety precautions possible. Although many sites would have you believe differently, this simply is not relevant to consumers using a product by the teaspoonful that “might” contain a few percent by weight of propylene glycol (if that much).

An interesting fact about propylene glycol is that it is non-toxic when ingested even in reasonably large amounts. Unlike its dangerous and frequently lethal cousin, ethylene glycol, PG is easily metabolized by the liver into normal products of the citric acid metabolic cycle, which are completely nontoxic to the body. Approximately 45 percent of any ingested PG is excreted directly from the body and never even comes into contact with the liver. The elimination half-life for propylene glycol is approximately four hours, and there is no bioaccumulation (buildup in the body over time). A few rare incidents have occurred where a person ingested a large quantity of propylene glycol and suffered some liver and neurological effects as a result, but these were short-lived and subsided once the material was metabolized and excreted.

Metabolic Cycle for Propylene Glycol:

Propylene glycol → lactic acid → pyruvic acid → CO2 + water

Both experimental and anecdotal evidence to date indicate PG to be completely non-carcinogenic, despite its “petroleum-based” origin. In a very interesting study, some unfortunate rats were fed propylene glycol at amounts equal to 5% of all of their food intake every day for two years, which is a pretty huge volume over a large portion of their lifetime. There were no observable effects on their health or behavior.

Another frequently cited concern about propylene glycol is its use as a component of antifreeze, especially in applications such as the airline industry for de-icing wings and runways. Many of the articles I have found online make a point to highlight the fact that PG is “antifreeze,” a term which has many negative connotations in the minds of people who have heard of the significant and potentially fatal dangers of “antifreeze.” This reputation is well-deserved for ethylene glycol, an extremely toxic material that was commonly found in automotive and other antifreeze solutions. However, propylene glycol has become a common replacement for ethylene glycol in many commercially available antifreeze formulations because it is much safer than ethylene glycol.

Another relevant point is that the word “antifreeze,” frequently used to alarm consumers, is simply a scientific term used to describe a completely innocuous process — the lowering or depression of the freezing point of a liquid. An example of this process is the application of salt to roads and walkways in a snow storm. This helps melt snow and ice and prevent development of dangerous icy conditions. The salt accomplishes this by lowering the freezing point of water. This is an example of a “safe” chemical being used as antifreeze. My point here is to not be alarmed by the term antifreeze or by the chemical, propylene glycol. While few chemicals are entirely without risk, propylene glycol is considered to be safe at the low concentrations used in personal care products and even food products.

What is propylene glycol used for in personal care products?

• It is a very effective humectant
• It is a solvent or carrier agent for fragrances and preservatives.
• It can be used as an emulsifier or co-surfactant.
• It is used as a solvent for pigments in cosmetics.
• It can be used as a preservative due to its anti-fungal and anti-microbial properties.
• It is frequently used in deodorants and antiperspirants.
• It is found in hand cleansers and disinfecting gels.
• It is a common additive in shaving creams and gels.

I think for those of us with curly hair, propylene glycol’s main benefit is the fact that it is a humectant, and a pretty effective one at that.

How will propylene glycol affect my hair?

The application of propylene glycol that is most relevant to those of us with curly hair is as a humectant. All the usual cautions apply with regard to its capabilities to attract water to the hair from the environment or to draw water from the hair to itself. In other words, unless you have the perfect atmospheric conditions, you may experience problems with this ingredient. Propylene glycol is a completely water-soluble material that will not build up on the hair, regardless of whether a low-poo or no-poo routine is used. It is also important to note that it is a diol with low volatility, so it will not evaporate easily and cause dry hair in the manner of low molecular weight alcohols such as SD alcohol and isopropyl alcohol.

Overall, after reviewing the available information from diverse sources, my opinion is that propylene glycol should not be a feared ingredient. If product manufacturers are finding replacement ingredients to fulfill the same purposes in their formulas served by propylene glycol, I see no harm in that. However, I hesitate to support marketing materials that use this as a selling point.

As a curly, it would be wise to be aware if you are using products that contain this ingredient, just in case you observe increased frizz or dryness. Always be certain you use plenty of moisturizing products to help lock moisture into your hair shaft, which can help prevent any potential problems caused by a humectant.

References

“Case Studies in Environmental Medicine (CSEM), Ethylene Glycol and Propylene Glycol Toxicity”
What is Propylene Glycol?
Gaunt, IF, Carpanini, FMB, Grasso, P and Lansdown, ABG, “Long-term toxicity of propylene glycol in rats, Food and Cosmetics Toxicology,” April 1972, 10(2), pages 151-162.
Dow
McKay, T. “Humidity, Humectants and Hair”, online publication, Aug. 2007