CurlChemist

Accumulation of mineral scale on surfaces due to hard water build up is an unfortunately common and truly aggravating problem. Most people have experienced the joys of living with hard water: cloudy, spotty dishes coming out of the dishwasher, diminished performance of coffeemakers, clogged or broken pipes and washing machines with an unpleasant odor that don’t work properly, turning clothes and towels dingy grey or a rust-tinged color.

Hair is susceptible to this menace as well, becoming dull, limp, or frizzy and more prone to tangles and hair breakage due to accumulation of minerals causing hair build up. Certain strong shampoos, such as clarifying or chelating ones, are marketed as solutions to some of this, but are there any options for those avoiding sulfate-based surfactants? As always, the answer to that question lies in the chemistry and materials science of the system.

Why Hard Water Creates Hair Build Up

If you have hard water, removing hair build up should be part of your hair care routine.

Hard water contains significant quantities of dissolved minerals, such as iron, calcium, magnesium, and silicon. These metals can react with substances in soaps and shampoos and reduce the effectiveness of those products’ cleansing properties, making it necessary to use more of the cleanser. But, even more disturbing, is that fact that the reaction products precipitate out of the solution and deposit onto the surface of your hair, where they bind with the negatively charged surface. This is what is typically referred to as mineral scale, which conjures up a bit of a mental image, if one considers it. Picture hard fish scales covering your hair, creating a rough surface that prevents moisture from penetrating the hair shaft, and you won’t be too far removed from the reality.

These deposits also attract and trap organic matter such as grease and dirt. This leads to hair that becomes increasingly difficult to deal with. It becomes dull instead of glossy, loses curl retention capability, is more prone to formation of snarls and tangles and is more easily damaged. It can even lead to the development of an unpleasant odor to the hair, particularly in dreadlocks.

Clearly, this kind of hair build up is not a trivial issue and should be addressed as a normal part of a person’s hair care routine.

How to Prevent Hair Build Up

The absolute best method for dealing with hard water is to prevent hair build up in the first place. One can do this by utilizing a good water filter that removes the unwanted metal ions from the water. Another technique is to use a chelating shampoo regularly, which has molecules in it such as EDTA, or acetic or citric acid. These acids bind with the metals in the water as you are washing your hair and are then rinsed away instead of depositing onto the surface of your hair. These shampoos can be harsh, though, and should always be followed up with a good conditioner, but even then, they may be damaging to curly hair if used too often.

Vinegar rinses can possibly help loosen mineral scale so it can be rinsed, and it definitely helps dissolve some of the trapped organic matter that can be lurking in the residue. Clarifying shampoos can also help remove hair build up. It is not clear whether they actually remove mineral scale from hair, but they definitely can provide deep cleaning of any other matter adhering to the surface because of the mineral scale.

Chelating shampoos may be able to dissolve the mineral scale and help remove it from the hair. The Beauty Brains, a site run by cosmetic chemist/consultant Perry Romanowski, states their skepticism as to whether this works at all, which makes me yearn, yet again, for a lab with some really expensive equipment so I could run some studies, both to satisfy my own curiosity and so I could also give you all a definitive answer.

Gentle shampoos with surfactants designed to provide mild cleansing are undoubtedly capable of removing organic material and hair build up. This includes surfactants such as sodium cocoyl isethionate and coco betaine. However, it seems unlikely that these would have the ability to remove mineral scale by themselves. Fortunately, there are definitely some shampoos that contain mild surfactants, no added conditioning agents, and acids that are thought to aid in removal of hard water hair build up.

Final Thoughts

Since it is so evident that curly hair performs absolutely at its best when it has both a clean surface and a well-moisturized cortex, it seems imperative that you take some sort of measure to prevent or remove hair build up caused by hard water. The installation of a water softener or filter seems to be the best and most proactive solution. However, there are other alternatives, such as rinsing with vinegar and using chelating shampoos. It is of utmost importance that an excellent conditioner be used whenever one uses strong products like this on the hair, so don’t skimp on that step.

The science of hair care has been a lively area of research and development for the past 50 years or more. Tremendous strides were made in the past two decades alone, thanks to advances in polymer and colloid chemistry. These advances were found in both the area of designing and producing extremely complex polymeric molecules and also in the area of understanding the mechanisms by which these molecules provide benefit. The incorporation of highly sophisticated polymers and polymer combinations into formulations has yielded curly hair products capable of truly protecting and enhancing hair, and efforts to optimize existing polymers and to synthesize new types are ongoing.

Silicones

Many currently available moisturizing curly hair products rely heavily upon the use of cationic polymers and silicone-based polymers as conditioning agents. Silicone polymers provide excellent smoothing of the cuticle, impart shine, protect hair from thermal damage, increase longevity of hair color and yield positive tactile feel to hair. Cationic polymers can work together with silicones to enhance their performance in conditioning shampoos. They can also work alone to provide excellent conditioning benefits, including superior combing force reduction.

However, these ingredients and the products that contain them have recently waned in popularity with consumers, primarily due to concerns about buildup of those substances on hair. This trend has not gone unnoticed in an extremely market-responsive industry, and has, in fact, been a huge driving force behind research and development efforts. These projects have been ongoing, both at raw materials suppliers and finished good manufacturers, with the objective to develop and produce replacement polymers and silicone-free formulas.

One such project recently came to fruition when Dow Personal Care, a subsidiary of Dow Chemical, released its new conditioning platform, EcoSmooth Polymer Technologies.

Their product literature states that the platform is comprised of two types of polymers: EcoSmooth Silk and EcoSmooth Satin, which they claim will “reinvent conditioning.” An examination of these polymers and how they compare to more commonly utilized polymeric conditioning agents may provide curlies with insight to help them decide whether or not to give these materials a try.

EcoSmooth Silk

EcoSmooth Silk is a polyolefin water insoluble copolymer emulsified using a proprietary acrylic-based polymer dispersant with the INCI name: ethylene/octene copolymer and ethylene/sodium acrylate copolymer. This polymer is marketed as a replacement for silicone.

Marketing and technical literature published by Dow Personal Care describes EcoSmooth Silk as “a non-cationic technology that matches silicone in wet and dry combing and minimizes hair breakage.”

Although this polymer is a hydrophobic one (i.e. not water soluble), Dow reports that they did not observe evidence of appreciable buildup after repeated use. The method they used to make this assertion was based upon volume of the hair after repeat application. With silicones, which do build up over time, hair volume is found to diminish. Hair treated with the EcoSmooth polymer was found to have greater volume after multiple applications than that treated with silicones.

No actual chemical analysis or surface analysis of the hair was reported or described to substantiate this claim, although it may exist. This polymer should be removable using a mild shampoo, but shampoo-free users may wish to proceed with caution.

EcoSmooth Satin

EcoSmooth Satin is a non-cationic conditioning polymer with the INCI name: Ethylene/Sodium Acrylate Copolymer. It can be used to replace cationic polymers such as polyquaternium-7 and guar.

Dow claims that it provides equivalent sensory and foaming performance to those two polymers and that it provides superior performance on damaged European hair in particular. This means that the tactile feel is better to the consumer both during and after use.

When compared to cationic guar applied to damaged hair, EcoSmooth Satin was found to demonstrate a superior ability to reduce wet combing forces, making it easier to detangle hair and to significantly reduce the percent breakage of hair.

Satin is a water-soluble anionic polymer in solution that deposits onto the surface of the hair via a dilution deposition mechanism, where it binds to hair via hydrophobic interactions. Cationic polymers bind electrostatically to the surface of negatively charged hair via a charge-charge interaction. So, while both types of polymers are water soluble, Satin should be more easily removed from the surface of hair due to weaker interactions between the hair and the polymer.

For this reason, it seems reasonable to expect a buildup free experience when using curly hair products containing this polymer, presuming other ingredients in the formula are not prone to build up themselves.

Wrap-up

It is truly exciting to observe the sophisticated application of polymer science to the development and optimization of hair conditioning products. Silicones and cationic polymers have provided formulators with seemingly endless formulas that have truly stellar performance on hair.

Yet, there are many more possibilities, as Dow has clearly demonstrated with the launch of EcoSmooth Polymer Technologies. These polymers appear to be promising as conditioners used in curly hair products, as they seem to be less prone to buildup and also have demonstrated an ability to reduce breakage.

It will be interesting to see how these materials work in commercially available products, and also to see what other polymers will emerge onto the scene in the future.

Illustration of oil droplets suspended in water (emulsion)

Illustration of a micelle

Depiction of a sterically stabilized emulsion

Recently, an insightful reader asked whether a certain styling product advertised as “water-soluble” could possibly be so. The specific reason for the inquiry was the presence of petrolatum and mineral oil near the top of the ingredients list. Of course, my reflexive response to this question is “no.” Petrolatum and mineral oil are both decidedly hydrophobic materials, and they are not, nor will they ever be, water-soluble. However, this product is definitely described in the marketing material as being water-soluble, so it seemed worthwhile to give this a closer look and see what answers may be found in the chemistry of the formulation.

The product in question is Curlisto’s Unruly Paste, recommended for use on dry hair to provide curl definition, shine, and to tame frizz. It is described on their website as being non-sticky, non-oily, and “water-soluble.”

It is possible to glean a good bit of useful information about Unruly Paste by analyzing the ingredients list. Unlike many similar types of products, this is a water-based styling crème. It contains humectants (propylene glycol), a water soluble fixative polymer (VP/VA copolymer), a significant percentage of higher molecular weight oils/waxes (petrolatum, mineral oil, and ozokerite – a mineral wax mined from the earth), a non-water soluble silicone for shine and smoothing, and a large quantity of emulsifying agents.

Micelles are aggregates of surfactant molecules in water, comprised of an exterior shell of the hydrophilic portion of the surfactant and a hydrophobic center containing the non-polar segment of the surfactant. In this product, the surfactants form micelles that contain the mineral oil, petrolatum, and/or ozokerite in their core.

The nonionic emulsifying agents prevent coagulation and phase separation of the waxes by a mechanism known as steric stabilization. This is where the hydrophilic portions of the surfactant molecule extend out into the aqueous solution and form a bit of a tangle around the micellar aggregate. This tangle physically prevents micelles from coming together and joining to form bigger micelles, a phenomenon that would eventually destabilize the system and result in phase separation.

Technically, the non-polar waxes are solubilized or dispersed into the water using these emulsifying agents and are water soluble while in these aggregate forms. To reiterate, they are only soluble by nature of their containment within the interior of the micelles formed by the surfactants. (You may recall that we have had similar discussions about amodimethicone, as used in certain shampoos and conditioners.) These types of mixtures are called emulsions, because they are not solutions by proper definition.

Once the product is applied to the hair, the micellar structures are disrupted, the waxes are deposited onto the surface of the hair, and the water from the product evaporates into the air. Since this is a leave-in product, the surfactants remain on the surface of the hair even after the water evaporates, but they no longer serve much purpose except to perhaps attract water molecules to the hair from the environment.

The question is when hair that has been treated with this crème is immersed in water, will the emulsifying agents somehow re-form the micellar structures and re-absorb the waxes into their cores, allowing them to be rinsed away? It is my opinion that this scenario is highly unlikely, as the original process of preparing the product relies heavily upon proper order of addition of ingredients, judicious mixing and agitation, as well as the application of heat in order to form these types of structures in the first place.

However, it is possible that if one were to use a very mild shampoo or even a light conditioning product and gently agitated the hair, that the residual emulsifying agents on the hair might be able to aid in removal of the waxes from the surface of the hair. Generally, one would need to use quite potent shampoos to remove petrolatum and mineral oil from hair, and it would probably be necessary to rinse and repeat.

Final thoughts

Thus, it would seem possible that this method could alleviate some of the accumulation that inevitably occurs from use of typical products that rely upon these types of waxy ingredients. “Water-soluble,” though, seems to be a bit of a marketing stretch.

One of the primary indicators of the health of your hair is its elasticity. Healthy hair has a high level of elasticity, which gives it body, bounce and curl formation. Elasticity makes it possible to style hair and also is responsible for curl retention. But what exactly does the term elasticity mean? We know it has to do with the stretchiness of our hair, and we know it is a desirable property, but it may not be entirely clear what it is.

Also, what contributes to elasticity of hair, and how can we maintain or improve the quality in our own locks? These are important questions, and as always, much insight can be gleaned by an examination of the fundamental principles as well as the molecular structures that make up the hair.

What Does Elasticity Mean?

Elasticity is a term used to describe how a material responds to the application and removal of a specific type of mechanical load (pulling and/or bending). When a stress (force per unit area) is applied to a material, it stretches a certain amount beyond is original length. This deformation is dependent upon the stiffness or rigidity of the material. The ratio of applied stress to the amount of deformation/elongation that occurs is called the elastic (or Young’s) modulus.

Rigid materials, such as iron, stretch very little with an applied force, while other materials, such as synthetic rubber, can stretch many times their original length without breaking. Dry hair can stretch to approximately 1.2 – 1.3 times its original length and still return to its dimensions, while wet hair is less rigid than dry hair and can stretch up to 1.5 times its length. Curly hair can stretch even than straight hair, as it is highly coiled in its relaxed state.

In the cosmetics and hair care industry, a continual stream of new products are introduced into the market. Most seem to be variations of whatever happens to be the current popular theme. On occasion though, new products emerge onto the scene bearing remarkable claims that demand closer examination.

One such recent case is the Nexxus Pro-Mend system, which the manufacturers assert can nourish hair and actually heal split ends. Who wouldn’t be intrigued by promises that the product could repair up to 92% of split ends in the first use? It seemed a sufficiently brazen claim to warrant some scientific detective work to determine if the claims are credible, and if so, what the chemical basis is for the reported miracle cure for split ends.

Too Good to Be True?

The initial response many may have when hearing such a claim is that it is preposterous. We have all been taught that hair is a “dead” protein, and that topical treatments such as hair products are incapable of providing anything other than cosmetic, superficial, and temporary benefit. However, our understanding of and facility with protein and polymer chemistry has been continually advancing in unexpected and oftentimes brilliant ways. For this reason, I am willing to temporarily set aside my skepticism and entertain the notion that maybe someone has finally found a way to repair split ends without a pair of scissors.

There is a general procedure one can follow to gain fundamental insight into the technology behind a new product. The first step to understanding is to examine the ingredient list and look for anything new or unusual combinations of materials. Next, it is helpful to review the company’s marketing material and instructions for use of the product. Finally, one can gain a tremendous amount of valuable information by scouring the relevant technical literature and patents (even those of competitors or for products used for completely different applications).

Analysis of the Ingredients

Nexxus Pro-Mend Leave-In Treatment Cr̀eme Ingredients

Water, Phenyltrimethicone, Dimethicone, Stearamidopropyl Dimethylamine, Polyquaternium 37, Polyquaternium 28, Cetyl Alcohol, Glycerin, Cyclopentasiloxane, Aspartic Acid, Propylene Glycol, Dicaprylate/Dicaprate, Fragrance (Parfum), PPG 1 Trideceth 6, Glyceryl Stearate, PVM/MA Copolymer, Dimethiconol, DMDM Hydantoin, Disodium EDTA, Sodium Hydroxide, Hexylcinnamal, Butylphenyl Methylpropional, Limonene, Coumarin, Linalool, Alpha Isomethyl Ionone, Cocos Nucifera Oil (Coconut), Keratin Amino Acid,Jasminum Officinale Flower Extract (Jasmine)

I was slightly taken aback by the ingredients for the products in the Pro-Mend line, which were not exactly what I expected to see in a novel intense conditioning formula. The major components listed are silicones and polyquaternium conditioning agents. The use of cationic polymers (polyquaterniums) is not surprising, as they are selectively attracted to damaged areas of hair (which bear a negative charge). For this reason, they can be particularly useful in smoothing damaged cuticles and managing split ends. However, this is not a novel application of these materials. At first glance, nothing else jumped out as a likely character that would be able to repair split ends.

The first eight ingredients after water are found in many conditioning products, so no surprises there. After that are oils, emulsifiers, humectants, solvents, one fixative, and other common conditioning agents. But again, none of these ingredients are really known for doing anything terribly novel in terms of hair repair. Most are topical film-formers possessing varying ability to smooth, condition and protect the surface of the hair.

So, was that it? Was Pro-Mend merely another iteration in the long line of conditioning products available? Perhaps not. After further contemplation of the formula, I began to think there was more to these products than first meets the eye.

Several ingredients stood out in the list and nagged at my subconscious. Among these were Aspartic Acid, DMDM Hydantoin, Sodium Hydroxide, Hexylcinnamal, Butylphenyl Methylpropional, and Keratin Amino Acids. These ingredients are not uncommon and each has its own typical and often mundane purpose in a product. However, some of these are capable of performing double duty, and the presence of all of these ingredients together led me to have some suspicions as to how this product could possibly do the things they promised it could do. But, I needed more information.

Gray hair has a higher susceptibility to damage when exposed to UVA and UVB radiation.

Those with a significant amount of gray hair are keenly aware that it behaves differently than the rest of their tresses. By definition, gray hair is lacking color, leading to less luster and shine. It often doesn’t have the same curl pattern or texture as the rest of the hair, which can make it appear unruly. Gray hair may also seem drier and more prone to frizz. However, really well-kept gray hair can be quite attractive. It is very delicate, though, and is especially prone to photo degradation and yellowing when exposed to excessive amounts of sunlight. This tendency is of particular concern as spring approaches, and many plan to spend more time outdoors gardening, swimming, or just basking in the sunshine. Fortunately, being armed with knowledge of the unique risks of sun exposure to gray hair can make it possible to prevent damage and maintain a healthy head of hair. So what does science tell us about gray hair and ultraviolet rays?

Testing and Data

Researchers have done comparative studies on various physical and chemical properties of blonde, brown, and gray hair, both before and after UV irradiation. One notable study examined a wide array of properties, including tensile modulus, tensile strength, wet combing forces, degree of swelling in basic solution, cuticle abrasion, and dynamic contact angle. They also assessed changes in hair color with exposure to UV radiation. All of these properties provided them with indirect information about the biopolymeric structure of the hair strands and how they were affected by the experimental conditions.

What they found was that the gray hair had a much higher susceptibility to damage than did the brown hair when exposed to both UVA and UVB radiation. The samples had a higher loss of mechanical strength, greater color change (yellowing), increased cuticle damage, and exhibited a marked transition from being hydrophobic to hydrophilic at the surface of the hair strands. This meant the gray hair was more likely to exhibit signs of yellowing after exposure, to become more easily tangled, to lose moisture easily, and to break. It was evident to this group that gray hair requires protection if it is going to be in the sun for prolonged periods.

For this reason, these researchers also performed their study using two different UV absorbers that have been used successfully in skin care products. One was octyl methoxy cinnamate (OMC), a commonly utilized sunscreen additive, frequently found in hair care products marketed as being effective for color retention and sun protection. The other ingredient was cinnamidopropyltrimonium chloride (CATC), a quaternized (cationic) UV absorber. Each UV absorber was applied to the hair via a soak/rinse cycle in a simple shampoo-like solution of SLS/sunscreen. The samples were irradiated for specified periods of time and then run through all of the same testing as the ones previously discussed.

Budget conscious consumers have switched to less expensive hair care brands

Do-It-Yourself Hair?

Despite being generally rather stable, the personal care and cosmetics industry has not escaped the recession entirely unscathed. Budget-conscious consumers have sought out lower-priced alternatives to salon-based premium priced goods and services, and switched to the less expensive brands available at major retailers, online vendors, and health food stores. Many have elected to forego visits to the salon and do their own chemical processes, such as hair color, at home. The result of this trend has been a slight decrease in typical growth compared to previous years. Fortunately, examination of the current research and development focus in the industry reveals that this is a new opportunity for manufacturers to demonstrate their versatility and ability to meet the demands of their dynamic market.

Improving Quality at Lower Price Points

One response to the changing customer preferences has been the investment of research and development resources into new and improved products that target mass market price points. Recent strategies have included enhancing existing brands with the addition of new high performance additives, offering sulfate-free shampoos, expanding current product lines, and recategorizing products to target specific hair types (especially curly and ethnic hair). Providing consumers with better value by offering larger-sized packages of products has also been a popular approach. Another area where the industry has developed in response to customer preferences is the “green” market sector—where customers demand products with fewer petroleum-derived ingredients, more plant-based materials, and packaging and processes that are sustainable and environmentally conscientious.

As more consumers choose to dye and maintain their own hair color at home, do-it-yourself products have been the focus of intense research at multiple companies. The culmination of several years of work is the launching of several new home hair color lines that utilize foam delivery technology. John Frieda, Clairol, Henkel and Samy are all marketing these products, both in the United States and Europe.

All hair gels are not created equally

Don’t be a flake!

It is not uncommon for various users of the same hair gel to report different performance results, sometimes drastically so. It can be very unnerving and discouraging to try a popular, highly recommended hair gel, only to discover that your own hair becomes completely unmanageable or develops a case of highly unattractive white, flaky mess. What can be even more frustrating is the fact that the same product that yielded perfect hair one day might produce really undesirable properties another day. It can be discouraging enough to make a person question their ability to properly use a product, or perhaps even begin to think their hair is just flawed or something. However, there typically is a good reason for this type of unreliability, and it can be found by examining the ingredient list.

So, what is the source of this variability, and how can an ingredient-savvy person select a product that will yield a predictable outcome? The answer lies in the chemistry and materials science of the ingredients, of course, most specifically the polymers.

Scalpure

Recently, there has been some discussion in the curly haired community about products such as Scalpure, which marketed as a facial treatment for the scalp. The makers of such products maintain that that the products can provide a number of benefits to hair, such as stimulating hair growth, reducing excess oil production, and improving dandruff symptoms, among other things. These are rather bold claims, but perhaps are not without some scientific merit. The idea behind the development of this product is rooted (pardon the pun) in the theory that the health of our hair begins with the health and wellbeing of the scalp and follicles. As the makers of Scalpure say, “the scalp is the soil for the hair.” Examination of the ingredients list should provide us with some scientific insight into whether or not the treatment can possibly live up to these promises.

Most of the ingredients in this list are fairly self-explanatory. Purified spring water is the bulk solvent for the product, so it is not an oil-based treatment, which makes it easier to rinse out of the hair. The various essential oils and plant extracts in the list are all familiar to most of us and are commonly found in many products.

These types of oils can soothe dry skin, plump and smooth hair, stimulate blood flow to the scalp, improve circulation and thereby enhance cell growth in follicles, act as anti-inflammatory agents, and provide antimicrobial and antifungal benefits. These oils also have a lovely aroma, which can provide the user with a sense of emotional energy and well-being.

To me the fascinating ingredient in Scalpure is calcium bentonite, which is a crystalline inorganic material that is a member of the smectite clay family. It is sometimes known as Montmorillonite clay. Its chemical structure is hydrated sodium calcium aluminum magnesium silicate hydroxide, shown empirically as: (Na,Ca)0.33(Al,Mg)2(Si4O10)(OH)2·nH2O

This aluminosilicate clay is mined from various sites around the world, refined, purified, and then used as raw material for many different applications.

The crystalline structure of calcium bentonite is much like a playing card. The silicon-aluminum-oxygen crystal forms an ionically charged platelet structure. Typical platelet edge thickness is around one nanometer, while the face can be as much as several hundred nanometers across. The broad, flat surface is covered with negative charges, while the edges are very slightly positively charged. This lends an overall negative charge to these crystals.

Dear Tonya: Why is it that some products formulated with “gentle” surfactants and marketed as natural or sulfate-free actually seem to be more drying and damaging to my hair? I thought these products were supposed to be more gentle and kind to my fragile curls.

A: This question pops up frequently, and I have asked it myself when trying out new products without having really scrutinized the ingredients list. (Yes, even the CurlChemist sometimes buys things without much regard for the ingredients list, simply because the products look nice, smell nice, or have good promises on the package). Several factors are at play here.

Concentration of Cleansing Agent

It is possible that some of these sulfate-free shampoos contain very high percentages of surfactant, resulting in a product that is more effective at removing fatty acids and dirt from the scalp and hair. This can be disastrous for hair that is already fragile and that struggles with being too dry already. Unfortunately, it is not possible to determine this information by reading the ingredients list, as the labeling requirement is simply that the ingredients are listed in order of concentration—typically highest to lowest. Thus, the first surfactant on the list could be in the formula at 10%, 20%, or even 30% (or anything in between), and it would not be evident to the consumer.

Lack of gentle co-surfactants

Many products formulated with some of the stronger surfactants contain additional detergents called co-surfactants. These are typically materials such as cocamidopropyl betaine, fatty alcohols, and mild cationic surfactants. The mixture of these various surfactants act to diminish both the potential irritancy of the product and the oil stripping capability. The micelles formed in such mixed surfactant systems exhibit different physical and kinetic behaviors than those comprised of a single surfactant. The result is typically a milder formulation. Some of the products advertised as more pure or more gentle actually leave this important step out of their formulation.

Lack of fats/oils/conditioning agents

Good-quality cleansing products include moisturizing agents in their formulation that help to redeposit some oils onto the surface of the hair to prevent excessive drying from the washing process. Again, some of the simpler products that claim to be gentle may be missing this important component of the formulation.