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.
Purified Spring Water
Japanese Honeysuckle Flower Extract
Tea Tree Oil
Organic Sage Extract
Organic Burdock Root Extract
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.
The total cumulative charge is directly proportional to the total surface area of the crystal. As particle size decreases, the overall surface area increases, and thus the particles become more highly negatively charged. This property makes these materials very interesting for nanotechnological research and applications.
Natural or chemical?
A positive metallic ion (usually either sodium or calcium and sometimes magnesium) is associated with each crystalline face. These are known as exchangeable ions, as they vary according to the source of the mineral. The effect of these cations is to significantly reduce the overall negative charge of the platelets. Montmorillonite clay is quite hydrophilic and readily attracts and adsorbs water to itself. When hydrated, bentonite crystals aggregate together to form a three-dimensional structure known as a house of cards, with a layer of water between each card.
When the positive counterion is sodium, these clays retain a higher degree of negative charge and are thus extremely hygroscopic. In this form they swell tremendously due to absorption of large quantities of water molecules, which can be hazardous in biological applications. However, sodium bentonite can be very useful in many other applications, particularly in the mining and petroleum industries. Calcium bentonite is the preferred form for most cosmetic and pharmaceutical uses, as it still swells in aqueous systems, but it is not quite so hygroscopic as the sodium form.
The unique ionic, three-dimensional, sandwich-like structures of calcium bentonite impart extremely interesting and useful properties to these materials. They are excellent colloid dispersant agents and highly effective emulsifiers as they can trap oils in the layers between platelets. They also can enhance the structures of micelles in solution and aid in the development of liquid crystalline structures, such as vesicles.
Bentonite clays are often used as viscosity modifiers for fluid systems that require thickening but that are also expected to be easily spreadable or dispensable. Consider toothpaste. It must be sufficiently viscous to fill out and remain inside the tube, but it must also be easily squeezed and dispensed onto a toothbrush. Bentonite clays are pseudoplastic materials (those with non-Newtonian properties) that exhibit this type of thixotropic behavior, which means that the viscosity of the system decreases over time with a constant applied shear force.
The properties of bentonite also make it very compatible with ingredients typically found in cosmetics and hair and skin care products, such as anionic and nonionic surfactants, oils, fats, salts, and waxes. They are highly effective at stabilizing oil-in-water emulsions, and for this reason make excellent emulsifying agents for many applications.
The smectite clay structure and ionic properties of bentonite are also useful for the removal of heavy metal toxins as well as certain pathogens that are positively-charged. These materials are adsorbed onto the negative surface of the platelets, and effectively carried away inside the "sandwich" when the product is rinsed or digested.
Oil extracts are often healthy for the hair
So, when examining the ingredient list of Scalpure once more, knowing what we now know about calcium bentonite, it becomes evident that its primary practical function in this product is as an emulsifier for the various essential oils, stabilizer, and viscosity modifier. However, in addition to these worthwhile and practical properties, the clay also acts as an exfoliant for the scalp and a detoxifier for the scalp and hair. The product makers claim that it is capable of removing toxins and metals below the skin's surface, thereby improving the health of the hair follicles and thus increasing hair growth. While I can neither confirm nor deny that claim, I can state with a fair level of confidence that this is at the very least being accomplished on the surface of the scalp, which may be sufficient to lend improvement to a situation of an oily scalp, dry and flaky scalp, or one with buildup of toxins.
It seems to me that this product could be very useful for one to incorporate into the hair care routine. However, for the sake of curly hair, I might caution being too rough with the hair when the product is being applied or while it is on the hair. The reason for this caution is that the clay particles could possibly roughen up the cuticle if care is not taken in the handling of the hair when in contact with these particles. (Doesn't it always seem to come down to the cuticle and its protection?)
Another possible red flag I could see with these types of products for those with curly hair is the potential for the hair to become dried out, or essentially desiccated. Remember that calcium bentonite is hygroscopic and does attract water to itself (not to the extent that sodium bentonite does), so it is feasible that it could remove water from the cortex of the hair. Hair that is more porous would be more susceptible to this problem, so perhaps these consumers should use the product with caution or do a deep-conditioning treatment post-application. Leaving the product on for too long would also increase the potential for this phenomenon, so I recommend shorter exposures. I think for most people, with proper use, this product should be just fine and possibly quite beneficial.