Tonya McKay writes:
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.
Polymers are the large molecules used in hair gels to provide the styling and hold properties. When the gel is applied to the hair, the product spreads out evenly over the surface of the strands and creates clumps of hair that are attracted to one another via capillary and Van der Waals forces. The product dries to form a clear, shiny film that acts to encapsulate and hold the hair in place and give it form and lasting hold (also known as curl formation and retention). A variety of naturally derived, synthetic and combination polymers are used to this effect, and all have their inherent strengths and weaknesses.
Most formulations are a balancing act between pros and cons of the ingredients. In order to improve one property, it is typical to lose ground in another property. For instance, it is desirable for a product to provide strong hold, yet for the film to be durable and not brittle. It is desirable for a gel to resist humidity from the environment, but also for it to be water soluble and easily removed from hair. However, these objectives are naturally in conflict with one another. Polymers can give special advantages to formulators in this respect, as it is possible to tailor one to meet multiple requirements. Cost is often a limiting factor, though, as the more fancy and specialized a polymer is, the more difficult it can be to obtain in sufficient quantities and at a reasonable price.
So, what specifically causes white flaking? Some polymers form really strong films with high tensile strength that also adhere very well to the hair. These molecules are not very flexible, though, and when enough force is applied to the hair (touching the hair, scrunching, styling, wind), they will essentially shatter like glass into many small particles. These particles lose their clarity and become unattractive white flakes on the hair and scalp. This tends to be more of a problem in cold, dry weather.
PVP (poly n-vinyl-2-pyrrolidone)
A polymer that is notorious for having these issues is currently seeing an upsurge in usage amongst products targeted at curly-haired consumers, and that is PVP (poly n-vinyl-2-pyrrolidone). PVP is an excellent film-former, is relatively inexpensive, and most notably, is completely water soluble. The water solubility is extremely attractive to companies who wish to sell products to consumers who do not use shampoo or who use very mild shampoos, as it makes the gel easy to rinse. However, PVP can be very brittle and prone to flaking in cold dry weather. It also is hygroscopic and absorbs moisture from the air in humid climates, which can impart a tacky, sticky feel and lead to frizz and other unpleasantness. Clearly, a product which relies on PVP for its styling properties is likely to yield varying results depending upon local climate and individual handling of the hair once the film is dry. It seems prudent to perhaps avoid use of PVP-based gels, unless you live in a very moderate temperature and humidity zone (and you aren’t apt to handle your hair physically much once the gel is applied).
PVA (poly vinyl acetate)
PVA (poly vinyl acetate) overcomes some of the drawbacks of PVP. It is less apt to absorb moisture from the atmosphere, as it is water resistant. It is also a more flexible material, so it can bend without breakage, therefore, flaking is not an issue. However, it is not as substantive to hair as some of the other polymers (such as PVP or the polyquaterniums), and as a result curl retention or style hold is poor, and the effects wear off during the day.
Co-polymers such as PVP/VA copolymer and acrylates copolymer are designed to bring more balance to a formula. These materials have segments that are rigid and water soluble, and also have segments that are water resistant and more flexible. This creates an overall polymer that is strong, yet tough and less likely to flake. The polymer is sufficiently water soluble as to be fairly easily removed from hair, yet it is hydrophobic enough to resist absorption of moisture from the local environment.
Other polymers can also offer various advantages, such as polyquaternium (cationic) polymers, which can provide conditioning and smoothing properties, as well as good hold and humidity resistance. Polyurethanes are excellent for thermal resistance for heat styling.
Research is ongoing to find the perfect polymer or polymer system that can meet all of the requirements for a gel, but it is likely that we will always be settling for the “best fit” for the desired purpose. Besides, it would be boring (and potentially career-threatening) if we always had to choose the same polymer every time. It is fun to play with different ones and with various combinations of polymers and other additives. The educated consumer can determine which product or products is best for their hair and their environment by closely examining the ingredients list and asking questions if they find ingredients about which they are unsure. You may need one product for summer and one for winter too, depending upon where you live.