Head & Shoulders. Dove Body Wash. Harry’s 2-in-1. When we think of shampoos, there are several images that come to mind. What exactly is a shampoo, and what’s the science behind it’s applicability and cleansing properties? The science is simple, yet astounding.
In a previous post, I covered the basics of what goes into a quality cleanser. However, in this post, we will take a more microscopic look at what makes a cleanser work. In other words, we’ll look at the science of the components in a cleanser. Ready? Let’s go!
Water and Surfactants
The majority of most cleansers consist of water. The second most abundant substances are surfactants. Surfactant is short for surface-active agent and are are usually organic compounds that are amphiphilic, meaning they have a hydrophilic head region and a hydrophobic tail region. Furthermore, surfactants are classified according the charge of their head region: anionic, cationic, nonionic, and zwitterionic. Anionic and zwitterionic surfactants sometimes respond to sodium chloride by increasing in viscosity. Fun fact aside, this chemical dual-action property of differing water-affinity regions is the main reason for the cleansing ability of surfactants, as the hydrophilic head interfaces with the water from the faucet or shower head and the hydrophobic region interfaces with the oils in the hair and skin and on the scalp. As you massage the cleanser onto the hair or skin, the air mixed with the surfactants creates what we know as the lather. This air/surfactant matrix lifts the oils/dirt off the hair, scalp, and skin, and the water washes them away. Who knew there was so much involved in shampoo?! That’s the heavy lifting of cleansers. Although there’s still some gristle to cover, then on to the art and preservation.
Chelants
Chelating agents (chelants) bind to metal ions present on the body and in the hard water used to wash yourself. They form complexes, facilitating an overall greater cleansing experience.
Conditioning agents
There are many kinds of conditioning agents. The most traditional are silicones, compounds that have a Silicon oxygen backbone chain (Si-O-Si-O…). They coat the hair and provide luxurious effects like shine, detangling, and softness. A major downside is they tend to deposit in the hair, meaning they accumulate in the hair and follicles, damaging your hair. This fact, and that D4 and D5 tend to be bioaccumulative, have led to silicones falling out of use in personal care products. Fortunately, greener options are available. Polyquaterniums are typically synthetic or have plant material as the starting source. Polyquats have several positively charged groups (quaterniums) that attach to the hair and skin; hair and skin just happen to be slightly negative in charge. Amino acids have become popular in the last half decade. They attach to the hair and skin, binding water in the region, thus retaining moisture. Another green option are oils. They coat the hair and skin, leaving a moisturizing and soft after-feeling. Good oils for the hair and skin are Almond, Argan, Apricot, Avocado, and Jojoba.
Preservatives
Preservatives are the guard system of your product. They keep the bad microorganisms away. Newer and greener alternatives keep coming into the market, giving the pros and amateurs more options. Of course, older preservatives like Phenoxyethanol blends and organic acids (Potassium Sorbate and Sodium Benzoate) work well. Though, if you’re looking to take the natural approach, Leucidal Liquid SF, AMTicide Coconut, and Planservative. Be advised: natural preservation carries a higher price tag.
Scent
How and what you decide as your scent profile will give your product a signature property. The scent is the unique identifier and organoleptic property that any personal care product will possess. There are two general approaches: synthetic and natural. Going the synthetic route requires knowledge of perfumery, an occupational endeavor all its own. Most people go to fragrance houses like Custom Essence, Firmenich, Givaudan, and Sozio. Given some time and education, learning to make natural scents using essential oils can given your products the eco-friendly claim and personal flair. If you’re seriously interested in pursuing this option, Palette Naturals provides an accords kit and conducts a workshop that is instrumental. In any case, give your scent some lengthy consideration. It’s your personal statement coming through your product.
Adjusters
Viscosity and pH are two critical properties of any cosmetic product. pH affects efficacy of the preservative system, viscosity at times, and effect on hair and skin. Viscosity affects filling and texture. Texture is one of the first things customers evaluate about a product. Too thin of a shampoo or too thick a cream and the consumer will move on to inspect the next item on the shelf. Citric acid and sodium hydroxide are the usuals for adjusting pH. As for adjusting viscosity, sodium chloride works well for increasing viscosity in anionic and zwitterionic surfactant systems. Citric acid can help increase viscosity in some amine-based surfactant systems.
That’s a wrap. More than you anticipated, but less than you dreaded. Hopefully you learned something about products that you use everyday. Perhaps next time you pick up your favorite body wash and read the ingredients list, you’ll think of all the chemistry that went into making that product. Have a good one.
Greengen Labs 