What Is Cosmetic Formulation? Part 2: Surfactants

In technical terms, a surfactant is a compound that lowers the surface tension between water and other substances.  They’re very effective cleansers, lifting dirt and oils from surfaces and keeping them separate so they can be rinsed away.  Soap made from vegetable or animal fats mixed with an alkali substance has been used since at least 2800BCE and is the earliest known surfactant.

In the 20th century soap shortages during and after World War II lead to the development of synthetic surfactants, often called detergents.  Many of the modern products we think of as bar soaps (for example, Dove and Olay) are synthetic detergent (syndet) bars.  Others, such as Irish Spring and Ivory, are made from rendered animal fat (tallow).

In the world of handcrafted soap a distinction is often made between “true” soap, made with animal or vegetables fats and lye, and synthetic detergent bars.  Both will get you clean, so how should you choose what to use?  Here are a few things to consider` …

Synthetic surfactants are typically much more effective cleansers than soap.  When it comes to bars you use in the shower you probably won’t notice any difference.  In your washing machine, though, the difference is huge.  Before the development of synthetic surfactants getting clothes clean with soap and water involved using a washboard or some other means to mechanically remove dirt and oil.

Soap is the result of an interaction (saponification) between oils and/or fats and an alkali substance, like lye.  While no lye remains in soap after saponification takes place, the pH of the finished product is very high (alkaline).  This is always true, because lowering the pH results in the breakdown of the soap.  While most people readily tolerate the high pH on their skin, those with very sensitive skin or special conditions might consider trying a pH-balanced syndet bar.

Finally, if you practice a vegan or vegetarian lifestyle, many mainstream bar soaps include tallow, which is produced by rendering animal fat.  Most synthetic surfactants are derived from plants, although it is always worth checking the source of all ingredients.

Watery Mountain Essentials bar soaps are true soap, made from non-GMO plant oils and lye with added skin-friendly ingredients.  Except for those that contain goat milk or honey they’re vegan friendly and never tested on animals.  We’ve aim for the best of all worlds in our bar soaps, blending age-old soap-making traditions and modern considerations about animal welfare and a healthy planet!

Watch for more information about synthetic surfactants in the next post …


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