Surfactants and Cleansing Products

By: Eric Abrutyn, TPC2 Advisors Ltd., Inc.

Posted: June 30, 2009, from the July 2009 issue of Cosmetics & Toiletries.

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Incorporating a surfactant system is one of the first steps to making a cleansing product. Minimal issues arise when incorporating sodium or ammonium lauryl sulfate since the surfactant is provided in a relatively dilute solution (28–30%). Using sodium laureth sulfate (SLES) instead presents added challenges since SLES typically is provided in a concentrated solution of 70%, and acts more like a gel than a solution. Therefore, formulators should consider how to incorporate SLES into a formula. Following are some tips, provided by Barry Salka of Surfactants Inc., to incorporating SLES so as to minimize process issues. It should be noted that these suggestions can be combined to facilitate faster processing with good solubilization of the surfactants:

1. If NaCl will be added to the formula, add it directly to the SLES. For example, if the formula contains 20% SLES and 0.5% NaCl, add the 0.5% NaCl directly to the SLES so that it represents a high salt concentration in the SLES and helps to break up the concentrated SLES gel; then add the NaCl/SLES to the water and follow with the remaining ingredients.
2. Consider adding other surfactants to the water first to create co-micellae; then add the SLES so the gel breaks up easier.
3. Warm the water and SLES first to around 35–45˚C each, then add the SLES to the water phase.
4. If using a rheology modifier, consider incorporating a portion of the water into it as a separate phase, then adding this mixture to the solubilized surfactant system-water phase. Chelators, antioxidants and preservatives can be added to this mixture before neutralization. It is better to neutralize/pH-adjust the formula after most of the ingredients are incorporated to facilitate easier processing—before the system builds too much rheology.

Outlook on Cleansing Materials
As noted, the growing trend in the marketplace is focused on natural ingredients and parallel to this is a push for eliminating marketing references to chemical preservatives, as well as anything to do with sulfates or synthetic surfactants. With this trend, biosurfactants have emerged as a new category of products since these materials are created via fermentation processes incorporating enzymes and bacteria. They behave much like synthetic surfactants and are available in a variety of ingredient classifications. However, biosurfactants tend to provide lower process yields than conventional synthetic processes and thus cost more. In addition, they can contain higher levels of impurities or remnants of the bacteria used to manufacture them.

The movement for nature-derived surfactants also is generating cost issues for manufacturers, retailers and consumers. These surfactants, like biosurfactants, are based on natural starting materials but have been modified. Again, these materials are more costly than non-naturally derived synthetic surfactants but as more of these materials are used, it is possible that their costs will be driven down.

References
Send e-mail to tpc2advisors@yahoo.com.
1. Harry’s Cosmeticology, 8th ed., M Rieger, ed, Chemical Publishing: New York (2000), 187– 211; 485–501
2. The Chemistry and Manufacture of Cosmetics: Vol I—Formulating, M Schlossman ed, Allured Business Media: Carol Stream, IL (2006)