The Science Behind Mild Technology – Part 1

While surfactant-based skin cleansers work to remove dirt, oil, sweat, odor and other unwanted substances from the skin, they might also inadvertently remove beneficial natural compounds from the skin’s surface. If too many of these natural compounds are removed and not recovered by skin rejuvenation or replaced by lotions, creams or other means, the skin’s barrier becomes weak and damaged, which can result in dryness, itchiness, irritation and even premature aging.

Luckily, Lubrizol scientists employ an array of rigorous test methods to ensure cleansing formulations and their ingredients are soft on skin tissue. In the first half of this blog post, we’ll discuss three in vitro test methods Lubrizol uses. In the second half, we’ll explore ex vivo and in vivo tests, and what goes into formulating a mild cleanser.

Zein Test

Zein, a yellow corn protein that closely resembles the keratin present in skin, is the star of the show in this test. This method determines the likelihood of a surfactant solution to damage skin protein by measuring the amount of zein the solution can dissolve. The more zein dissolved, the higher the solution’s skin irritation potential and the lower its mildness. Zein protein is measured using BCA assay with UV/Vis spectrometer.

The Zein Test is particularly useful because it’s fast and suitable for studying both individual ingredients and full formulas.

Lipids Extraction Test

Subcutaneous lipids are important natural compounds that surfactants may inadvertently remove when cleansing the skin. Removal of these compounds damages the skin’s lipid barrier, which can result in dryness and irritation.

As a major component of subcutaneous lipids, fatty acids are especially vulnerable to being removed by cleansers. To measure a cleanser’s potential to remove fatty acids from the skin, scientists use the Lipids Extraction Test. During this test, a pre-measured amount of stearic acid is added to the surfactant solution. The more stearic acid that is dissolved, the higher the solution’s potential for skin lipid barrier damage.

HET-CAM Test

The Hen’s Egg Test-ChorioAllentoic Membrane (HET-CAM) serves as an alternative eye and vaginal irritation study to replace animal testing. The test models the potential effects of a surfactant solution on the conjunctival tissues of human eyes and vaginal tissue by observing how the vasculature of a fertilized chicken egg responds to a small drop of the solution. The more quickly hemorrhaging, vascular lysis, and coagulation occur, the higher the irritation score of the solution.

Summary

Protein and lipid damage, along with eye irritancy, must all be considered when developing mild and moisturizing formulas. Lubrizol uses robust in vitro tests to ensure the mildness of our ingredients and cleansing formulas.