Marcelle Hydrating Cream Cleanser Versus Stratia Velvet Cleansing Milk

Your skin makes glycerin on its own (mostly from sebaceous oil breakdown) and shuttles it to your outermost layer of skin, or your epidermis, via aquaporin-3.

Aquaporin-3 is a transporter that is essential for normal skin hydration, elasticity, and repair. Interestingly, mice lacking in AQP3 have dry and less elastic skin that can be fully corrected with glycerin.

This ingredient is non-irritating, plays well with almost every ingredient, and works across all skin types. Typical use is anywhere between 3-10% but can go up to 79% in some leave-on products.

Just know very high concentrations (>40%) can feel tacky in low humidity.

Glycerin is the name for this ingredient in American English. British English uses Glycerol/Glycerine.

Once inside a formula, it turns into sorbic acid, which does the actual preserving. It works best in slightly acidic products and isn't great against bacteria alone so you'll usually see it teamed up with other preservatives like Sodium Benzoate.

Typical use at around 1% or less, and the EU caps it at 0.6 percent. The Cosmetic Ingredient Review Panel has concluded it's safe as used in cosmetics and it's also a common food preservative.

Potassium sorbate has a pretty good safety record on skin. Formulas with up to 0.5% were not irritating or sensitizing in human testing, and true allergies are rare.

Irritation or sensitization can happen mostly with medicated creams used on broken skin.

Definitely avoid Potassium Sorbate if you're allergic to Sorbic Acid, since they're essentially the same thing on skin.

There is a known harmless and short-lived reaction where some people may notice brief redness or itching right after applying. Just know this is common and not a sign of allergy.

You'll also recognize water as that liquid we all need to stay alive. If you see this, drink a glass of water. Remember to stay hydrated!