Does Sodium Hydroxide in Face Wash Make it Slimy?

Gemma speculates: I was wondering if sodium hydroxide was added to face washes for the purpose of pH adjustment only? I am a lab technician and have noticed the very ’slimy’ feel that solutions containing sodium hydroxide tend to adopt. I have also noticed that some
face washes containing the ingredient have the same slimy feel to them which customers could easily mistake for a ‘moisturizing effect’. Is it the sodium hydroxide that causes this consistency and what effect does the ingredient have on the skin? Can it dry the skin?

Right Brain Steps In:

It’s nice to hear from our lab technicians out there.  You do great work and are responsible for keeping this industry moving ahead.  A little known fact about the world of science, lab techs do the work, scientists get all the glory.  It hardly seems fair.

Sodium Hydroxide Slime

Your observations about sodium hydroxide on your skin are correct.  It does feel slimy.  However, we don’t recommend you touch it too often.  Dilute solutions can burn skin and concentrated Sodium hydroxide can be nasty stuff.

The reason sodium hydroxide feels slimy is because it is chemically reacting with the fatty acid esters and oils naturally found in your skin.  Essentially, you’re turning bits of your skin into soap.  (The reaction is called saponification).  And as you know, soap is slippery.

But what happens to sodium hydroxide in a face wash?

Facial Wash ingredients

To understand this, it is helpful to examine the ingredients in a face wash.  This Clarisonic face wash provides a good example.  The ingredient list is below.

Clarisonic Refreshing Gel Cleanser

Water, Sodium Laureth Sulfate, Cocamidopropyl Betaine, Cocamide DEA, Acrylates C10-30 Alkyl Acrylate Crosspolymer, Salix Alba Bark Extract (Willow), Aloe Barbadensis Leaf Gel (Aloe Vera), Vitis Vinifera Seed Extract (Grape), Camellia Oleifera Leaf Extract (Green Tea), Chamomilla Recutita Flower Extract (Matricaria), Camellia Sinensis Leaf Extract (White Tea), Laminaria Digitata Extract (Algae), Saccharomyces Cerevisiae Extract (Yeast), Arctostaphylos UVA Ursi Leaf Extract (Bearberry), Panthenol (as Vitamin B5), Cyanocobalamin (as Vitamin B12), Ubiquinone, Caprylic/Capric Triglycerides, PEG 12 Glyceryl Distearate, Sodium Hydroxide, Glucosamine HCl, Glycerin, Urea, Phenoxyethanol, Caprylyl Glycol, Ethylhexyl Glycerin, Hexylene Glycol, Fragrance

First, let’s strip away all the ingredients that are just “filler” or put in to support the marketing story.

Water, Sodium Laureth Sulfate, Cocamidopropyl Betaine, Cocamide DEA, Acrylates C10-30 Alkyl Acrylate Crosspolymer, Caprylic/Capric Triglycerides, PEG 12 Glyceryl Distearate, Sodium Hydroxide, Glycerin, Urea, Phenoxyethanol, Caprylyl Glycol, Ethylhexyl Glycerin, Hexylene Glycol, Fragrance

We’re left with

1. Detergents that actually clean the skin
2. Thickening polymers that make it gel
3. Moisturizing ingredients that reduce harshness of the detergents
4. Solvents that dilute the ingredients to make them usable
5. Fragrance to make it smell pretty
6. Preservatives to keep it fresh
7. Adjustment agents to optimize performance.

Sodium Hydroxide falls in the Adjustment Agent category. You see, when dispersed in water the thickening polymer is thin and has low pH somewhere around 2.5 – 3.5.  It only gets thick at a higher pH, say around 5-7.  The detergents help increase the pH, but you often need just a little extra boost to get the right thickness.  This boost comes from sodium hydroxide.

Fortunately, only a small amount is need to increase the pH.  That’s why there isn’t enough of it in this Clarisonic wash to react with your skin and make it feel slimy.

The Beauty Brains Bottom line

A solution of Sodium Hydroxide does have the effect of making your skin feel slippery.  However, in a face wash only a small amount is used and it is tied up with other ingredients so it doesn’t react with skin.