Saturday, September 10, 2016

Newbie Tuesday: Facial cleansers - what are surfactants?

On Tuesday, I asked you to think about your skin type. Today I'll share with you what I know and love about foamy, bubbly, and lathery surfactants.

I love surfactants the way other women love shoes. I have a closet of them, and sometimes I take them out of their little box in my workshop and look at them, enjoying their viscosity, clarity, and scent. I don't know what you may have heard from Janice in accounting, but I didn't create my own "surfactant a day" calendar to hang in my office. And I definitely don't hug them when no one's watching! You don't have to love them as much as I do, but I encourage you to at least like them a bit.

Surfactants (surface active agents) are ingredients that lower the surface tension of a liquid and lower the interfacial tension between two liquids. Surfactants make it possible to mix oil and water together in something like a lotion or remove oil, dirt, and soils. This means emulsifiers, like Polawax and e-wax; solubilizers, like polysorbate 80 and PEG-40 hydrogenated castor oil; and detergents are all surfactants.

I'll be using the word "surfactant" to refer to our lathery, bubbly, and foamy surfactants. They're also known as detergents, but people really don't like that word for some reason. 

Surfactants have a hydrophilic (or water-loving) head and a lipophilic (or fat-loving) tail. The hydrophilic head clings onto watery stuff - say the water phase of our lotion - and the lipophilic tail creates a ball around the oily stuff - the oil phase of our lotion.

Oil, sebum, and soil are hydrophobic or water hating, so they repel water. (This is why water alone can't wash your clothes!) Surfactants in soap break the surface tension of the water making it easier for those water molecules to get to the things we want removed. They disperse the water-hating molecules into a suspension, which is then rinsed away leaving your skin, hair, clothes, and everything else sparkling clean!

When it comes to making facial cleansers with surfactants, our goal is to create a product that will gently disperse sebum, oils, dirt, pollution, make-up, and other water repelling ingredients to be rinsed away, leaving our skin feeling fresh and clean. We don't want it to be so harsh that it strips our skin of all its oils, but we don't want it to be so mild that it leaves behind things we want removed.

With all of this in mind, join me tomorrow as we take a closer look at the pH of our surfactants.

2 comments:

Katrīna Orešonoka said...

For cleaning face I use soap nuts (I boil 20 nuts in 300 ml water) and add 5% decyl glucoside, which is very mild surfactant. The same liquid I use as shampoo, and my hair and face like this very much! I can recommend very good natural thickener for surfactant liquids like facial cleaner, shampoo, shower gel. Before I used xanthan gum, guar gum, which left on my skin and hair thin layer, so my hair looked dirty after washing. Xanthan and guar also decreased foaming properties, so final product felt mucous. I discovered CARRAGEENAN! Carrageenan is also natural, extracted from seaweeds. And it increase foaming properties! As a bonus, it increase hair volume if it is in shampoo. It cant explain why it happens, it is from my experience.

Arismac said...

Very much looking forward to Tuesday, Susan. I am trying yo make a body wash lotion with a pH of between 5.5 - 6.5. May I add ammonium lauryl sulphate to your "Facial Lotion Bar" receipe (Page 29 "Back to Basics" by Susan Barclay Nichols) in order to nudge the pH down while still getting a nice foamy lather? The lotion bar is aimed for use by older people who like me have spent a lot of years under and Australian sun.