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.
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.