In this question, Newbie Tuesday: Turning your cleanser into an exfoliating cleanser, Jessica asks: I am actually working on something at home and I have pink french clay and I want to make some sort of scrub for the face. Most of the websites that I can buy the clay from just suggest mixing with water and adding to the face but i would like to add more than just water to my product. I was wondering if I could add essential oil or some hydrolyzed proteins or some tea tree oil.

Clay is incredibly hard to preserve, so it's always best to make a clay mask just before using it by adding it to a small bit of lotion or a toner or something similar. In my recent botanical extract (part one) e-zine, I made a bunch of these by creating the clay portion, then adding a gel or toner to it before applying to my face. Add your hydrolyzed proteins, hydrosols, and other water soluble ingredients to the toner or gel, and add powdered botanicals to the dry clay mask portion.
If you want to add clay to a product that you'll preserve, please use a really strong, broad spectrum preservative designed for hard to preserve products, like Phenonip or Germaben II at 1%, and only keep it for a week or so. After that, you're asking for contamination.

As a note, this is red reef clay from Windy Point Soap in Alberta. It's a type of kaolin clay. It's an awesome burgundy colour, but note that a little goes a long way. Make sure you do a patch test before doing a full, thick facial mask. 

As an a...