Often times adding clays or powders to lotions may make them harder to sterilize. I suggest you sterilize the powder or pigment before adding them you formations that contain water. It is quite simple and straightforward.
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- Completely remove all moisture from the powder by putting it into an over on low heat (160 degree F).
- Bake the powder at 160 degrees F for at least one hour. Decant into an sterile container till ready to use.