There are many clay masks out there, but why should you go dry clay?
When clay and other dry extracts come in contact with liquids the product becomes active. When a liquid/wet mask formula is stored in a jar it becomes less and less active over time, meaning the mask will loose its efficiency over time. However, that is not the only reason to use a dry mask.
Clay is generally a very sensitive ingredient, more so when it is wet. If wet clay is not handled with care there is a risk off cross contamination from the air or fingers. To avoid cross contamination chemicals and preservatives are used to keep the mask from moulding.
As a mask sits on your skin for a long time to penetrate your skin you should opt for something natural with out chemicals. That is why a natural dry clay mask is more beneficial for your skin. Not only is it chemical and preservative free, it will never loose it activeness over time. As clay react with liquid it becomes active, this means the mask will be as active it possible can be every use.