Calcium Thioglycolate trihydrate is a fine crystalline powder that is used as a depilatory agent. Calcium thioglycolate is much less irritant than potassium thioglycolate. On the other hand, it is less soluble and less effective in comparison to potassium thioglycolate. Note: 2% of Calcium Thioglycolate trihydrate corresponds to 1% of thioglycolic acid. Please observe local regulations with regards to the restricted use of thioglycolic acid.