All of the following statements are true about a chemical depilatory EXCEPT:

A chemical depilatory is designed to dissolve hair above the skin's surface, not to target the papilla, which is located below the surface in the hair follicle. The primary action of a chemical depilatory involves breaking down the protein structure of the hair, typically using active ingredients such as calcium thioglycolate or sodium thioglycolate that can effectively degrade keratin. This makes hair removal effective but does not involve the decomposing of the papilla itself.

The other statements are true: regrowth indeed occurs within several days as the hair follicle remains intact, conducting a patch test before application is recommended to check for allergic reactions or sensitivities, and thioglycolic acid derivatives are widely used in these depilatories as their primary active components.