This is a additive to pre-mixed gypsum mud.

This product was designed to work with most any pre-mixed gypsum mud. 
We reccommend all U.S.G. Products since most testing has been with their products.

By adding  three capfuls of 100mph mud to a regular mud pan (5Lbs) and folding in the set time is about 30 minutes in normal temp. 

For a hot patch a five inch knifefull of gypsum mud with 2 caps of 100mph mud will set in about 12 minutes. 
There are contractor packages to mix 1/2 a five gallon bucket for a 40 minute set.