It seems that the plaster you use is never quite fast or slow enough for that project you may be working on at any given time. Well now you have CONTROL with these products. If you want to slow down the set time of your plaster (by plaster we mean any of the plasters or gypsum cements) add a little plaster retarder to your water before you add the plaster and you'll have more working time. Conversely, if you need to speed things along, add a little accelerator to your mix and hold on to your hat. Available in two pound tubs.