Fritz-Pak 95450 Plaster Delayed Set Admixture. Plaster Delay-Set is a dry powdered admixture packaged in a patented, ready-to-use, water soluble bag. Plaster Delay-Set is designed to slow down the set of plaster. It is invaluable in hot weather or when you have a shortage of workers, when you often need more time to work the plaster before it sets. It will not discolor or affect final strength of the plaster, it is very predictable in its use and will not weaken the final strength of the plaster.