Extratime is a chemical additive for use with finishing plasters. The additive slows the curing process of the plaster by slowing the chemical crystal formation that causes the gypsum plaster to set or harden. Extratime is recommended for moderate lenthening of finishing plaster setting times. Extratime will lengthen the setting time by 30-60 minutes depending on the ambient temperature, relative humidity of the environment and the surface being plastered.