Plaster Mottling: What is it?
Mottling is a normal part of the plaster curing process. This occurs during the first few weeks of a new pool. Light and dark variations in whiteness or color may have the appearence of staining. Mottling is not staining it is the opposite. Calcium hydroxide is percipiated out of the plaster matrix into the pool water solution. Too much (excellorant) Calcum Hydroxide, overtrowling, and other conditons can contribute to an extreme mottling condition.