Definition - What does Saponification mean?
Saponification is a potential problem after applying paint or a coating to concrete or another surface. If saponification occurs, then the adhesive strength of the coating can suffer; over time the coating chips off, exposing the inner surface to the corrosive environment.
Saponification is a process that produces soap from the alkaline hydrolysis of fats and lye.
Corrosionpedia explains Saponification
When saponification occurs, the coating material's resin is broken down by the alkali and moisture on the surface, and the coating becomes sticky and often discolored. This problem usually occurs when a coating is applied directly to a concrete or metal surface that has not fully cured. The end result is total loss of adhesion and a terrible sticky mess.
Care must be taken when preparing the surface to avoid saponification. Surface preparation is a critical factor influencing the coating's service life.