Flush surface with water and dry completely. The floor should now be ready to paint. A common cause of peeling on surfaces composed of mortar, brick, building block or concrete is efflorescence, where soluble salts are present. When dissolved by water, they are carried to the surface and remain afer the water has evaporated. These salts can push paint away from the surface and peeling results.
Efflorescence occurs on brick walls of new construction.
A common building practice is to treat new brick or concrete with muriatic acid, rinsing with water to clean away excess mortar. Rinsing removes only those salts on or near the surface. After painting, salts remaining within the bricks will absorb the moisture and travel to the surface, causing peeling. Peeling can also occur when alkyd or oil paint is applied over unetched concrete. Alkyd resins that come in contact with a alkaline surface form a soap film between the concrete surface and the coating, called saponification.