Loss of adhesion of the
paint film exposing the underlying brick or masonry surface.
The most common cause of
peeling from surfaces composed of mortar, stucco, brick, building block or
concrete is efflorescence. Soluble salts are contained in these materials.
When dissolved by water, they will be carried to the surface and will remain
there after the water has evaporated. These crystallized salts push the
paint away from the surface, and peeling results.
Sometimes efflorescence occurs on brick walls of new construction. A common
building practice is to wash new brick or concrete walls with muriatic acid
to clean away excess mortar. If the final rinsing was not thorough and the
wall was later painted, any salts left on the bricks absorbed the moisture,
causing peeling. (Current thinking is that acid etching, especially with
muriatic acid, actually adds chloride salts back into concrete, so itís best
to avoid acid etching).
Not all peeling from masonry is caused by efflorescence. Peeling can occur
when any paint is applied over an uncured surface with a high alkalinity
content (for example, unetched concrete).
If efflorescence is evident,
it must be removed before repainting. First, remove all flaking or chalking
paint from the damaged area by wire brushing or high-pressure water washing.
Fill all cracks with Flex Bon patching compound or
caulking compound If the surface is very porous, apply an alkali-resistant
primer or block filler. Topcoat with an alkali resistant exterior latex
FLEX BON Knife Grade
Elastomeric Patching Compound
1 Coat of
FLEX BON #194 Series Exterior 100%
Acrylic Latex Primer
2 Coats of Top Quality FLEX BON Exterior