A loss of adhesion from
concrete flooring resulting in flaking and peeling of the paint coating.
• Hardeners added to
concrete often will prevent good adhesion.
• Concrete contains alkali which are drawn to the surface by water and
deposited there. When the water evaporates, the alkali leaves a crystallized
substance called efflorescence which pushes against the paint film and
• An additional problem with concrete is that grease, oil, wax and dirt tend
to soak in and are difficult to remove resulting in peeling.
• Moisture seeping through concrete floors in basements contributes to
peeling paint, and floors that are laid on-grade, without a moisture
barrier, do not hold paint well.
• If a concrete floor is old, it could crumble, bringing the paint film with
• Peeling from concrete also can occur when an oil based floor finish is
applied to a bare, unetched, uncured concrete floor. When oil resins
contained in the floor coating come in contact with the alkaline concrete
surface, they combine, react with one another, and form a soap film between
the concrete surface and the oil coating . This reaction is called
saponification and results in extremely poor adhesion and softness of the
• Some concrete floors are
unsuitable for painting due to moisture or hardness. To test for moisture,
tape an 8" x 8" piece of plastic to the floor around all edges. If after 24
hours there is moisture under the plastic or the concrete changes color, it
is not paintable. Hardness can be tested by dropping water on the concrete.
If the water spreads and darkens the concrete, the surface should accept
• First, remove the loose paint by scraping and, if necessary, use chemical
strippers. To clean the floor, scrub with hot water and a strong detergent
solution. Avoid mild dishwashing detergents; they contain skin softening
ingredients which interfere with paint adhesion. Rinse thoroughly. Allow the
surface to dry for several days. Stubborn grease may continue to rise to the
surface; and in that case, you may have to scrub again.
• Bare concrete must be etched with a 10 percent solution of muriatic acid
and water. Follow all label instructions when using this product. When p a i
n t i n g with a latex coating, use a 10 percent solution of phosphoric acid
instead of muriatic. When the floor is properly etched, it should resemble
the texture of fine sandpaper. If the concrete is loose, sand off any
crumbly are as.
2 Coats of FLEX BON #680 Series Interior-Exterior
Acrylic Concrete Stain