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A loss of adhesion from concrete flooring results in flaking and peeling if the paint coating.

Inappropriate coating for the amount or type of wear and exposure the floor will receive.
Hardeners added to concrete often prevent good adhesion.
Concrete contains alkali, which is pushed to the surface as water migrates through the concrete. When the water evaporates, the alkali leaves a crystallized substance called efflorescence between the concrete and the paint that pushes against the paint film and causes peeling.
Grease, oil, wax, and dirt tend to soak in and are difficult to remove from concrete.
Moisture seeping through concrete floors in that is laid on-grade, without a moisture barrier, do not hold paint well.
If a concrete floor is old, it could crumble, taking the paint film with it.
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 the oil coating. This reaction is called specification and results in extremely poor adhesion and softness of the alkyd coating.

Concrete must be free of moisture as much as possible (moisture seldom drops below 15% in concrete). Test for moisture or dampness by taping the edges of a 2’ x 2’ plastic sheet on the bare surface (an asphalt tile or other moisture-impervious material will also do), sealing all of the edges. After 48 hours, inspect for moisture, discoloration, or condensation or the concrete or the underside of the plastic. If moisture is present, the source must be located and the cause corrected prior to painting.
Remove all surface contamination by washing with ProClean Professional Prep Wash Cleaner or other appropriate cleaner, rinse thoroughly, and allow to dry.
Scrape and sand existing peeled or checked paint to a sound surface. Sand glossy surfaces dull.
Remove all from release agents, curing compounds, salts, efflorescence, laitance, and other foreign matter by sandblasting, shot blasting, mechanical scarification, or suitable chemical means. Refer to ASTM D4260. Rinse thoroughly to achieve a final pH between 7.0 and 10.0. Allow to dry thoroughly prior to coating.
Surfaces must offer sufficient profile to achieve adequate adhesion. If the concrete feels like 120-grit sandpaper, the profile is enough for the product to bond properly with the substrate. If the surface does not have this texture, etch the surface with H&C Concrete Etching Solution first, following label directions. For very smooth surfaces (toweled concrete with no porosity), use H&C Concrete Etching Solution at full strength. For smooth-troweled concrete with some porosity, 1 part H&C Concrete Etching Solution to 2 parts water should be etched. Do not etch painted concrete does not need to be etched. Do not etch painted surfaces.
Because water will collect in low spots and deposit etching and cleaning residue, it is recommended that the floor be vacuumed to remove any remaining water.
If surface deterioration presents an unacceptably rough surface, ArmorSeal 5020 Floor Resurfacer is recommended to path and resurfaces damaged concrete. Fill all cracks, voids, and bugholes with ArmorSeal Crack Filler.

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