Cure and Seal and Curing Problems, and How to Fix Them
Many cure and seal problems trace back to over-application: a coat that is too heavy, or too many coats. Start with the symptom you see; each guide gives the likely cause and the fix.
Guides in this section
-
Cure and seal turned white
Why sealer blushes white and how to clear it.
-
Peeling, flaking or blotchy
Over-application, moisture and how to repair the finish.
-
Dusting, crazing and curling
Surface defects caused by poor curing and how to stop them.
Find your problem by symptom
| What you see | Likely cause | First fix to try | Full guide |
|---|---|---|---|
| Milky white haze on sealed concrete | Moisture trapped in or under the film (blush) | Solvent-based acrylic: xylene can re-melt it. Water-based: usually strip and redo | Cure and seal turned white |
| Sealer peeling or flaking off | Too heavy a coat, too many coats, or a dirty or damp surface | Remove loose film, clean, recoat thin | Peeling, flaking or blotchy |
| Blotchy, uneven or shiny patches | Uneven spraying or puddling | Even out with a thin coat, or strip if heavy | Peeling, flaking or blotchy |
| Yellow or discolored surface | Resin compound over-applied | Let it weather or remove it | Peeling, flaking or blotchy |
| Surface powders under traffic | Weak top layer from bleed water, late or no curing | Remove the weak layer, then harden or coat | Dusting, crazing and curling |
| Web of fine surface cracks | Crazing from fast surface drying | Usually cosmetic; seal to hide dirt lines | Dusting, crazing and curling |
| Flooring or tile not bonding | Curing compound film still on the slab | Test, then remove the film | Test for curing compound |
Why over-application causes most of them
A heavier coat looks like extra protection, but cure and seal is designed to go on thin. At typical solids it dries to roughly a mil or so of film. Pile on more and the film traps moisture, stays soft, fails to bond to the concrete under it, and later turns white or lets go. Resin curing compounds can also yellow when applied too heavy.
The fix starts before the problem: spray at the data sheet rate, use two light passes instead of one heavy one, and do not add coats the product does not call for. The coverage calculator shows how much a slab should actually take.
Before you fix anything
- Find out what is on the slab. Solvent and water-based sealers need different fixes. Check the pail, the receipt or ask whoever applied it.
- Try the water drop test. A drop that soaks in within about 5 to 10 seconds suggests there is no film. One that beads means something is still there.
- Test a small area first. Any solvent, stripper or recoat should go on a test patch before the whole slab.