Floor coating failures rarely come from the coating. They come from what was underneath it: a weak surface layer, trapped moisture, or contamination that was painted over. Preparation is not a preliminary to the job, it is the job.
Moisture is the first question
Concrete slabs release moisture for months after pouring, and slabs without an effective damp proof membrane release it indefinitely from the ground. Coating over a wet slab traps that vapour, which builds pressure under the film and lifts it as blisters or delaminated patches.
Test rather than assume. Relative humidity probes cast into drilled holes give the most reliable picture of internal slab condition; surface based methods give a quicker but less complete answer. A slab that fails the coating manufacturer moisture limit needs either more drying time or a moisture tolerant primer system designed for the condition.
Removing laitance and gaining profile
The top layer of a power floated slab is laitance: fine, weak material that looks dense but has little strength. Coating bonded to laitance is bonded to something that will detach under load. Mechanical preparation removes it and creates profile. Shot blasting is the standard for large warehouse areas, diamond grinding suits smaller areas and edges, and acid etching is generally a poor substitute because it neither removes laitance reliably nor produces a consistent profile.
Contamination in service areas
Existing floors in workshops and plant rooms carry oil and grease that has penetrated the surface. Degreasing before mechanical preparation matters, because grinding oily concrete drives contamination deeper. On heavily contaminated slabs, localised removal of the affected concrete is sometimes the only reliable route.
Joints, cracks and detailing
Moving joints must be honoured through the coating, not bridged, or the coating will crack along them anyway in a less controlled fashion. Static cracks are opened out and filled with a suitable resin. Coving at wall junctions is specified in hygiene areas and needs planning before the floor coating starts.
Environment during application
The same dew point and temperature discipline applies as for steel, covered in our summer application guide. Slabs cooled overnight in an air conditioned warehouse can sit close to the dew point of incoming humid air, so measurement at the slab surface matters.
MENA Industrial Supplies supplies epoxy floor systems and primers with data sheets stating moisture limits and preparation requirements.