Rough or Gritty Topcoat

Use a hand and then a blade, in that order, and the answer usually arrives in seconds.

Run a gloved hand across the floor first to find the worst area, because this defect is nearly always felt before it is seen. Then take a blade or a plastic scraper to a small patch.

Grit that scrapes off and leaves gloss behind was lying on the surface. Something landed on the coat after it had gone off, or the coat was already skinned when it landed. That is the easiest of the three.

Grit that will not move is cured into the film, which means it was in the material or landed while the coat was still open. Roughness with nothing to scrape at all, that follows the pattern of the flake or the grinding marks underneath, was never buried in the first place, and that is a film build problem rather than a contamination one.

No, and they are worth separating because the mechanism is opposite.

A fisheye is the coating pulling AWAY from something it cannot wet. You get a circular bare or thinned spot with a raised rim, and the defect is an absence of coating at that point. The contamination is usually oil, silicone or a release agent, and it repeats in the same places if you recoat over it.

This page is the reverse: particles PRESENT in or on a film that is otherwise continuous and sound. Nothing pulled back, nothing is bare, and the surface is simply not smooth.

The two can occur on the same floor because both come from a dirty environment, so it is worth checking for both rather than assuming the first one you find explains everything.

Almost always from the air rather than from the floor, and it keeps arriving for hours after anybody stopped making it.

Grinding anywhere in the building is the usual source. Fine dust stays airborne long after the machine is switched off and settles gradually onto whatever is below it, so a bay coated in the afternoon collects the morning's preparation. Cutting, sweeping and moving materials do the same.

After that: forced air heating and fans blowing across the floor rather than above it, open doors on a windy or dusty site, insulation and ceiling debris disturbed by anybody working overhead, and clothing, particularly anything fleecy.

The practical point is that a room that looks clean and a room that is clean to coat in are different standards. If dust was generated anywhere in the space that day, assume it is still coming down.

Yes, and it is under-suspected because people trust a sealed tin.

The usual sources are partly gelled material scraped from the sides of a mixing bucket, resin that has been over-mixed or left too long so it has begun to set before it reached the floor, a roller sleeve shedding fibre or carrying dried material from a previous job, and pigment or filler that has settled hard in storage and was not properly re-dispersed.

Cold material makes several of these worse, because a more viscous mix is harder to get uniform and less willing to release what is in it.

The cheap protections are to mix into a clean bucket, never to scrape the sides into the pour, to use fresh sleeves for a clear topcoat, and to strain the material if there is any doubt at all. Straining a topcoat costs a minute and removes an entire category of this defect.

That is the third branch, and it is the one people miss: the topcoat never buried what it went over.

On a flake floor the base coat is broadcast to refusal, so the surface it leaves is a bed of chip edges standing proud. Those are normally scraped back and then buried by the clear coats. If the floor was not scraped, or the topcoat was spread too far to have enough material to level over the edges, you feel the flake through the finish and there is nothing to scrape off because nothing landed on it.

The same applies over a heavily ground slab. A coarse profile takes material to fill, and a film laid thin enough will follow the profile rather than level over it.

The tell is that the roughness has a pattern that matches what is underneath, rather than being random specks. If you can see chip edges or grinding marks lining up with what you feel, this is the branch you are in.

Check before treating it as a fault, because this is the one version of a rough floor that may be correct.

Anti-slip additives are deliberately broadcast into or mixed through a topcoat to give texture underfoot, and a floor specified with one is meant to feel rough. Whether the amount is right is a separate question from whether it is a defect.

What does go wrong is dosage and distribution. Too much additive, or additive thrown unevenly, gives a floor that is aggressive in places and smooth in others, which is both unpleasant and a genuine slip inconsistency. That is a legitimate complaint, but it is a different conversation from contamination and has a different fix.

So before anybody quotes a repair, confirm what was specified. A floor that is doing what the specification asked for is not this page.

It depends entirely on which of the three branches you are in, which is why the test comes first.

Surface grit that scrapes off can often be handled without recoating. Screen the floor lightly, clean it thoroughly, and in many cases the gloss and the feel both come back. If the specks left marks in the film when they were removed, it needs a coat.

Grit cured into the film has to be abraded flat and buried. Screen or lightly abrade the whole floor to a uniform dull finish, vacuum and tack it, then apply a full topcoat. Spot work does not blend on a gloss finish.

A topcoat too thin to bury what is underneath needs material rather than abrasion. Scrape or abrade the proud edges, then apply another full coat at the correct spread rate. Abrading alone here just removes what little film there was.

In all three cases the recoat is the whole floor, not the affected part. A patch on a clear coat reads as clearly as the defect did.