Identify Your Coating Defect
You do not need to know what it is called to find it here. Start with what the floor actually looks like, narrow it with one physical test, and land on the page that explains the cause and the repair.
Work from the floor, not from a word. Find the group below that matches what you can see, read the one line that separates its members from each other, then run the test in that line if looking is not enough. If you already know what the defect is called, the troubleshooting index lists every page by name and will be quicker.
Two rules that settle most of it
Before the groups, the two observations that do the most diagnostic work. Both come from watching what a defect does rather than what it looks like, and between them they separate causes that look identical on a cured floor.
Gas moves. Contamination repeats.
- Recoat a small test patch and watch where the marks land
- New marks somewhere else: a gas defect. That air or vapor has already escaped, so the second coat gasses from wherever the slab is releasing next
- Same marks in the same spots: contamination. It is still sitting on the slab, and no number of extra coats will bury it
- This one test separates a moisture problem from a cleaning problem, and they have nothing in common except the shape they leave
For round marks, look at the middle
- There are only three possibilities, and each points somewhere different
- Closed dome: gas still trapped under an unbroken film
- Open puncture: the gas got out and the film was too stiff to close behind it
- Coating pulled back: nothing was punctured. The resin met a spot it could not wet
Match the floor to a group
Each group opens with the question it answers. Work down until one of them describes your floor, then use the tell to pick between that group's members.
Round marks in the film
Are there round marks in the coating, raised, open or bare?
All three start as gas or a spot of dirt. What separates them is whether the mark is a closed dome, an open hole, or a place the coating pulled away from.
Raised round domes in the film, from pinprick size up to a coin, sometimes in drifts across one bay and sometimes over the whole floor.
- The tell: The dome is closed. Press it and it gives, because the gas is still trapped under a film that never opened.
- Confirm it: Puncture one with a blade. If air escapes from a film that was intact until you cut it, it is a bubble and not a pinhole.
Small open holes through an otherwise flat film, closer to the surface of a cracker than to a blister. Easiest to see with a light held low and raked across the floor.
- The tell: The mark is an open puncture with coating right up to its edge. The gas got out, and the film was too stiff or too thin to close behind it.
- Confirm it: Draw a fingernail across one. A pinhole catches as a pit in a level film, where a bubble stands proud of it.
Circular bare or thinned spots with a raised rim, as though the coating was pushed away from a point. Usually visible within minutes of laying the coat, long before it gels.
- The tell: Nothing punctured the film. The coating pulled back from a spot it could not wet, so the centre is thin or bare rather than holed.
- Confirm it: Recoat a test patch. Contamination repeats in the same spots because it is still on the slab, where a gas defect moves, because that air has already gone.
The colour or clarity is wrong
Is the film sound but the wrong colour, cloudy, hazy or ambered?
The film is intact and stuck down. What separates these is whether the colour changed after cure or the surface never went clear in the first place.
A cloudy, milky or greasy film lying on the surface, often worse near doorways, cold walls and anywhere the air was damp while the floor cured.
- The tell: The haze sits on the film rather than in it. Scratch a corner and the coating underneath is sound and the colour it should be.
- Confirm it: Wash a test patch with warm water and a scrub pad. Amine blush is water soluble and lifts, where a defect cured into the film does not.
An amber or yellow cast across a floor that went down clear or white, usually strongest wherever daylight lands longest.
- The tell: The colour shifted after the floor cured, and it maps to light. Shadowed edges and covered areas stay closer to the original shade.
- Confirm it: Move a mat or a rack that has sat in place for weeks. A sharp line at its edge is UV; an even shift across the whole floor is not.
The coating is coming off
Is the coating lifting, flaking or peeling away from what it was laid on?
What separates these is what the underside brings with it: bare slab means the bond to the concrete failed, coating means one coat let go of another.
Coating lifting, flaking or coming away in sheets, sometimes releasing across a whole bay once a scraper gets under an edge.
- The tell: Lift a flake and read its underside. Bare concrete or loose dust means the bond to the slab never formed, which puts the cause in the prep.
- Confirm it: Score a small square through to the concrete and lift a corner. Clean release off the slab is a prep failure, not a coating failure.
It never hardened properly
Is the floor still soft, tacky or printing under a boot long after it should have set?
What separates these is whether the material is uniformly soft or soft in patches, which points at the ratio or at the mixing.
A floor still soft, gummy, rubbery or taking a fingerprint long after the data sheet said it would be walkable, sometimes with a greasy or wet feel that never dries.
- The tell: Uniformly soft across the whole pour points at the ratio. Soft in streaks, swirls or patches with hard material between them points at the mixing.
- Confirm it: Press a thumbnail into an out of the way spot. Material that dents and stays dented has not cured. Material that is only tacky on top but hard underneath is a surface problem, so read the blushing page instead.
Before you repair anything, write down the conditions
Most coating failures are conditions failures, and the conditions are the one piece of evidence that disappears completely if nobody notes them. A data sheet states limits for temperature, humidity and the recoat window, and a floor cannot be checked against those limits from memory. Record the date and time of the coat, the air and slab temperature, the relative humidity, the product and batch, the mix ratio and pot life, and how long the coat sat before the next one went on. Photograph the defect with something in frame for scale.
Where more than one defect is present, and that is common rather than unusual, work in order of what has to be fixed first. Anything to do with the slab, meaning moisture, contamination and preparation, comes before anything to do with the film. A perfect topcoat over an unresolved slab problem fails again on the same schedule the first one did.
Frequently Asked Questions
How do I tell a gas defect from a contamination defect?
Recoat a small test patch and watch where the marks land. This one test separates most of the round defects, and it works because the two causes behave differently once you disturb them.
A gas defect moves. The air or vapor that caused it has already escaped, so the second coat gasses from wherever the slab happens to be releasing next, and the new marks appear somewhere else.
Contamination repeats. Silicone, oil or a release agent is still sitting on the slab, and the fresh coat pulls away from exactly the same spots it pulled away from the first time. Marks in the same places mean you have a cleaning and preparation problem rather than a moisture problem, and no amount of extra coats will bury it.
The floor has round marks. How do I tell which one I have?
Look at what the middle of the mark is doing. There are only three possibilities and each points at a different page.
A closed dome that gives when you press it is a bubble: the gas is still trapped under an unbroken film. An open puncture through an otherwise flat film is a pinhole: the gas got out, and the coating was too stiff or too thin to close behind it. A circular bare or thinned spot with a raised rim, where nothing was ever punctured, is a fisheye: the wet resin met something it could not wet and retreated from it.
Bubbles and pinholes share their causes and need different fixes. Fisheyes share neither, which is why the three way test is worth doing before you decide anything else.
Why is this page separate from the troubleshooting index?
Because they answer different questions. The index lists every defect by name, which is the fastest route if you already know the word for what you are looking at.
This page assumes you do not. It is organised by what you can see from standing height, so it works when all you have is a floor with something wrong on it and no vocabulary for it yet. If you know the name, the index is quicker.
What should I record before I start repairing anything?
The conditions and the material, because both get lost within a day and both decide whether a repair holds.
Write down when the coat went down, the air and slab temperature and the relative humidity at the time, which product and batch it was, what the mix ratio and pot life were, and how long it sat before the next coat. Photograph the defect with something in frame for scale.
Most coating failures are conditions failures, and conditions are the one piece of evidence that disappears completely if nobody notes it. A data sheet states limits for temperature, humidity and recoat window, and you cannot check a floor against those limits from memory.
Can more than one defect be present at once?
Often, and it is worth expecting rather than being surprised by. A slab pushing moisture can bubble the base coat and peel it later, and the same damp conditions that drive bubbling also encourage blush on the topcoat.
Work through them in order of what has to be fixed first. Anything to do with the slab, meaning moisture, contamination and preparation, comes before anything to do with the film, because a perfect topcoat over an unresolved slab problem fails again on the same schedule as the first one did.