The Prep Question
Diamond Grinding vs. Acid Etching
A coating is only as strong as what it’s bonded to. How the concrete gets prepped is the single biggest factor in whether a floor is still stuck down in five years.
Two ways to do it, and they are not interchangeable
Before any epoxy or polyaspartic comes out of a bucket, the concrete underneath has to be prepped. There are two ways that happens: acid etching, and diamond grinding.
The difference isn’t cosmetic, and it isn’t a preference. One of them removes what’s sitting on your floor. The other doesn’t.
What acid etching actually does
Acid etching uses a diluted acid solution, usually muriatic acid, mopped or poured across the floor to chemically react with the surface and roughen it slightly. It has been the industry default for decades because it’s cheap and fast — no equipment to rent, no dust to manage, done in an afternoon.
The problem is what it doesn’t do. Etching is a surface-level chemical reaction, not a mechanical one, so the profile it creates is shallow and inconsistent. Two spots on the same floor can etch differently depending on the concrete’s original finish and porosity. It’s also weather- and technique-dependent — temperature, dilution and dwell time all change the result, so the same product performs differently from one driveway to the next.
Critically, etching does not remove what’s actually on the surface: oils, sealers, laitance — the weak, powdery top layer that forms as concrete cures — or any existing coating. Etch over any of those and the new coating is bonding to the contaminant, not to the concrete.
What diamond grinding actually does
Diamond grinding uses a machine with diamond-segmented abrasive discs to mechanically cut into the top layer of the concrete. It strips away laitance, old coatings and surface contaminants, and leaves behind a uniform mechanical profile — real texture the coating can physically key into, not a light chemical scuff.
Because it’s mechanical, the result is consistent from one end of a garage to the other, and from one job to the next, regardless of temperature or how the original concrete was finished.
The tradeoff is real. Grinding takes longer, costs more than a bottle of acid, and produces dust that has to be managed with an extractor running the whole time. That is exactly why it gets skipped on cheaper jobs — it’s the easiest line item to cut from a quote without the customer ever knowing, until the floor tells them.
Why the difference shows up later, not on install day
An etched floor looks identical to a ground floor on day one.
Both take the coating. Both cure. Both look sharp in a photo that afternoon. The difference doesn’t appear until the bond gets tested by real life — hot tires, moisture pushing up from below, seasonal temperature swings.
A coating over an etched floor is anchored to a shallow, inconsistent surface, and that kind of bond tends to let go. When it does, it shows up as lifting, peeling or bubbling — typically within the first year or two, well after the install crew is gone and well inside a floor’s expected life.
A coating over a properly ground floor is mechanically locked into the concrete itself. That is not a guarantee against every failure — moisture vapor coming up through untested concrete can undermine even a well-prepped floor — but it removes the single most common and most preventable cause of early coating failure.
The question worth asking any contractor
If you’re collecting quotes for a garage, basement or shop floor, ask directly:
“Do you grind the floor, or acid etch it?”
It’s a fair question and a good filter. If the answer is etch — or if prep isn’t mentioned in the quote at all — that’s worth knowing before you spend the money, not after the floor starts lifting.
How Sterling does it
Every floor is diamond ground, wall to wall, before any coating goes down. No exceptions.
It appears as its own line item on every proposal and every invoice, not buried inside a bundled price — so you can see exactly what you’re paying for and exactly what’s being done to your floor before it ever gets coated.
We also test your floor for moisture before we quote, because prep is only half of what decides whether a coating holds. Here’s how the coatings themselves compare.
Questions
Is acid etching ever acceptable?
Not on a floor we’re putting our name on. It cannot achieve a consistent mechanical profile, and it leaves behind the contaminants that cause most coating failures.
Does grinding damage my concrete?
No. It removes the weak top layer — the laitance — and exposes sound concrete underneath. That’s the layer you want the coating attached to.
What about the dust?
We grind with dust extraction running the entire time. It’s slower and it costs more, and it’s the difference between a clean job and a garage full of silica dust.
My existing floor is peeling. Can it be re-coated?
Usually, yes — but the old coating has to come off first, and that’s grinding work. We’ll tell you what’s involved after we look at it.
Read next
Why coatings fail from underneath
Prep is one of the two things that decide whether a coating stays down. This is the other one — and it’s the one you can’t see, because it happens below the floor.