| Factor | Diamond grinding | Acid etching |
|---|---|---|
| Profile achieved | CSP 2-3, consistent | CSP 1 at best, uneven |
| Removes existing coatings | Yes | No |
| Removes laitance | Yes | Partially |
| Residue left behind | Dust, vacuumed | Salts, unless fully neutralized |
| Works on hard-troweled slabs | Yes | Poorly |
| Typical bond outcome | Reliable | Unpredictable |
What CSP profile means
The Concrete Surface Profile scale runs from CSP 1 (nearly smooth) to CSP 9 (heavy scarification). Thin coatings want CSP 1-3; typical resin floor systems want CSP 2-3. That texture gives the resin mechanical keying: the coating physically locks into the pores rather than just resting on the surface.
Why acid etching fails so often
- It cannot cut through a hard-troweled or densified surface
- It etches unevenly, so bond strength varies across the floor
- It leaves salt residue that must be fully neutralized and rinsed: rarely done thoroughly
- The rinse water reintroduces moisture into the slab right before coating
- It does nothing to remove old coatings, sealers, or curing compounds
What good grinding looks like
A planetary grinder with metal-bond diamonds, connected to a HEPA dust extractor, run in overlapping passes across the entire slab including edges and corners. Corners and wall lines get a hand grinder. Afterward the floor is vacuumed, not swept, and the profile should feel like 60-grit sandpaper.
You should be able to see uniform open concrete with no shiny spots. Shiny spots are missed areas, and missed areas are where the peel starts.
The verdict
Require diamond grinding in writing. If a quote specifies acid etching, it is quoting a different, shorter-lived floor than the one you think you are buying.
Frequently asked questions
- Is diamond grinding better than acid etching?
- Yes. Grinding produces a consistent CSP 2-3 profile, removes old coatings and laitance, and leaves no harmful residue. Acid etching is uneven and leaves salts behind.
- What CSP profile do coatings need?
- Most resin floor systems need a Concrete Surface Profile of 2 to 3. That gives the coating enough mechanical keying without over-roughening the slab.
- Why does acid etching fail so often?
- It cannot cut hard-troweled surfaces, etches unevenly, leaves salt residue, reintroduces moisture, and does not remove old sealers or coatings.
- Can you coat over an old sealer?
- No. Old sealers and curing compounds must be removed mechanically. Diamond grinding is the standard way to do that.
- What does a properly ground slab look like?
- Uniform open concrete with no shiny spots, feeling like 60-grit sandpaper. Corners and wall lines should be done with a hand grinder.