Average response time: under 24 hours
Remove thick epoxy with a planetary grinder fitted with PCD or soft-bond diamond tooling, running at 0.3 to 0.5 mm per pass across three to four overlapping passes. Use a 16/20 or 30/40 metal bond after the PCD step to clean residue, then finish with 60/80. Plan for 1 to 2 hours per 10 m² for 2 to 3 mm build-up, and always run a HEPA extractor because epoxy dust is a respiratory irritant and will trigger dust complaints from adjacent tenants.
A 2 to 3 mm epoxy build-up flexes under a standard metal-bond segment, which skates on top of the coating instead of cutting. You need a tooling edge that chips and fractures the epoxy rather than rubbing it. PCD inserts are the fast route, but on mid-range budgets, soft metal bonds and copper-bond transitional pads also shear the film and leave the slab clean, which is why many restoration crews keep three tooling types on the truck for coating removal jobs.
For example, the JOY-RFP-C2 copper-bond transitional pads bridge the gap between aggressive grinding and resin polishing: they cut residual epoxy film without digging into the slab, which is exactly what you need after the first PCD pass has removed the bulk coating and left a thin, smeared film behind.
Mount PCD scraping segments or a 16/20 soft-bond trapezoid plate. Set the grinder to light pressure and walk at 2 m per minute. The epoxy will peel off in curls or flake off in chips. Do not press down; let the tooling shear the coating, because extra pressure just loads the segments with resin and glazes them within minutes.
Switch to 30/40 or 60/80 metal bond to plane away the thin film left behind. This pass also opens the concrete surface for the new coating. Run two diagonal directions so the scratch pattern stays flat and avoids the circular swirl marks that show through a clear epoxy top coat.
Finish with 120 grit metal bond or a copper-bond transitional pad to leave a clean, profiled surface. Stop when you see uniform sand aggregate and no glossy epoxy flecks under a flashlight at an angle. Raking light is the best inspection tool, because it catches thin film that looks clean under overhead lights.
On thick build-up, 0.3 to 0.5 mm per pass is the sweet spot. Going deeper loads the segments with epoxy and glazes them in minutes. Run the planetary heads at 1,200 to 1,500 rpm and keep the machine moving; holding still melts the epoxy into a smear that takes two more passes to remove. If the tooling loads up, dress it on an abrasive brick or a worn concrete patch to clear the resin, because a glazed segment will not recover on its own. Two light passes always beat one heavy pass, even though they look slower on paper.
Epoxy dust is fine and chemically irritating, so the HEPA extractor must be properly sized. A 600 mm grinder needs 300 to 400 CFM; underpowered extraction lets the dust cloud escape sideways. Wear a P100 respirator, not a dust mask, and ventilate the space. On jobs where the coating is older than 1980, test for lead before grinding, because lead-based epoxy mastics are abated, not ground, and abatement rules apply once lead is confirmed.
If the epoxy is over 4 mm thick, or it is a very heavy mortar bed with broadcast quartz aggregate, grinding alone is slow and wears out the tooling extremely fast. Bring in a scarifier with flails or a shot blaster for the bulk removal, then finish with the grinder. The grinder is the precision tool, not the brute-force tool, and mixing methods on the same floor saves hours compared with trying to force one machine to do both jobs. For edge work where the main plate cannot reach, small trapezoid holders such as the JOY-TP-R3 mounted on an edger strip the perimeter band cleanly, and they swap between grits without tools so the edge crew keeps pace with the center of the floor.
After the final pass, vacuum thoroughly, then run a damp white rag test. If the rag comes up clean, the slab is ready for primer and new epoxy. Wait 24 hours after the last grinding pass before applying primer, because fine dust settles out of the air and can film over the surface if you rush. For the full sequence of PCD, metal-bond, and transitional tooling, browse the concrete grinding tooling catalog and stage all grits on site so you never stop mid-floor to order another set of segments, because downtime on a coating-removal job costs more per hour than on a new install.
Written and reviewed by JOY TECH - an SGS & BV audited, CE/RoHS certified diamond tools manufacturer founded in 2004, exporting to 50+ countries.
Our factory and quality management system are audited by SGS and Bureau Veritas. Products meet CE/RoHS requirements and every piece is 100% inspected before packing.
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