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Grind concrete before epoxy to remove laitance, coatings and contamination and to create the surface profile the epoxy spec requires, usually CSP 3 to 5. Grind with coarse metal-bond diamond segments, clean the floor thoroughly with a vacuum and wash, patch cracks and holes, and test the moisture level before coating. Epoxy fails on floors that were not ground, were left dusty, or were too wet. The grinding is the foundation; the coating is only as good as the prep. For the right tooling on this job, see coarse metal-bond grinding discs, double rhombus profile discs.
Epoxy needs mechanical grip. A troweled concrete surface is too smooth, and laitance and old coatings block adhesion. Grinding with coarse metal-bond segments removes the weak layer and creates a rough profile the epoxy flows into and locks onto. Skipping the grind is the number one cause of epoxy delamination: the coating looks good for weeks, then peels in sheets. Grind every floor, even one that looks clean. Related tooling is available in our single rhombus segment discs range.
Read the epoxy spec for the CSP it requires. Most systems specify CSP 3 to 5, which coarse grinding produces. Too fine a profile under-adheres; too coarse a profile needs more epoxy to fill and can show texture through the coating. Grind with the appropriate coarseness, check the profile with a CSP comparator card, and adjust. If the epoxy is self-leveling, the profile still matters for the primer bond.
Grinding cannot fix a wet slab. Epoxy fails from moisture vapor pushing through and from oils that grinding smears across the surface. After grinding, test for moisture with a plastic sheet taped overnight, or a calcium chloride test for large floors. If oil contamination is visible, grind deeper or use a degreaser poultice before coating. The floor must be clean, dry and profile-correct on the day the epoxy goes down.
A> Not recommended. Without a profile, epoxy has no mechanical grip and will delaminate under traffic. Grind to the spec's CSP first.
A: Apply the primer the same day, after the floor is vacuumed, washed and dry. Grinding dust must be fully removed; dust between the floor and epoxy destroys adhesion.
A: Coarse metal-bond segments, roughly 16 to 30 grit, to produce CSP 3 to 5. Check the epoxy spec and use a comparator card to confirm the profile.
Grinding before epoxy is non-negotiable: it removes the weak layer and creates the profile the coating needs to bond. Choose the right CSP, grind clean, patch first, and test moisture before coating. Do the prep right and the epoxy will outlast the building; skip it and the coating will fail.
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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