Sealer on polished concrete fails at the interface more often than in the film. A surface polished to 2000 grit has almost no profile for a coating to key into, and that is a design decision, not a defect.

Profile scale

CSP	Surface	Coating suitability
1	Very smooth, closed	Thin sealers only, high risk
2	Smooth, slight texture	Most sealers with primer
3	Light texture, fine aggregate visible	Good for high-build coatings
4-5	Open texture, coarse aggregate	Not a polished finish

Two ways to get bond

Mechanical: finish at 400-800 instead of 2000 where a sealer is planned. The satin surface carries enough profile and still reads as polished in most commercial settings.

Chemical: use a primer designed for dense substrates. It provides the bond the profile cannot. Skipping the primer on a 2000-grit floor is the most common cause of delamination.

Preparation without wrecking the polish

• Clean with neutral or mildly alkaline chemistry; acid opens the densified layer.
• Scrub edges and joints by hand; machine heads cannot reach them.
• Rinse and allow full drying. Moisture under a sealer produces white patches.
• Do not acid etch to create profile on a polished floor. It blotches and destroys the finish you are protecting.

Test before committing

Apply the sealer system to a 1 m2 panel, cure per the data sheet, then test adhesion with a cross-hatch or a pull-off test. A 1 m2 test costs minutes; a failed 500 m2 application costs the floor.

Failure signs within months

White edges, blistering in traffic lanes, and sealer peeling in sheets all point to bond failure rather than wear. When that appears, strip the film, re-profile to CSP 2-3, prime, and reapply. Adding another coat over a delaminating film simply adds weight to the sheet that will peel.