On most polished concrete jobs, the edges are what people see first — and judge the hardest. If they’re cloudy, rough, or mismatched, they’ll drag down the entire finish. Edge polishing is a blend of technique and consistency. You need the right tools, matched grit progression, and careful blending into the field grind. In this guide, we break down exactly how to edge polish a concrete floor properly — from prep to final gloss.
Always polish the open slab before doing edge work. This gives you a reference finish to match to. Trying to polish edges first almost always leads to inconsistent results — the field polish may expose different levels or highlight edge swirl. Leave 100–150mm margin for feathering later.
Your edge polishing setup should include a 125mm variable-speed grinder, appropriate dust shroud, and vacuum. Variable speed allows better control at finer grits. Avoid grinders without RPM control — they’ll burn resin pads or gouge the surface at higher steps. Keep your tooling matched in bond and grit to the main machine.
If your main floor is polished to 800 grit, your edge polishing must follow the same grit sequence: 30 > 50 > 100 > 200 > 400 > 800. Don’t skip grits just because it’s a small area. Skipping even one step causes cloudy reflections and visible transitions under raking light. Use quality metal and resin pads made specifically for hand grinders.
Straight linear grinding tends to leave cut lines and uneven scratch depth. Instead, polish in overlapping curved or figure-eight motions, blending each pass with light pressure. Take your time — edges polish more slowly than the open floor and are more prone to heat buildup or glazing.
As you polish, always extend at least 100–150mm into the main slab to feather and blend the edge polish. This creates a consistent transition and prevents a visible “halo” line. Use lighter pressure when transitioning into the field to avoid overcutting. The goal is to make the edge invisible — not more polished than the rest.
Use lower RPMs at finer grits to avoid burning or glazing. As the concrete hardens from densifier and polish, reduce pressure and slow your grinder slightly at 400 grit and above. Always check the edge temperature — overheating will polish unevenly and shorten pad life drastically.
Vacuum thoroughly or rinse wet residue between each grit stage. Look under low-angle light to inspect for swirl marks, deep scratches, or dull patches. Missed spots should be corrected before moving to the next grit — resins won’t cut out mistakes from the previous stage.
After your final grit (400, 800, or 1500 depending on job spec), compare the edge gloss to the rest of the slab. Use a flashlight or window reflection to check consistency. If the edge is brighter or duller, go back one grit and refine. Gloss variations are nearly impossible to hide after sealing or burnishing.
If your project includes a guard product or burnish pass, include the edges. Apply guard with a microfiber around the perimeter, then burnish the edge using a small hand buffer or white pad. This ensures the entire slab — wall to wall — has the same protection and finish quality.
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