Before you grind a concrete floor — whether for polishing, sealing, or resurfacing — the surface needs to be absolutely clean. Dust, oil, paint, grease, or chemical stains will clog your tooling, stain the final finish, and prevent densifiers or coatings from bonding properly. This guide walks through the **real-world process** of cleaning and degreasing a concrete slab to get it ready for grinding — the **right way**, not the rushed way.
Start with a proper vacuum or industrial broom — the slab needs to be dust-free before any chemical cleaners or degreasers go down. This also stops fine particles from clogging your grinder later. If you're in a garage or warehouse, blow compressed air into edges and corners to flush out hidden dust and grit.
Any dark, glossy patches are likely oil or grease-based — and they’ll clog your diamond tooling fast. Use absorbent clay, cat litter, or sawdust to soak up fresh spills. Let it sit for at least 30 minutes before sweeping it up. This step alone can prevent smearing or heat-glazing during your first grind pass.
Choose a pH-neutral or alkaline degreaser designed for concrete. Apply directly to grease spots or over the full floor for large surface contamination. Let it dwell for 5–15 minutes (check the label). Don’t let it dry out during this phase — you want it to actively break down oils and emulsify contaminants before scrubbing.
Use a rotary floor scrubber, auto-scrubber, or stiff-bristle broom. Manual scrubbing is fine for small areas, but mechanical scrubbing ensures the degreaser penetrates the pores. Focus extra time on high-traffic zones, machine bays, or any previously painted or sealed areas. Scrubbing helps lift any embedded grease particles from the capillaries of the slab.
After scrubbing, use water to rinse off the emulsified oils and residues. Wet vacs are ideal here — they remove the water without driving it back into the pores. Avoid pressure washers unless you plan for extended dry time. The goal is to remove every trace of chemical without saturating the slab too deeply.
Let the slab dry for 12–24 hours depending on ventilation and weather. Grinding a damp slab causes slurry smearing, glazing, or uneven bond with densifiers or dyes. You can speed dry using air movers, fans, or dehumidifiers. Use moisture tests if you're unsure — especially for old garages or basements where slab dampness lingers.
Once dry, inspect again. Some oil spots will darken back up — these may need a second degreasing round. Use acetone or solvent spot cleaning for persistent marks. If the slab still repels water in patches, you're not ready to grind. A clean, porous surface is key for smooth diamond contact.
If your job site includes drains, walls, glass, or machinery, mask or shield these areas before grinding begins. Overspray, wet slurry, and tooling debris can travel. Cleaning first gives you visibility — you know exactly where to protect, what to recheck, and where to stage your equipment for grinding day.
If you’re polishing or sealing, log what chemicals you used and where major contamination was found. This is helpful for warranty discussions and also alerts your crew (or future contractors) about possible reoccurrence of oil spots or delamination. Take a few photos and note the drying time — it’ll save time on future service work.
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