Garage Floor Preparation for a No-Grind Epoxy Application

Work in sections of about 10' × 10'. Lightly dampen the concrete, apply the cleaner/etcher evenly, scrub it in with a stiff broom until the foaming stops, then rinse the section completely before it dries. Never let the etching solution dry on the floor; rinse while it's still working.

• Why sections: Working in large areas makes it hard to rinse before the solution dries, which leaves a white, powdery residue.
• Scrub, don't mop: Scrubbing with a stiff broom works the solution into the pores. Mopping just smears it across the surface.
• How you'll know it worked: A properly etched floor feels like fine sandpaper. If areas still look shiny or feel smooth, re-etch those spots.

The white haze is residue from the etching reaction, a mix of loosened cement particles and mineral salts. It forms when the solution dries before it's rinsed or isn't rinsed thoroughly enough. It must come off before coating, because a coating bonds to the loose powder instead of the concrete and can later peel off with the dust stuck to its underside.

• Removal: Scrub and rinse again, or pressure-wash the area. Stubborn residue sometimes needs a second, milder etch to lift it.
• Prevention: Keep the concrete wet the whole time you're etching, and rinse each section as soon as the scrubbing is done.
• Optional check: For acid-based etchers, a pH strip on the wet floor after the final rinse should read at least 6.0. A lower reading means acid is still in the pores.

Each contaminant needs its own method. Scrape off drywall mud and dried adhesive, treat rust stains with a concrete rust remover, and kill mildew or algae with a diluted bleach solution, then rinse. Everything must be removed before the general clean-and-etch step, because an etch alone won't cut through these materials.

• Drywall mud: Scrape it off with a floor scraper, then scrub. It's water-soluble, but residue left in the pores blocks adhesion.
• Glue and mastic: Scrape off as much as possible. Thick adhesive residue often needs a small angle grinder in that spot.
• Mildew and algae: Bleach is appropriate for biological growth like mold and mildew. Rinse thoroughly afterward so no bleach residue remains.
• Peeling paint: Scrape off anything loose or flaking. Whether well-bonded old coatings can stay is covered on the Understanding Concrete page.
  
  

A pressure washer is a good rinsing tool and helps with heavy pre-cleaning, but it doesn't replace scrubbing with a degreaser. Use it to blast off caked-on dirt before cleaning and to rinse the floor thoroughly after etching. Then remove all standing water with a squeegee, broom, or leaf blower.

• For oil: A pressure washer helps rinse out oil after a degreaser has broken it down, but it won't lift set-in oil on its own.
• For road salt: High-pressure water can drive salt crystals deeper into the concrete. Dry-brush salt deposits off first.
• After washing: Get water out of corners, low spots, and control joints, and push it out the garage door.

Yes, but only the repairs, not the whole floor. A small angle grinder with a diamond cup wheel levels cured crack and patch repairs flush with the surrounding concrete and smooths edges near walls. This spot grinding keeps repairs from showing as ridges and helps the coating bond evenly across the floor.

• Dust control: Use a dust shroud and shop vacuum, since even spot grinding creates a lot of fine dust.
• Feather the edges: Grind the edge of each repair down to bare concrete so no raised outline shows through the finish.
• PPE: Wear eye protection, a respirator, and hearing protection whenever grinding.

Tape along the base of painted walls with a 1/8" gap above the floor surface, so the coating doesn't bond to the tape. Tape around water heaters, HVAC units, and other fixtures you can't move. Apply a strip set back 1 inch from where the garage door meets the floor, so no coating extends past the door's closing line.

• Driveway edge: The rounded edge at the threshold where the floor meets the driveway needs careful taping, so coating and flakes don't bond to the driveway.
• Press it down: Firmly burnish every tape edge so coating can't bleed underneath.
• Tape timing: You have about 45 minutes to 1 hour after each coat to pull the tape. Pull slowly and evenly from each end.
• Mask first, mix second: Don't mix any product until all masking is complete.

No surface grinding is needed with the WiseBond system. SkipGrind No-Grind Concrete Primer lets epoxy coatings bond to properly prepared concrete without mechanical grinding. After cleaning and etching, SkipGrind chemically bonds to the concrete and creates the surface the floor epoxy mechanically bonds to.

• What the etch does: KretePrep Concrete Cleaner, Degreaser & Etcher removes contaminants and opens the concrete pores.
• What SkipGrind does: It penetrates the open pores and forms a chemical bond with the slab.
• What the epoxy does: It locks mechanically onto the SkipGrind layer.
• The only grinding involved: A small angle grinder with a diamond cup wheel is used to chase cracks and level patch repairs flush, not to profile the whole floor.
• The one exception: Mirror-burnished slabs still need full diamond grinding.

KretePrep Concrete Cleaner, Degreaser & Etcher handles cleaning, degreasing, and etching in one product, so you don't need separate products for each step. KreteBond Concrete Crack Filler is a two-part filler for cracks and holes that cures in about 60 minutes, then sands or grinds flush. Both are designed to work with SkipGrind Primer as one system.

• KretePrep mix: Combine 1/3 gallon (43 oz.) of concentrate with 1 gallon of water. One gallon of concentrate makes 4 gallons of premix, and hot water speeds up cleaning and etching.
• KreteBond mix: Mix equal parts A and B (1:1) for 1–2 minutes, and only mix what you can apply in 2–4 minutes.
• Why use a matched system: Products from different manufacturers can conflict. A matched cleaner, filler, and primer removes that guesswork.

It depends on the primer. Most epoxy primers require fully dry concrete. SkipGrind Primer is the exception: it's designed to go over a damp, but not wet, floor right after cleaning, etching, and rinsing. Remove all standing water so the surface is uniformly damp, with no puddles in corners, low spots, or joints.

• How to get "damp, not wet": Squeegee, broom, or leaf-blow standing water out through the garage door.
• Why it matters: Puddles dilute the primer and leave weak spots. Uniform dampness lets SkipGrind penetrate evenly.
• Readiness check: A water drop that soaks into the concrete means the surface is porous enough for SkipGrind to bond. Beading means more cleaning or etching is needed.
• Don't confuse damp with slab moisture: Moisture rising up from below the slab is a separate problem, checked with the plastic sheet test

A properly prepared garage floor is clean, structurally sound, porous, and free of anything that blocks adhesion. That means repairing cracks and voids, removing every contaminant, and opening the concrete pores so the primer can soak in and bond. Even the highest-quality coating can fail on contaminated or poorly prepared concrete, which is why prep matters more than the coating itself.

• What has to come off: Dust, dirt, oil, grease, drywall mud, peeling paint, glues, sealers, curing agents, efflorescence, rust, algae, mildew, and any other contaminant that can prevent adhesion.
• What good prep prevents: Hot tire pickup, peeling and delamination, and poor penetration into the concrete pores.
• The industry consensus: Most installers describe surface prep as the most important step in any epoxy floor project, because epoxy needs direct contact with sound concrete.

Widen ("chase") each crack with an angle grinder and a crack-chasing blade, vacuum out the dust, fill it with a two-part crack filler, then grind or sand the cured repair flush with the floor. WiseBond's prep method uses a 1/8" crack-chasing blade cut about 1/4"–3/8" deep, and a filler that cures in about 60 minutes before leveling.

• Why chase the crack first: Widening the crack exposes clean, sound edges and gives the filler room to anchor deeply.
• Coatings don't fill cracks: Liquid coatings run down into cracks rather than filling them, so a filler with body is needed if you want the crack to disappear.
• Feather the edges: Spread the filler slightly past each side of the crack and level it afterward, so the repair doesn't show through the finished coating.

Wait until the filler is fully cured and has been sanded or ground flush with the surrounding concrete. KreteBond Concrete Crack Filler cures in about 60 minutes. Many other crack fillers need 24 to 48 hours before they can be leveled and coated. Coating over filler that hasn't fully cured is one of the most common DIY prep mistakes.

• How to tell it's cured: The filler should be hard enough to grind without smearing or gumming up the grinding wheel.
• Level before you clean: Repair and grind cracks first, then clean and etch the whole floor, so grinding dust doesn't end up on a freshly cleaned surface.
• Working time is short: KreteBond gives you 2–4 minutes once mixed, so mix small batches, equal parts A and B, as you go.

Yes. A full flake broadcast hides color differences, but it does not hide depth: voids, cracks, and surface imperfections show through the finished coating if they aren't repaired first. Unfilled cracks also leave weak spots where the coating can chip or crack over time.

• Hairline vs. structural cracks: Very fine surface cracks are less visible under flake, but any crack you can catch a fingernail in should be chased and filled.
• Loose sections: Remove any concrete that is loose, chipped, or surrounded by cracks before filling.
• Check for raised edges: If one side of a crack sits higher than the other, grind the high side flush. A coating can't level a step in the slab.

Start by absorbing any fresh oil, then scrub the stain with a concrete degreaser and hot water and rinse thoroughly. Repeat until the area no longer shows an oily sheen. Deep, old stains may need several rounds or a poultice. Residual oil prevents adhesion, so the goal is to remove the oil from the pores, not just lighten the stain.

• Hot water helps: Heat lowers the oil's viscosity, so it breaks down and rinses out faster.
• Poultice for stubborn stains: Cover the degreased area with an absorbent such as clay cat litter or Portland cement, let it sit to draw out the remaining oil, then sweep it up.
• Skip bleach: Bleach only lightens the stain's color and doesn't remove the oil. It is meant for mold and mildew, not petroleum.
• The final check: After cleaning, a water drop should soak into the stained area the same way it soaks into clean concrete.

Fish eyes are small round craters where wet coating pulls away from a spot on the surface, almost always because of oil, grease, wax, or silicone contamination. The coating can't wet out the contaminated spot, so it retreats from it. Prevent them by fully degreasing the floor and treating it like a clean room once it's prepped.

• Clean room rules: Keep greasy power cords, shoes, and tools off the cleaned floor. Even tiny amounts of oil or grease can cause fish eyes or adhesion problems.
• Hidden sources: Silicone sprays, tire shine, and polish overspray are common culprits. Even a small amount of silicone on a rag or in dust can contaminate a surface.
• If they appear: The contaminated area has to be cleaned and recoated. Fish eyes can't be fixed by rolling over them.