Before you power wash or paint/seal your garage floor, you’ll want to attack any oil, grease or rust spots.

1. Cover grease stains with a layer of sawdust or cat litter. These materials absorb excess oil remarkably well. Leave the sawdust or cat litter on the floor for at least one day.
2. Use a push broom with rigid bristles to sweep up the sawdust, cat litter and dirt.
3. Pour dry dishwasher detergent or a concrete cleaning agent on the stain. Let the detergent sit for 45 minutes, then pour boiling water on the area and vigorously scrub the stained section with the broom.
4. For stubborn stains, use muriatic acid in combination with your pressure washer set to at least 1200 PSI. Apply the acid according to the manufacturer’s instructions. Allow it to soak for a few seconds and rinse. Use baking soda on the cleaned area to neutralize the acid, and rinse.

Combine an ounce of trisodium phosphate (TSP) in a gallon of hot water. Wet the concrete and use a push broom with rigid bristles to scrub. Let the solution soak into the concrete for 10 to 15 minutes. Rinse thoroughly.

Small cracks can be filled with an epoxy paste. Once you’ve filled the crack, scrape excess epoxy so that it’s flush with the floor. After the repair dries completely, do some light sanding for a smooth finish.

For larger cracks, overfill with an epoxy paste. Let the repair dry. Then grind the area so it’s flush with the floor.

Moisture Test
If you think that moisture issues might prevent paint or sealer from bonding, here’s a simple way to find out: Cut out a 3-ft x 3-ft square of plastic sheeting and tape it down completely to your garage floor. If after a day or so, water collects on the underside of the plastic, you’ll need to put down a good vapor barrier before the primer coat.

Sealant/Etching Test
If you’re unsure whether your garage floor has previously been sealed, you can pour water on it to perform a simple test. The water should soak into the concrete relatively quickly. If it beads up or just sits there for a long time, the cement has been sealed before and probably needs to be etched before you can re-seal or paint the garage floor.

Etching the Floor
To etch the floor of your garage, apply a commercial concrete etcher, being careful to follow the manufacturer’s instructions. If the etcher fizzes up as it’s applied, you know that it’s working. Let the floor dry overnight. The concrete will now have a grainy texture, which offers a better surface for the paint to grip.

To prevent future staining, to minimize concrete dust, and to make it easier to sweep, you can seal your garage floor. If you are planning to also paint your garage floor, applying sealant can act as a primer. Priming prior to painting can help achieve better adhesion if moisture is an issue or if the concrete is dusty and “weak.”

Choose a product that is either a water-based floor epoxy or a solvent-thinned epoxy. Use a nylon brush along the edges of your garage and use a roller — lint-free, all-purpose, solvent- and water-resistant with a medium nap — to apply the rest of the sealant. Apply sealant liberally but be sure to roll it out evenly. If you’re going to paint the garage floor, allow the sealant/primer to dry thoroughly (at least 8 hours).

When selecting paint for your garage floor, make sure to choose an epoxy paint created especially for garage floors. Mix the paint well and apply a thin, even first coat. Cut in along the edges of your garage with a brush and then use a roller with a medium nap to apply the rest of the paint. Let the first coat dry thoroughly (about 24 hours).