Removing an oil stain on a concrete floor.

Q. I have a garage floor that has a 3x3 foot oil stain and I want to clean it up properly so I can acid stain the floor. What's the best way to do so?

A. Here are three different methods, try one or all three if the stain is really stubborn.

1. TSP: Using phosphate free TSP cleaner (Tri Sodium Phosphate), create a gallon of cleaner by mixing one cup of TSP with one gallon of hot water. Wearing eye protection and rubber gloves, pour the TSP onto the oil stain and let it soak in for 20-30 minutes. Then scrub with a plastic bristled brush and rinse with a hose. Repeat if needed.

2. Removing the fresh stain from the concrete floor will require a regular scrub brush, some liquid dish soap and water. All you need to do is squirt some liquid dish soap onto the stain and add some water. Be sure to wet down the surrounding concrete as well. This will prevent oil released during the cleaning process from causing a secondary stain. Scrub the stain vigorously and add enough water to make a rich lather of soap. The soap will emulsify the oil and lift it out of the concrete. Rinse with a hose and repeat the process if needed.

3. Older oil stains that have penetrated the surface of the concrete are much harder to remove. Make a paste of two parts hydrated lime powder and one part turpentine. Spread the paste over the surface of the remaining oil stain covering a larger patch than the actual stain. Cover the stain with plastic sheeting to help prevent the turpentine from evaporating. Leave the poultice covering on the stain overnight. Scrape off the paste and follow with a good scrubbing of detergent and water. You may need to repeat this poultice procedure as more of the stain leaches up to the surface of the concrete.