No matter how skilled you are and no matter how careful you are, it's bound to happen at some time: You wind up spilling wood stain or varnish on your unsealed concrete sidewalk, patio or driveway. Most wood stains are oil-based, so you'll want to approach this clean-up job just as would an oil stain. Depending on the severity of the stain, you might be able to remove it with dish soap and a gentle scrub. Or you might have to ramp up your efforts by poulticing, a method that combines the use of an absorbent and a chemical – in the case of wood stain, acetone. Either way, it shouldn't be long before the wood stain is gone and your concrete bears no trace of the mishap.
Remove Wood Stain
Blot up as much of the wood stain as possible with paper towels or old rags. The longer the wood stain sits on the concrete, the more it will seep into the porous material, thereby making the cleanup more difficult. Dispose of the materials in a garbage bag and keep the bag outdoors until garbage day.
Cover the stain with kitty litter or baby powder, both which work as absorbents to draw the stain out of concrete. You also may use sawdust, if you happen to have an ample supply around. Cover the area with plastic wrap, tack down the edges with masking tape and let the absorbent settle in for a full 24 hours.
Sweep up the absorbent. Place it in a garbage bag and set it aside until garbage day.
Squirt some liquid dish soap onto the remnants of the stain, spray it with a little water and use a nylon brush to produce a heavy lather of soap. Scrub the stain until it disappears.
Soak up this dirty, soapy mess by covering the area with absorbent. Remove all of it with paper towels or old rags. Then hose down the area with hot water. If traces of the stain remain, repeat your efforts, beginning with covering the stain with kitty litter or baby powder. Some stubborn stains might require multiple scrubs.
Attack powerhouse stains by mixing a poultice that includes an absorbent, such as diatomaceous earth or kitty litter, and acetone, the active ingredient in nail polish remover. Wear protective gloves and mix the two ingredients in a bowl until it forms a thin paste that resembles the consistency of peanut butter.
Spread a liberal layer of paste over the stain, or one that is about 1/4-inch thick. Cover the poultice with plastic wrap, tack it down with masking tape and let the poultice dry thoroughly. It could take 24 hours, or even longer depending on weather and humidity, for the paste to dry. But don't try to rush the process; the acetone needs time to attack the stain while the absorbent works on both elements.
Scrape off the poultice with a plastic tool, such as a spatula. Wipe the area with a damp cloth or paper towel to reveal your restored concrete surface.
Varnish and Paint
You can remove varnish and paint with a poultice, as well, using a solvent designed for the particular type of paint of varnish. Choose the product carefully, as some removers and thinners contain harsh chemicals that will require you to wear protective gear and work in a well-ventilated environment. More acidic products may also etch the concrete. These products tend to work quickly. By contrast, water-based removers and thinners, while gentler, might take longer to dissolve the varnish.
Mix just enough absorbent to thicken the stripper or solvent. Apply the mixture and scrape up the varnish with a plastic scraper after it has softened. Leave it on only long enough to loosen the varnish to minimize etching.