Stain, stain go away

Q: This spring I discovered that the compressor I had stored in my garden shed had sprung a leak in the tank and there was a large oil stain (wet) on the concrete floor. First I tried the “cat litter” treatment, but that did not lift all of the stain. Then I tried your idea of the ready-mix concrete and let it sit 24 hours. Still no removal. At wits’ end, I tried straight application of Clorox! Still nothing! Have I messed it up so much that now I am destined to live with that stain? — Larry M., Spokane, Wash.

A: Never give up, Larry! Well, actually — you might have to give up, eventually, but there are still some homegrown methods to try.

The bleach may have made the problem worse, but considering that it’s a large stain, maybe not.

Avoid really serious chemicals, like muriatic acid, which removes the top layer of concrete. That’s more useful when cleaning and resurfacing an entire floor or driveway.

Some folks swear by common household agents to take care of serious stains. In addition to kitty litter and ready-mix concrete, I’ve heard of using WD-40 to “float out” the oil stain on another oil-based liquid; spraying oven cleaner (a degreaser) over the stain; or soaking sawdust in white mineral spirits and covering the stain for a couple of days. Whatever you try, test a small section of the concrete first, and rinse the chemical away completely before trying something else.

Consider purchasing a concrete cleaner from the home-improvement store, or a heavy-duty degreaser from an automotive or home-improvement store. You still want to soak up as much oil as possible. Then, rent a pressure washer, which can literally drive the stain right out of the porous concrete.