Q I spilled some battery acid on my concrete garage floor, and even though I thoroughly rinsed the area with water, the acid still left some large white spots. How can I restore the floor?
A Battery acid is tough stuff, as you’ve discovered. In this case, it appears to have etched the floor. Given the fact that you’ve already rinsed the area, you may be able to conceal the blotches by carefully brushing on concrete stain to match the colour of the surrounding surface.
If this doesn’t give a satisfactory result, stain the entire floor. To do this, first clean the concrete with a degreaser (your local hardware store will advise you). Next, dampen the floor and sprinkle on the company’s etching solution, scrubbing it in with a stiff broom. Finally, rinse the area; when dry, apply a concrete stain.