A word of advice: Wear a ventilation mask, long sleeves, protective eyewear and strong, synthetic gloves when applying acid. Use a long-handled, coarse-bristled brush.
MortarWhen using mortars, workers -- do-it-yourselfers included -- sometimes get sloppy. What results are mortar smears, which show up after the mortar has dried. To remove stains, use a muriatic acid solution:
- Dark bricks or stone: 1 part acid to 10 parts water
- Light: 1 part acid to 15 parts water.
- Caution: Pour acid slowly into water; never pour water into acid. Apply as directed, allow to stand for 10 to 15 minutes, then rinse thoroughly.
MildewFor mildew stains, use a solution of 1 part regular household bleach to 3 parts water, with a small amount of mild laundry detergent or trisodium phosphate mixed in. Allow to stand for 15 minutes, then rinse.
RustAh, rust -- it finds its way onto every metal and nonmetal surface in your yard, on your porch, patio -- everywhere outdoors. First, try scrubbing the rusty object with a household bleach solution of 1 part bleach to 1 part water and allow it to stand for 15 minutes, then rinsing.
If that doesn't do the trick, attack it with a solution of 1 pound of oxalic acid to 1 gallon of water. Allow this to stand for about five minutes, then rinse thoroughly. Test the oxalic mixture on a small, out-of-sight area first, to make sure it doesn't create another type of stain on the the brick or stone.
PaintDid you put your teenage son onto a painting project last summer, and he got a bit lazy, sloppy or carried away with the paint? And did he clean up afterwards? What stains? He doesn't see any wasabi green stains on the red brick patio!
Next vacation or school break, give Jason Jr. a putty knife to scrape off as much paint as possible from the patio or wall. After he's given it his all (five minutes, tops) he can scrub at the hardened paint splotches with a metal-bristled brush and cold water. If and when that doesn't do the job (seven minutes), you can have at it with a commercial paint remover, testing on a small area first to make sure it doesn't stain the brick or stone. Find another project for Jason Jr., preferably something that doesn't involve a brush of any kind.