The Best Ways to Remove Stains From Patios and Walls

How to Clean Bricks, Stone and Concrete

It's inevitable: brick patios and walls get exposed to the elements or something else creates a stain: mortar, mildew, rust, paint and even graffiti. Before you attack it with your power washer, find out the best remedies for your patio or wall's particular stain, or it will not-so-mysteriously find its way back onto your brick masterpiece. Remember: there's never a quick-fix, one-size-fits-all solution to anything.

  • 01 of 06


    bricks and mortar
    Sloppy mortar with bricks. Memo VasquezGetty Images

    When 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.
  • 02 of 06


    brick stacked stone
    Mortared brick and stone can reveal efflorescence a few weeks after a project is completed. Lisa Hallett Taylor

    What, exactly, is efflorescence? You've probably seen it numerous times, but just didn't know what it's called. Efflorescence is that white, or grayish white substance that shows up on brick, stone, paver and other outdoor construction projects in which mortar is used. It happens when mineral salts in the mortar are dissolved by water, and can also be referred to as calcium hydroxide or free lime.

    It usually appears a few weeks after the project has been completed, creating a certain...MORE anxiety for the homeowners. Before complaining to your contractor though, why not tackle the cleaning project yourself?

    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.

  • 03 of 06


    mildew on wall
    Mildew and leaking damage on wall. Matthias Hauser/Getty Images

    For 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.
    • Repeat, if necessary.
  • 04 of 06


    rust stain on concrete
    Rusty stains on concrete. Jill L Wainright/EyeEm/Getty Images

    Ah, rust—it finds its way onto every metal and nonmetal surface in your yard, on your porch, patio—everywhere outdoors.

    Here's what to do:

    • 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 rinse.
    • 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...MORE small, out-of-sight area first, to make sure it doesn't create another type of stain on the ​brick or stone.
    Continue to 5 of 6 below.
  • 05 of 06


    garden chairs being painted
    Garden chairs being painted outside. Steve Cicero/Getty Imags

    Did 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 Colin or Skippy a putty knife to scrape off as much paint as possible from the patio or wall.

    What to do:

    • After he's given it his all (five minutes, tops) he can scrub at the hardened paint splotches with a metal-bristled...MORE 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 Colin or Skippy, preferably something that doesn't involve a brush of any kind.
  • 06 of 06


    graffiti and paint
    Graffiti paint, sidewalk and wall. Spaces Images/Getty Images

    Yes, graffiti happens—in every neighborhood. Drive to your local hardware store, buy a spray paint remover and follow directions. Repeat if necessary. If it doesn't work, consider painting the wall or retexturing the surface.