A solution for removing white stains on bricks

House Doctor | Gary Dymski

June 9, 2005

The aluminum trim around my windows has stained the brick facing on my house. Over the years, water has washed over the aluminum, and the result has been this white, oxidizing stain on the brick. I've tried power washing, detergents and paint remover, but nothing seems to work. Any ideas? -- Herb F., Bethpage

You say detergents haven't worked, but did you apply them correctly? First, try a trisodium phosphate substitute, available at hardware stores and home centers. Dissolve the powder in warm water, about a tablespoon for each quart. Work the solution into the brick with a stiff-bristled brush, let it set for several minutes. Rinse with water. You might have to repeat a couple of times. You also can make a paste and apply it over the stain. Again, let it set for several minutes, then rinse with water.

Any type of household concrete or brick cleaner also can be used. Zep, for example, makes a concrete cleaner available in hardware stores and home centers. Masonry cleaners that have phosphoric acid also might work; read and follow the application instructions on the labels.

If you don't have much luck with cleaners, try the claylike material called Fuller's earth. Look for it in hardware stores or masonry supply yards. Fuller's earth has excellent absorption properties and is rubbed into the brick to lift stains of oil and grease.

House Doctor Recent columns

As a last resort, try muriatic acid. This is perhaps the most dangerous household product you can purchase for cleaning. Muriatic acid can burn skin and eyes, so wear safety goggles and rubber gloves and protect your skin with a long-sleeved shirt and long pants. Because the fumes can be nasty, too, wear a respirator, a paper filter that fits over the mouth and nose.

Dilute the acid with water (1 part acid to 10 parts water will be plenty strong). Remember to add the acid to the water in a pail to avoid splashing. Applying the acid solution is tricky. Splattering it on the brick with a brush can cause damage to plants near the foundation. Try spraying the solution with a plastic spray bottle. Because the acid eventually will corrode the spray mechanism, you probably will have to dispose of it when you're finished.

Wet the brick first, then spray on the acid solution. Brush gently with a long-handled, soft-bristled broom and let the solution set for several minutes. Rinse with water and then let dry. If the stain hasn't been lifted, repeat.

Before applying, remember that the acid solution could discolor the brick. Test the strength of the mixture on a hidden section of brick first, and then adjust it accordingly.