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Cleaning stained brick takes care and know-how Our 50-year-old building has an outside wall of high-quality yellow brick, but over many years the bricks have darkened unevenly and are now unsightly. Contributing factors may be car exhaust and earlier emissions from multinational chemical plants. How might we clean and restore these bricks to their original color?

Siegrun Beckmann, Decatur, Ala.

If possible, avoid water-blasting, and especially sand-blasting, the brick. It is imperative to maintain the unscored surface of the brick for its own longevity.

One expert in the field of masonry cleaning is ProSoCo Inc., 1040 Parallel Parkway, Kansas City, Kan. 66104. The company makes commercial masonry-cleaning materials, one of which should surely strip off the unsightly accumulation of stains. For its specific material and method on your brick, call (913) 281-2700.

The nature of the stain on the brick determines the type of material and process to remove it. Follow the firm's directions to the letter. You may first want to experiment with the material in a small area.

After the brick is cleaned, to inhibit further staining, apply a masonry sealer such as one of the Sure Klean Restorers, made by ProSoCo, or equal.