Q. The brick around my fireplace has gotten black in some places. How do I clean it? Can I seal the brick afterward to keep it clean? C.L., Chicago
A. Cleaning and sealing masonry is always tricky because of its porous nature and the texture of bricks and mortars, says Howard Clark, licensed construction supervisor from Hopkinton, Mass.
To remove soot on face bricks, first try scouring with a stiff, dry brush as you continuously vacuum over the bricks. If the results are not satisfactory, try washing just the sooty brick with a brush and a light solution of dishwasher powder or TSP-type cleaner (both nonsudsing ). This will most likely dissolve the soot rather than remove it, so that it will soak further into the brick and become less noticeable.
Blot the moist brick with an old Turkish towel.
If this is inadequate, soak all the bricks well with water without any further scrubbing. When the brick is saturated it will be less likely to absorb cleansers and sooty water. Now thoroughly scrub the entire face with the TSP solution. With a wet/dry vacuum, suck up the soiled water as you go. A powdery film may form as the brick dries; vacuum this away.
Mr. Clark does not recommend applying sealers to fireplace masonry. Some yellow with age and are hard to maintain. Others don't stand up to the heat generated by the fireplace.
If you pursue your options at a professional's paint store, make sure you mention that you're applying this to a fireplace, as heat will likely be a factor.
Soot on face brick points to other fireplace problems. If you smell smoke occasionally, you may have a problem with proper draft, and should examine your chimney, damper, or flue. You may want to seek advise on fire-building techniques, too.
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