Interior fireplace discolored


Old 03-10-00, 03:09 AM
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The huge fireplace in my livingroom gets a white blotchy build-up which grows progressively worse. I can't find a product to totally remove the white substance. What should I use to get it off?
Once it is gone, is there a way to keep it from returning?
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Old 03-12-00, 10:27 PM
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There are four basic types of white stains on brick: efflorescence, lime, those from carbonates and sulfates (AKA "white scum"), and moisture build up behind a sealer.

Each type of stain can be treated, but note that masonry cleaners can contain acids, alkalies, or poisons. Thus it's important to read the container labeling and follow directions to the letter. If household cleaners or home remedies are being used, quit it, because they may aggravate or fix the stain making it almost impossible to remove.

In almost every case it's pointless to treat the stain until the brickwork is completely dry. Along the same line, moisture migration through the brickwork must be cut off. Otherwise it will return, time after time. An exception is insoluble salts formed on dry brickwork when combine with CO2 from the air.

Efflorescence is white crystalline powder. It can be bushed off and it's soluble in water. Run a wet finger over the stain. Does it steak or dissolve? Efflorescence can be brushed off with a stiff brush when the brickwork is dry. If that fails, efflorescence removers can be purchased from a masonry supply. (Use a stiff brush twice before resorting to a remover).

Lime stains have two appearances: white along the mortar joints plus migration to the brick and spalls (pop-outs) in the brick with a white dot in the spall plus migration around it. Purchase a lime remover from a masonry supply.

If wax or a non breathable masonry sealer has been applied it must be removed. Moisture behind a breathable masonry sealer will cloud and discolor while continued heavy moisture exists in the brickwork, but will escape through the sealer once the moisture content goes down. Purchase a sealer remover from a masonry supply.

Carbonates and sulfates (AKA "white scum") are slightly soluble to insoluble in water. The stain can appear on damp or dry brickwork. The insoluble portion combines with CO2 from the air. On damp brickwork the soluble portion leaches from the brick or mortar. Afterward it may fix with CO2 to form an insoluble stain. Run a wet finger over the white stain. Does it come off or streak? Purchase a "white scum" remover from a masonry supply.

To keep it way: solve the problem of moisture migrating through the brickwork, then possibly apply a breathable masonry sealer, and reduce CO2 levels during the winter for insoluble stains.

The moisture source can be from the ground (soaked soil or improperly graded, a poor bond break between earth and the brickwork, leaking pipes), air (under the house, in the attic, inside rooms, or simply brickwork exposed to the elements), poor caulking between the brick and siding, roof flashing, snow against the chimney, chimney cap, chimney crown or the bond beak between the crown and flue, the flue itself, cracks in the mortar, cracks in the brick, or something relative like leaking gutters. Find it, then treat the cause.
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