The Golden State: Where & How to Live, Secure, Visit, Enjoy and Thrive in California

Care And Repair Of The House

3. REMOVING EFFLORESCENCE FROM WALL SURFACES

Efflorescence is the accumulation of salts upon the outer surface of a wall, particularly noticeable on those built of brick. It is a whitish, crystalline deposit resembling hoarfrost or mold, and it usually appears in patches.

These salts may exist in mortar, brick, concrete stucco, or other masonry materials. They are brought into solution by water in the wall, carried to the outer surface, and deposited there as the water evaporates.

Efflorescence may be more pronounced in new work, owing to an excessive amount of water in the mortar and a maximum amount of salts in the new materials. As the building becomes older, however, the accumulation often disappears without being removed.

It is commonly found in places where the wall is subjected to frequent wetting, as below window sills and copings, or near gutters and down spouts where there may be leakage. A prolonged wet spell may also bring it out in other places.

Water gets into the wall in various ways. In addition to the absorption of rain, melting snow, and humidity from the air, it may rise from the ground through mortar joints or seep in through cracks around window or door frames.

To Remove Efflorescence.

Efflorescence may sometimes be removed by brushing the spots vigorously with a stiff fiber or wire brush.

If this does not produce satisfactory results, prepare an acid wash composed of 1 part of muriatic acid and from 4 to 10 parts of water, and scrub the spots well with a fiber brush dipped in the solution. Avoid the mortar joints as much as possible during the scrubbing process and when the work is finished, rinse the surface of the wall with clear water. It is advisable to wash the surface again with a diluted solution of ammonia (1 pint of ammonia to 2 gallon of water) to remove every trace of acid.

The deposits may reappear from time to time and require additional washings, but will disappear entirely when the supply of soluble salts in the materials has been exhausted.

Precautions Against Recurrence.

Since efflorescence is caused by the evaporation of water which has previously been absorbed, it is obviously important that the opportunities for this absorption be reduced as much as possible, if the trouble is to be checked.