We recommend a light dry sand blast where possible or removing the white powder with a stiff bristle (not wire) brush. Also recommended is the use of high-pressure chemical cleaning equipment designed to energize the water by heating it. The force of the hot water and chemical hits the substrate with needed impact to remove efflorescence and mortar stain without damaging the masonry surface.
Preventing Efflorescence From Coming Back.
Allow masonry to dry sufficiently before applying waterproofing! Three or four days may be required, depending on weather conditions. In general the safest practice is to apply waterproofing as soon as the surface is dry to a depth of at least one half inch. Residual moisture in the wall will escape to either the inside or outside, (the warmest side). Efflorescence deposited on a waterproofed surface is more easily removed. In addition, new waterproofing will penetrate through existing efflorescence.
If, however, a building is erected during late spring, or early summer, a more practical approach is to delay waterproofing until after the walls have thoroughly dried and have been cleaned. Naturally, “dry” cleaning is preferable. If efflorescence reappears, it tells you that there is leak in the building. When the leak is found and repaired, the cause of the efflorescence problem is removed.
For technical services, please call Combocrete International Products Company at (852) 2869 0228.