ABSTRACT

Feathery or fluffy efflorescence should be allowed to dry out before removal with a bristle brush; even if glossy and encrusted it is often possible to eradicate by scraping when it is not strongly keyed, first softening the deposits and then discarding them before washing the surface with water. This should preferably be carried out by men skilled in the procedure and with a knowledge of local conditions. If some of the salts soak back into the wall and re-appear, the same techniques should be adopted until their movement ceases or they at least become acceptable. Continued physical treatment, vigorous or otherwise, demands sensitive workmanship to avoid damage, and restoration of important buildings should only be undertaken by specialist firms. Before dealing with an extensive outbreak of efflorescence, it is advisable to consider the effect of cleaning a small section which may show up another. It is better to leave certain areas until the concrete is, say, a month old to let nature take its course. In any case, little can be done to remove hydration discoloration which is a more deep-seated contrast in shade.