Page 185 - Masonry and Concrete

Masonry Construction Techniques
184 CHAPTER FIVE

FIGURE 5-36
Calcium carbonate stains or “lime run.” (from Beall, Christine, Masonry Design and
Detailing, 4th edition, McGraw-Hill, New York).

ever, will eliminate the mechanism needed to form the liquid solution
and carry it to the masonry surface.
Before calcium carbonate stains can be removed, the source of
moisture must be located and stopped. Once that is done, the stain and
surrounding area should be saturated with water, and a dilute solution
of one part muriatic acid to nine parts water applied. Using a stiff
fiber-bristle brush, the stain can be scrubbed away and the wall thor-
oughly rinsed with water to remove the acid and residue.

5.9 Clear Water Repellents

Water-repellent coatings are often applied on architectural concrete
block and on some light-colored stone, but their effectiveness is usu-
ally limited to a period of three to seven years, depending on the prod-
uct selected. Water-repellent coatings can be applied in one of three
ways, depending on the size of the surface being treated:

■ With a synthetic bristle paint brush
■ With a synthetic roller and plastic paint roller pan

■ With low-pressure (20-psi) spray equipment with a stainless
steel fan tip nozzle.

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