Masonry Magazine June 2007 Page. 26
NEW RULES FOR CLEANING
While these various masonry materials often are created to look similar, each has widely different tolerances for cleaner strength and pressure washer psi.
The good news is that by following a few simple guidelines, you can produce great results every time on even the most complicated combinations of concrete, clay and stone masonry-natural and simulated.
Some of those well-known guidelines, like "always test before cleaning overall," are timeless; while others, like "clean early and quickly," are becoming even more increasingly important.
For masons taught in the traditions of "masonry equals brick or block," and "one-size-fits-all" cleaning, new rules such as "know your surface"- need to be stressed.
The New Rules
# 1. Know Your Surface
IN 2003, a knowledgeable and professional contractor cleaned a two-story brick office building in Indiana. He used a proprietary product from a reputable manufacturer and followed responsible procedures, just as he always did.
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The cleaner was appropriate for clay brick; however, the contractor didn't test it before using it on this simulated stone. Along with the excess mortar and job dirt, the cleaner removed most of the stone's surface-applied color.
Too late, the contractor discovered he was cleaning concrete brick, not clay brick. The powerful cleaner, though safe for clay brick, pitted and bleached the concrete. The contractor landed in court.
Concrete brick and simulated stone often look like clay brick and natural stone - that's the idea. While these various masonry materials often are created to look similar, each has widely different tolerances for cleaner strength and pressure washer psi.
Also, cleaners for concrete masonry often contain non-etching ingredients not used in the cleaning products for clay masonry. The small amounts of acid(s) found in cleaners for clay and concrete are usually different as well, specialized for each particular substrate.
While it would be wonderful to simply determine the material type, even individual types of clay brick or natural stone have important differences. Some clay bricks have special additives that create striking color effects, an inappropriate cleaner can react with those additives, causing hard-to-remove stains. For example, cleaning limestone or cast stone the same way you clean granite or sandstone can cause etching or bleaching on the substrate.
Know your surface! As soon as you get the job, get on site and positively identify every substrate you'll be cleaning.
# 2. Always Test Before Overall Cleaning
WHEN Sparkle Wash International contractor Craig Christensen of Omaha, Neb, cleaned the simulated river stone exterior of Cabela's, Omaha, he followed rule number one. Christensen got on the job site as soon as he could to examine the rounded, multi-colored concrete stones.
He received samples from the mason contractor and took them back to his shop. The simulated stone used on the project came in eight colors, and Christensen tested cleaners on each one. He found that six of the stones were integrally colored and could stand up to a vigorous cleaning with the right product However, the other two sported a cementitious surface coating to give them their color. The cleaning technique that worked on the six integrally colored stones bleached the other two.