Masonry Magazine May 2008 Page. 24
CLEANING
We focus on minimum time and getting a very effective clean, Weil says, noting that the hydrochloric acid-based chemicals used by masons for cleaning are much more active in hot water than in water at an ambient temperature. He estimates that masons using his piece of equipment can complete a job in one-third the time it would take with a more traditional method, such as a bucket and brush. In addition, using Kem-O-Kleen takes about half the time to finish a cleaning job versus using a pressure washer and applying the chemicals with a brush or Hudson sprayer before the final rinse.
When you wet the wall down, it immediately begins to cool before you can even get the chemical on the wall," he says, noting that the hot water pressure washer not only saturates the brick, it also heats it, preparing it for the chemicals about to be added into the stream without any delay in between steps.
From a process consistency perspective, Kem-O-Kleen's needle valve precisely measures chemicals into the water stream at a ratio of about 10-to-one. Traditional methods often apply chemicals onto the masonry more heavily in some spots than others, and can cause excess chemicals to run down the bricks.
So what about potential damage to masonry with such a high psi? "That's at the nozzle," explains Weil. "We recommend
16 to 18 inches between the nozzle and the wall, so there isn't 3,000 psi hitting the wall, and it doesn't blow out joints. If you have a more sensitive brick, you can adjust the pressure or just stand back farther."
Maintenance of the equipment is easy, says Weil, adding that chemicals can be left in the 20-gallon on-board tank between jobs, but not when stored away for the winter, for example. "It cleans up after itself," he adds.
If such equipment is to be stored for a number of months, however, he recommends flushing the equipment with windshield-washing fluid or antifreeze. In addition, the use of this machine and similar equipment doesn't allow for the reuse of chemicals, so a quality result can be expected every time.
To use Kem-O-Kleen for maintenance cleaning or restoration work requires a separate nozzle assembly for the wand, which enables the user to apply the chemicals and allow them to dwell for a short time before rinsing.
Robert Port, VP of engineering for Restoration Direct, says the secret to cleaning buildings is not so much washing it off, but using equipment designed to apply chemicals without overspray or penetration.
"If I put chemicals on the wall to clean, like it or not, the dirt is on the surface, not one-quarter of an inch in," Port
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www.trowandholden.com
Above A technician cleans concrete brick. Note that the cleaning procedure for masonry starts at the bottom and works up. This is to keep rundown from soaking Into, and staining dry masonry. Masonry below the area being cleaned always needs to be kept wet so that rundown won't soak in.