Masonry Magazine July 2004 Page. 21
Perhaps nothing is more frustrating for a contractor than to lose or shut down a job because of what is perceived to be ineffective chemistry.
Captions for Cleaning Photos (clockwise from opposite page:
This shot shows two test panels done on a building in Washington, D.C. The left sample did a much better job than the one on the right. The real story, however, was that the testing uncovered deep oil stains beneath the windows that were covered by the dirt. Although the product used on the left sample cleaned the primary surface extremely well during the initial tests, in subsequent tests the contractor decided to use another product that more effectively cleaned both the surface and the oil stains.
White "scum" on brick that was created by a cleaning chemical. It can easily be confused with efflorescence, and a few simple tests can help determine the right solution.
Close-up of efflorescence on block wall.
YOU'VE GOT A GOOD CHANCE AT A BIG JOB.
All that's left is to complete a "cookie cutter" demonstration like you've done many times before using your normal cleaner and process. This time, though, it's not working, and you don't know why. The job is lost, and the only option is to call the chemical manufacturer and complain about their product not working.
Perhaps nothing is more frustrating for a contractor than to lose or shut down a job because of what is perceived to be ineffective chemistry. Yet, more often than not, the problem isn't with the chemical itself. Rather, the issue is usually associated with using the wrong chemistry to solve the problem or the chemical's performance being hampered by any one of a number of variable conditions. It may even be a case of an inappropriate chemical being specified by the substrate manufacturer.
The answer to avoiding a situation like this is simple: testing. Testing is usually done on major projects but can be overlooked, particularly on small- or medium-sized ones. Testing is important because identifying the right solution can be a complex process since a variety of factors can create a virtually unlimited number of potential problems (see sidebar on page 20).
In some cases, you may need multiple solutions to correct a problem. A good example is our process for removing calcite. Generally, we recommend spot treating with calcite remover followed by an application of our new masonry detergent. The calcite remover softens the calcite while the masonry detergent removes it completely and ensures that the face of the substrate will appear uniform and without streaks.
In addition, on projects where a color sensitive substrate or mortar is being cleaned and color bleed may be a concern, we recommend using another mildly acidic soap solution instead of the new masonry detergent in order to achieve the surface uniformity while protecting against color bleed.
In this instance, if you were to clean the building only with the calcite remover or new masonry detergent, chances are you would be unhappy with the results. More than likely, this would mean a phone call to the manufacturer complaining that the product didn't provide the desired finish when, in fact, the product did exactly what it was supposed to do.
Another common problem is misdiagnosing a stain, which we often see with efflorescence. For example, recently we received a call from a contractor who said his company was having trouble removing efflorescence from a brick wall. Since the job site was nearby, I decided to do an onsite inspection and test. After several unsuccessful
The Voice of the Mason Contractor
July 2004
Masonry 19