Masonry Magazine July 2004 Page. 22
CLEANING
A solution that may be effective on the East Coast may not work well on the West Coast or vice versa due to climate differences.
After attempts to remove the efflorescence, I finally realized that what we were trying to remove wasn't efflorescence but a much harder deposit commonly referred to as "white scum." We then switched to a product that we knew was more effective at softening the harder deposit and resolved the problem.
Again, in situations like this, we are likely to get a call complaining that the chemistry isn't working. In reality, the problem wasn't bad chemistry, it was just a case of a wrong diagnosis. These two compounds, while looking similar, are actually quite different chemical compounds and require different chemical solutions to dissolve those compounds. As this example shows, testing can be a great way to properly diagnose a problem.
Testing can also help determine important information like the best dilution rate for a particular situation. Recently, on a trip to the West Coast, I visited a school site in Washington
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INFLUENCING A CHEMICAL'S EFFECTIVENESS
Testing is a means for evaluating the impact of a number of conditions that all play a critical role in determining the effectiveness of any chemical's ability to lift and remove a stain. Without adequately assessing each of these factors, the potential for problems or worse, failure -is much greater. Among these factors are:
* The intensity of the stain and how deeply it has penetrated the substrate
* The type of substrate itself and its porosity,
* The condition of the substrate (Was it cleaned previously? Is the surface burned? Was it sealed?)
* Dwell times:
* The dilution levels of the chemical;
* The geographical region and climate:
* The weather conditions (temperature, humidity, etc.) on the day the cleaning will take place; and
* The application process itself (Le. brushing vs. spraying).
whose contractor had run into a problem with an anti-graffiti coating. Apparently, the brick exterior was still retaining moisture from rainfall several days earlier. Due to the moisture, the anti-graffiti coating wasn't being fully absorbed into the brick, and the excess was drying in several spots as an unsightly white haze.
After testing several products and dilutions, the contractor arrived at a solution that removed only the excess coat-
These test panels on a school building in Tigard, Ore, were testing a variety of products and dilution rates on their effectiveness at stripping excess anti-graffiti coating, while at the sam time stil retaining enough of the water-repellant characteristics to satisfy the manufacturer's warranty. After the chemical tests were completed, a RILEM test was performed on each pane to determine how much of the sealant was retained.