Masonry Magazine April 2001 Page. 18
BLOK-FLASH
The complete flashing system for single wythe C.M.U construction.
ADVANCED
BUILDING
PRODUCTS INC.
P.O. Box 98, Springvale, Maine 04083
Tel: 1-800-252-2306 or (207) 490-2306 Fax: (207) 490-2998
www.advancedbldgproducts.com
www.blok-flash.com
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asked to view the sample and judge the quality of finish. In many cases, architects look to contractors as experts and appreciate good advice and proven results.
In some cases, the specification will not only identify the chemical to be used, but also the application process. Chemical manufacturers may do this to protect themselves from liability. As a result, some encourage use of the most timid application process as a protection from the results of poor workmanship. The suggested process may also result in use of the highest quantity of chemical and the longest completion time. Even with the most basically trained workers, cleaning can be done safely and without incident if the right combination of equipment and chemicals is used. When doing recommended testing on a mock wall, it is beneficial not only to use the application process recommended by the manufacturers of the different chemicals, but an application process proven by knowledge and experience. Again, proven and demonstrated contractor expertise is appreciated and respected by an architect whose goal is a quality finish.
Responsibility for selecting the proper chemical for cleaning is an important obligation that benefits from input not only from the chemical supplier and the architect, but the masonry contractor. The contractor has the practical experience to influence the decision-making process and the practical responsibility to recommend the proper chemical.
With a well-selected worker using the proper chemical, the final element to ensure excellent cleaning can be considered: the cleaning equipment. Available equipment ranges broadly, from buckets, brushes, scrapers, and burlap bags to high-pressure washers specifically designed for cleaning masonry. The selection of proper equipment is a function of how much cleaning is to be done, the time available to complete the work, and the capabilities of the equipment.
The initial and basic function accomplished by all equipment, from the simplest to the most specialized, is thorough wetting of the masonry surface in preparation for the application of cleaning chemicals. Whether a brush is used to create friction and heat or a hot water washer is used, heating both the wall and chemical increases cleaning efficiency and reduces overall chemical usage. Typically, for every 35°F of temperature increase, the cleaning power of the chemical is doubled. Any experienced cleaner knows cleaning proceeds faster in warm weather than cold, though the reason for this may not be understood. In addition to readying a wall for application of chemical, once the cleaning is accomplished, the wall must be rinsed well. Again, in the final rinse, hot water is useful to dry the wall quickly and reduce the absorption of chemical and water into the masonry that can cause efflorescence.
Though there are numerous companies making pressure washers, there is little choice to achieve a cost-effective, quality result in cleaning masonry. Companies around the country manufacture very similar standard washers that are usually used for general cleaning. However, a specialized washer with an acid handling system is especially suited to cleaning masonry. While standard washers have the ability to handle detergents, they do not tolerate the harsh chemicals used in cleaning masonry. Using a standard washer to apply acid-based chemicals wears metal parts and creates high-pressure leaks. High maintenance costs result and, over the life of the washer,