News to know
Fabrication debris common in heat-treated process
This is the second story about cleaning glass with metal scrapers. A longer story will appear in an upcoming issue of Glass Magazine.
The demand for heat-treated glass has increased during the past decade due to the development of higher-performance tinted and coated glasses that must be heat-treated to avoid thermal stress breakage. Higher design loads require stronger, heat-treated glass to prevent breakage. According to members of the glass industry, a clean product is delivered to the job site, however, microscopic fabrication debris might be on the glass surface and is essentially undetectable until hit with a scraper.
Meanwhile, window cleaners continue to clean glass with metal scrapers -- the same way they have for the past 40 years or more. Many window cleaners believe the debris on the glass is a result of poor fabricating procedures. Glass fabricators clean and maintain the glass washers and tempering equipment, but this does not prevent the random occurrence of surface particles on heat-treated glass, according to experts in the glass industry.
It’s quite a predicament for two industries involved in different ends of the construction process. The glass manufacturers and fabricators produce high performance coated glasses that assist in safety, energy savings, human comfort and the attractiveness of a building. Before the ribbon can be cut, the window cleaners are called in to do their job.
“Scrapers are a standard technique for construction window cleaning,” says Dan Fields, president and CEO of Fields Construction Services, Livermore, Calif., the West Coast distributor of SRP Scratch Restoration Systems. “All construction window cleaners use blades and scrapers, which will not scratch glass. All scratches come from defects on the glass.”
Fields’ name is prominent on both the Web sites for the International Window Cleaners Association, Kansas City, Mo., and the Association of United Window Cleaners, Milwaukee. He flies across the country to present seminars and supply expert testimony about defects in glass.
“The only heat-treated glass that scratches with ‘metal’ scrapers has excess fabricating debris on the surface as a result of poor fabricating procedures,” he says.
Many washers today include a pre-spray area that removes debris even before it enters the washer, says Bob Lang, sales engineer, Billco Manufacturing Inc., Zelienople, Pa. The company makes and sells machines that wash glass.
However, no equipment upgrade, cleaning or maintenance can eliminate the occurrence of fabricating debris because of the nature of the process, according to those in the glass industry. The large volumes of air used in the quench can create airborne particles, the glass seaming operation creates particles and the occurrence of glass breakage in the tempering oven all serve as a source of microscopic glass particles that will periodically end up in the oven or on the glass and become stuck to the surface of heat-treated glass.
A Canadian company has discovered an alternative to scrapers.
City View Maintenance of Vancouver has been cleaning windows without scrapers since January. Rejean De Guise, who owns the company along with Howard Schuk, says the process involves powders and a paint-thinning product.
“Each time I introduce myself, and tell them [potential clients] I don’t use razor blades, they are [thrilled] out of their mind,” Guise says. “I use the expression new technology.”
Guise says he is planning to expand his company since it is booking about twice as much business as in the previous year.
“We’re not using blades, and it’s such a relief,” Guise says.
To read last week's article, click here.
--By Matt Slovick, editor in chief, Glass Magazine