Are you working in a vacuum?
September 1, 2007
As a windshield repair technician, it is vital you understand how to remove air from a break and why it is important to do so, as well as the merits of different air-removal methods.
The ANSI Repair of Laminated Automotive Glass Standard, ANSI/NGA R1.1-2007, states repair technicians must “remove the air from the break, either by vacuum or displacement.” By removing all of the air from the damage, you make room for the resin and ensure a better-looking, stronger end result. However, this is not as easy as it sounds. A stone chip, for example, may have an impact point, a cone of glass that separates from the main piece of glass and small cracks or legs radiating out from the main body of the break. You must completely evacuate the trapped air from all of these areas, and this can be especially difficult in tight spots.
The two basic types of repair systems are those that utilize vacuum and those that do not. Systems commonly referred to as “screw thread-type injector systems” do not create much vacuum and rely on the pressure from injecting the resin to displace the air in the damage.
Systems that utilize vacuum as part of the repair process fall into two categories: those that use an external vacuum source such as an electrical or mechanical vacuum pump, and those that create a vacuum within the injector itself. Injector vacuum systems utilize a strong vacuum to pull the air out of the break. It is important these systems generate a high enough vacuum—usually at least 20” Hg—to overcome the surface tension of the resin that may be trapping the air in the break. It is also important that you give the injector enough time during the vacuum and pressure cycles to ensure you’ve removed all of the air and completely filled the damage with resin.
No matter what system you choose, closely follow the manufacturer’s procedures to operate it efficiently and produce the best repairs possible.
Using appropriate procedures to complete repairs is just a small part of the big picture. As glass repair professionals, we are responsible for the state of our industry. In order for the industry to grow, improve and reinforce its legitimacy, we must stay up-to-date on current science, technology and techniques. Research the latest technologies, and embrace the improvements that become available. The new ANSI ROLAG standard is a good place to start in this regard. To view or download the standard, visit www.rolags.com.