When is it Too Hot?

A few years ago, I was asked to judge an auto glass installation competition at a large western glass company. That company planned on having the competition at a race track in their area so spectators would be able to watch. The temperature that day was going to exceed 100°F and the vehicles were parked outside in full sunlight.

When the judges arrived, we checked the adhesive instructions which stated that the application temperature should not exceed 110°F. Obviously, we were concerned about the high temperatures surrounding the competition. However, when the instructions said “application temperature” did they mean product temperature, surface temperature or ambient temperature?  What would be the ramifications of applying the adhesive in extreme temperatures?

We had an adhesive representative who was present for the competition, so we asked him for advice. Unfortunately, he did not know the exact answer, and due to the fact that the competition was occurring on a weekend, we were unable to contact a technical advisor at the adhesive company’s technical lab.

Through some serious discussion between the replacement company owner, the adhesive representative and the judges, we decided to take steps to cool down everything involved with the installation. We placed the glass and adhesives into air-conditioned service vehicles to make sure that the glass surface and the adhesives were well under the temperature limit of 110°F. We also started the vehicles and ran the air-conditioning in advance of the competition to assure that the vehicle was cooled down before the competition proceeded. We weren’t sure at the time what the upper temperature limit of the “Application Temperature” meant, but we were certainly not going to install glass under conditions contraindicated by the sealant manufacturers.

Since that incident occurred, I have researched this issue and found that there are different consequences for applying adhesives beyond their temperature limits. They can include bonding deficiencies, application problems and storage concerns. Obviously, the most important of these consequences is the bonding problem. If the sealant does not bond properly, the result could be injury or death caused by improper glass performance in a crash.

If the adhesive loses its viscosity, the adhesive pre-maturely cures, and waste is the obvious result. If the adhesive loses its thickness due to higher than normal temperatures, it can drip onto the customer’s interior causing vehicle damage. Under extreme heat conditions, the weight of the glass can flatten the windshield to the pinchweld’s metal and cause a stress fracture. Lastly, if sealants are stored improperly, the product cannot be expected to be to perform as promised.

The moral of the story and the research we conducted says one thing, temperature matters and caution must be exercised to insure proper performance of your adhesive products. Check your adhesive’s technical data and installation instructions for temperature limitations.  If for some reason the data is missing or not clear, check with your adhesive rep. If the rep is unsure, check with the adhesive company’s technical expert for clarity. This is important. It is not enough to go through the procedures perfectly if you don’t know your products limitations. Do it right every time and think before you proceed.