Star Runner!

[screenman]

Hair dryer heats up too large an area for my liking, as we have to wait for the glass to cool to the ambient temperature before starting the repair. When drying out I like to keep the heat a small as the chip itself. The more glass you heat the longer it will take to cool.

The lower the air pressure the lower the evaporating point of water, hence the vaccum pump. However when we place a vaccuum pump over a chip we make a closed vessel, in other words the chip and pump become one, so can anyone explain why the moisture should go into the pump end rather than stay in the chip end.

Hot glass as we know is far more fragile than cool glass, hence when we overheat a damage to dry it and it cracks, the crack normally stops once it hits a signicantly cooler area of glass, another reason to keep the dryout area smaller.

[Brent Deines]

I use a hair dryer to warm but not to dry out. If the glass is cool I warm up a large area around the chip with a hair dryer before heating with the moisture evaporator to dry the damage. This way there is not such a drastic change in temperature in the 20 seconds that the moisture evaporator is applied. However, as screenman said, keeping the area that is being super heated to remove moisture as small as possible helps eliminate crack outs. The new heat exchanger tool will also help as it pulls the heat from the glass very quickly, however the same rules apply. I would not put anything too cold on a hot windshield or too hot on a cold windhshield. Warming should be gradual.

Technicians sometimes use the vacuum tools (brake bleeders) to remove moisture but I've never found them to be very effective. Some will also use them to lower the pressure in the break as the damage is heated, but that means you need to heat from the inside of the glass so far more heat is required. I believe that defeats the purpose of lowering the pressure in the break. You would not want to use a vacuum pump to remove loose glass fragments as it could damage the pump.

Maybe the star you were working on broke out because of the dry out process, or maybe it was just a volatile crack and would have broken out anyway. I mention this because I have brought cars into my shop in the winter so they would warm up prior to repairing the glass and watched the cracks grow without me every touching them. I have also had a crack grow significantly as I injected the resin for no apparent reason. I’m happy to report these instances for me have been few and far between, but that doesn’t mean you don’t want to hurl every time it happens.

[Crack Attack]

Korey Ill take two of them.

James

[Kgobin]

I have emailed you so please email me back or call into Delta Kits. Currently, I am at the Glass Build America Expo but either way we can get your order processed and shipped tomorrow.