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Cracking Glass in the heat!?!?

Posted: June 16th, 2016, 11:07 am
by Simplysalted
Hi! New here. Been doing Glass repair for going on 2 years now. I serve multiple accounts and customers. This last week it had been very Hot! 95+ and I've had 2 windshields crack on me while working on me.

I've cooled the glass, then covered it , put the injector on with very light pressure. After a few min the rock chip turns into a crack and replacement is required. Speaking to the older guys at my company , I'm being told to open up the cars and let them cool down more.

Just thought I'd get as many ideas as possible on what I could do to prevent this. Thanks!!

Re: Cracking Glass in the heat!?!?

Posted: June 17th, 2016, 10:41 pm
by screenman
If it is too hot to put your hand on it is too hot to work on. That is the line that I tell my students and it seems to work quite well.

Re: Cracking Glass in the heat!?!?

Posted: June 18th, 2016, 8:42 am
by Brent Deines
If possible I always try to move the car into the shade. If that is not possible I cover the windshield with a hood protector. Some technicians shy away from hot weather repairs but personally I prefer hot over cold or wet any day, you just have to take a few extra precautions.

If the car has been sitting for awhile and I have access to the keys I leave the windows up, start the car, turn the A/C on high, and turn on the defrosters. At first hot air will blow on the windshield but it will gradually turn warm, then cool, then cold, thereby gradually cooling the inside of the windshield. If the car has been running and is already cool inside I still use the defrosters but try to match the temperature of the air being diverted to the windshield to the inside temperature of the glass, then lower the air temperature slightly every few minutes until the desired glass temperature is reached so I'm not blowing cold air on hot glass This is a controversial technique but one I have been using successfully for nearly 30 years. If you cannot start the car then opening the doors or windows is your next best option for lowering the temperature inside the car but that will not lower the temperature of the glass very quickly.

How did you cool the glass before you covered it?

What did you cover it with?

Other things to consider:

Be sure your resin is not too cold. I can tell you from experience, cold resin on hot glass is a recipe for disaster.

Use minimal pressure against the glass when mounting your bridge and adjusting your injector. This is always good advise but especially in extreme weather conditions, hot or cold.

Re: Cracking Glass in the heat!?!?

Posted: June 20th, 2016, 5:46 am
by Simplysalted
The way I cooled the glass was using a wet towel. I wipe down the glass till the towel gets hot, shake it out, then repeat till cool.

I believe my mistake was not opening up the car. While I cooled the glass on the outside, the inside was still hot and building pressure.

Re: Cracking Glass in the heat!?!?

Posted: June 20th, 2016, 11:52 am
by screenman
Therein lays your problem, the heat in the inside glass is causing it to expand whilst the cool outer glass is trying to contract. Now cool inner glass will and warm outer glass is way less likely to cause a crack out.

Of course the other thing to look out for on a hot day is a surface leg, boy can they run fast.

Re: Cracking Glass in the heat!?!?

Posted: June 28th, 2016, 6:01 pm
by the big welshman
Has anybody tried on aVERY HOT day small half moons and small 1/4 crack drill were the stone hits the windshield or at the end of the chip ie the dark area put some resin around the area were you have drilled and then cover the chip with black electrical plastic tape, leave it for a while 5/10 mins remove the tape the chip has disappeared then pit filler resin plastic tape the area and remove with a razor :mrgreen: :mrgreen: :mrgreen: :mrgreen: :mrgreen: :mrgreen: