Water Exiting Crack While Heating!

[GLASSTIME]

I was repairing a crack just the other day. After a few moments of heating the windshield I applied my Hair Dryer to warm the outside of the glass. After my HD was in motion for at least several minutes My client and I noticed Water Exiting the crack outside and of course dripping down the crack.

Didnt know if any of you have experianced this before , I am guessing due to the heat which caused the craxck to expand or open up releasing moisture!

Might I add this crack was awesome when completed.... Id say my best thus far! Pat on the back!

[GlassStarz]

When you heated the glass it expanded and closed the crack forcing the water out

[Mr Bill]

I always use the drystar to remove moisture before attempting the repair.
I was wondering how many of you apply heat to the inside of the windshield behind the repair to help resin to flow.
Do you do it all of the time or just as a last resort?
How does it affect your repairs?

[David T]

Time2Shine,
You have brought up a VERY good point. As Brent and Korey have educated me, temperature is a vital aspect in providing a quality repair.
In my limited experience (in an environment that has nearly 100% humidity year round), the temperature of the exterior laminate of a windshield is a crucial factor when using a moisture evaporator.
In my experience, well over 50% of the repairs I have done using a moisture evaporator (WITHOUT sufficiently warming the windshield first) resulted in crack outs.
It is very "interesting" to have a customer stand over your shoulder while they watch a repair being done and they see (and sometimes hear) a crack run out while using a moisture evaporator.
In fact, they sometimes have no hesitation in pointing out that they have agreed to pay you to fix the damaged area,not create additional damage.
Fortunately, the quality of the repairs (along with a money back guarantee I offer) that the Delta Kits equipment delivers, has made this pretty much a non-issue.
It seems like most WSR techs in other areas of the country do not have a problem in regard to this matter.
As for me, I carry a 110v hair drier and a 100' extension cord and SLOWLY warm a windshield (even during the Summer) before using a moisture evaporator. After using a moisture evaporator, I allow about 10 minutes for the windshield to cool enough before continuing with the repair (not much of an inconvenience if I take the time to casually attach the bridge or talk to the customer about their car).
Since this has been an issue in my repairs and there hasn't been all that much discussion about it, I look forward to learning from other WSR techs that have more experience than I.
David

[screenman]

Careful with that inside heat as too much will cause the damage to shut, this to the untrained eye can look like the damage has filled. Also if you think of the mechanics of the glass, it takes a while for the heat to transfer through the PVB so it is possible to have warm/hot glass inside and cold oustide one expanding at a different rate to the other and causing spread out. I will try and explain this better, as the inside glass expands it pushes outwards, onto the cooler unexpanded glass, now this will react like when you bend say a plastic sheet the outside will split before the inside. Bit of an extreme example, this is the reason cold screens with damage tend to split when the temperature in the car get hot fast. I am not saying do not keep the glass warm just saying be careful.

Warm or hot glass as we know is far more fragile than cold glass, this is why I like to use heat sparingly. I work a lot on trucks and buses and I use the Drystar or the micro torch, these sort of vehicles do not give one the benefit of being able to warm the windshield, however I have only twice had crack outs in the last few years using one of these heat sources and in both cases it was my fault, I left it on too long.

[Brent Deines]

When heat is necessary I heat from the outside when possible, or from both the inside and the outside at the same time. I also try to heat up as much of the windshield as I can, and never less than several inches around the damaged area. I agree with screenman that too much heat can cause cracks to temporarily close, and heating from the inside only requires far more heat than heating from the outside for the same effect.