Combination break runs out to crack

[Gedis]

Hi, I am new into this business, and today in the field I had one big problem. I had a combination break with lots of legs in a diameter of around over an inch. I had to use my moisture evaporator from delta to get the moisture out. Few seconds into the process, the star breaks out into a long a$$ crack around 6'' to 7'' one way and to the edge the other way. The star itself was within 3'' from the edge. What could be the reason for the break??? Thanks

[Sikandar]

Sounds like too much heat!

Overheating the windscreen will cause the glass to expand which in turn will encourage the crack to run!

[GlassStarz]

evaporators use heat I tend to stay away from heat unless the moisutre is obvios, as you stated you are new and crack outs are an unfortunate part of the learning curve after a few you will learn to recognise what is fragile and needs tlc

[Brent Deines]

Moisture evaporators produce a very intense heat, 212 degrees to be exact, which is why there are several precautions that need to be taken when using this tool.

1. The tool should never be used on cold glass. Always slowly warm the area for about 6" around the glass prior to using the tool to dry out the break. The moisture evaporator works well for the warming process, just be sure to keep it moving during the warming process.

2. When you do begin the dry out process, be sure to follow the instructions carefully. The tool should be preheated and placed over the center of the impact point for 20 seconds only. If a second heat application is necessary, which is rare, be sure the glass is allowed to cool to the touch before proceeding.

I have never witnessed, or even heard a complaint about the moisture evaporator cracking out a break when used properly, but crack outs do happen occasionally, even when a moisture evaporator is not used, and breaks near the edge of the glass are more likely to crack out than breaks in the center of the glass.

The most common reason for crack outs is excessive pressure, but the second most most common reason for crack outs is a rapid temperature change, which is why the glass needs to be warm prior to using the moisture evaporator. The unique thing about the moisture evaporator however is that although it heats the outer layer of glass very quickly, the laminate and the inner layer of glass do not get nearly as hot as when other heating methods are used due to the 20 second limitation, the fact that all the heating is done from the exterior of the vehicle, and because the small area that is heated cools quickly after the tool is removed.

In 20 years of repairing glass I have only experienced two crack outs personally. One was when giving a demo to a bunch of glass shops when the glass temperature was about 150 degrees and I injected resin that was about 65 degrees. Talk about embarrassing! The other was when the glass temperature was about 40 degrees and I injected resin that was about 80 degrees. I was doing this repair for an insurance agent that sent me a ton of business, so again, I was very embarrassed. In both cases the problem could have been avoided if I had taken the time to properly adjust the glass and resin temperature. Fortunately, in both cases the customers were very understanding, although I did have to endure years of good natured ribbing.

Feel free to give me a call if you would like to discuss this issue at greater length. I would be very interested in hearing the exact details surrounding this unusual event. I know what a terrible feeling I got in the pit of my stomach when my crack outs happened, so I want to make sure you are doing everything possible to ensure it doesn't happen again. 800-548-8332 x304

[GGWSR]

Brent...in the 3rd paragraph of your thread you mentioned "other heating methods" what methods are you refering to...thanx

[Brent Deines]

Other heating methods include heat guns, torches, heat lamps, forced air heaters, blow dryers, cigarette lighters, etc.

Other than moisture evaporators, only heat guns and torches produce enough heat to dry out a break in a reasonable amount of time. It is not only very difficult to control the amount of heat produced, but limiting the area to be heated also presents a challenge.

The other methods mentioned that produce lower temperatures are fine for warming the glass, but are not effective for removing moisture.

Using anything to heat from the inside gets the inner layer of glass and the laminate much hotter than the outer layer of glass, which is not only unnecessary but counter productive. I should clarify that I believe warming from the inside is fine in some cases, although much less efficient than warming from the outside, but heating from the inside for the purpose of moisture evaporation is never a good idea.

[screenman]

Personaly I do not warm up such a large area, I use a blow torch most of the time and go straight into the break working from the outside into the center keeping the heated area as small as possible. If a crack does run it wiil stop as soon as it hits the cooler glass. So the smaller the heated area the smaller the crack. Also the less volume heated the quicker it will cool down. We train all our techs this way and have no problems with crack outs.

[Gedis]

When it comes to the temp of the w/s, the weather yesterday was around 95+ degrees and no shade. Glass was pretty worm, but I guess what I did wrong is I did go for the impacted area right away. I wasn't only sweating my b__s of from the weather, but most part for that crack out. Another thing was that this was my new dealership that I was trying to get an account. I can say that I did get that account and will be getting more business from them.

[mrchip]

why did you think there was moisture in the glass???if it was 95+ in direct sun ..glass should be pretty hot..moisture??..any more particulars??

[Gedis]

it was raining couple hours before and the first repair that I did few min before did have moisture inside.