Unstable windshield crackout during repair.

[screenman]

You had a damage run on you for a reason you do not know, this has never happened to me in 23 years, just trying to understand why it it did so.

Sure I have had some go but always due to me doing something wrong, recognising why or how it might go prevents it from going in my opinion.

I will keep an eye out for your posts and try not to answer them in future if that suits you best.

[t4k]

Sure I have had some go but always due to me doing something wrong, recognizing why or how it might go prevents it from going in my opinion.

What exactly did you do wrong to cause them to go?

[screenman]

t4k in answer to your question.

Did not cool the glass down.
Put bridge on with injector screwed out.
Flexed legs to hard when I was not looking from the correct angle to see what was happening.
Over heated with drystar.
One I remember back in 1988 a VW that was a nice bullseye and for some reason I got inside and pushed it to see what would happen.

These are all things I did wrong because I was stupidly not paying attention to detail, but as soon as the break run I knew what I had done wrong.

[DryStar]

Mr Bill,

I know how you feel having a crack out while trying to do everything right. Unless it's a common experience I wouldn't sweat it, just move on to the next one.

In my 16 year stretch with glass repair and replacement I've ran into these UCO's (unidentified crack outs). 90% of the time they can be explained but 10% of them have never. We are working with glass and when fractured it can become very unstable. That's the nature of this business.

I've work on repairs before under ideal conditions and had them run by just placing the bridge on glass. I also had a customer once that went into her glove box for insurance card and upon closing her door that little star traveled 20 inches across shield. (which I never touched but got blamed for) Stuff happens!

[Nomad]

Exactly right Drystar.

A friend laid his hand on the roof of a pickup to lean over for a look and the break split the whole ws in two. Had a chip I was working on that everything was going well with, turned around to pick something up and heard a kind of thump, it had split from top to bottom. Applied a suction cup to the inside of the ws and a crack ran six inches.

I haven't tried this but if putting pressure on the outside causes the chip or crack to run, put a crack expander on the inside right under where the injector presses on the glass. It seems to me that usually the sensitivity is only on one side, so placing something on the back side wouldn't disturb anything. But I would watch closely what is happening. If you balance the force of the injector with an opposing force on the inside it would seem to me to help the situation a lot.

I think what was done was correct. I have had this happen to me and what I have done is to cure the resin in the center in order to stabilize things. Then drill and fill from the outside. That's what makes this business interesting, just about the time you think you've seen it all, you run into something new. The thing is not to panic and make things worse, but to evaluate what you've done and see how things can be made right. Most times they can, sometimes not!!!

[DryStar]

Just another tip from past experience.

In early spring when outside temps are still low, glass will feel OK from outer layer but if your working on a vehicle with black or dark interior on a sunny day, interior layer of glass could be 30-60 degrees warmer. That extra inside temp will stress outer layer of shield. Best to always open windows and allow both layers to equalize.