Windshield Repair Forum

Why did you use the spring hammer to open the damage rather than drilling ?

Puka Pau

Last week, I had a problem with a repair. The damage was a 5 leg "Star" on a VW Golf, approximately 4" from the " A " post edge on the drivers side. Everything seemed fine, all the legs were flexing, glass temperature was good, but as soon as I applied my repair equipment, a crack shot straight to the edge of the screen!. I was able to repair the damage successfully, but what puzzled me was the speed at which the crack happened. When I got home I did some research on windscreen manufacture, focussing on stress problems. During the process the edge of a laminated screen must be cooled quicker than the rest of the screen to give it "Edge Compression", this essentially seals the stresses within the glass, preventing premature cracking during manufacture and fitting, something that is known within the business as "Stress Cracking". If the cooling process is faulty it leaves intermittent stress gaps at the edge of the glass which will allow any tensile stress to cause a break very easily. I think this was the cause of the rapid break out. Unfortunately there are no visible indicators, prior to repairing, of this weakness in the glass. The only advice I can give is to be wary of this happening with a Star break, close to an edge where there has been a high degree of curvature( bending) done to the glass during manufacture. This will usually be along the "A" post edges.

This is a post I did a while ago, it might help to explain some cracking issues.

Sorry made a mistake. I din't use the Spring Hammer to open the break, I DID use the dremel... LOL
I used the Hammer to clean it out! Sorry once again for the mistake.

Did I understand correctly that you were using the defroster in the car?

Just a thought??/

Wonder if you could just "Heat" the damaged area only then apply the ME?

It seems as stated and as I already knew when the run reaches the cooler portion of the glass the run stops? So wouldn't it make sense to only heat the damaged void instead of the entire WS? It seems the run would hit a cooler section of the glass quicker by doing so leaving you with a much shorter run.

Just a thought! Please comment, I'm sure this could help alot of others here on the forum!

That has not been my experience, but then again I have not had more trouble with warm glass than cold glass like some others on the forum report. I prefer working with warm glass whenever possible and believe consistency, as in warming a large area or the entire windshield, works best.