Windshield Repair Forum

But reappears under pressure or at neutral. Had a star break the other day that had about 10 half inch long legs extending out. After repeated vacuum and pressure cycles it became obvious that the legs only cleared up and disappeared when under vacuum. Those legs had obviously filled in with resin and no heat was used during the repair on a windshield that was about 70 degrees. I cured this repair under vacuum and it looked great. I've nevver had one act that way before. Any idea why?

Without knowing more specifics, couple thoughts for you to consider...

Natural light refraction
Refractive index of resin
Overpressure
Moisture
etc...etc...

I have found that some repairs although full appear more visible pre cure and after they are cured look totally different. Usually stars and batwings. Sorry I can not wrap myself around the curing under vacuum technique. Goes agains the objective of our service as vacumm not only removes air, it removes some resin as well which would not ensure a structurally sound repair. For myself the first priority is a structurally sound repair with appearance second.

Curing under vacuum is not a tecnique of mine. That is the first time I have done that. No moisture in break. Did not use too much pressure. Not an issue of resin or refractive index. Must be the etc, etc, etc, you are talking about. It was a perfect looking repair on my neighbors car. I was puzzled by it. Even did some flexing on the completed repair to see if there was any evidence of legs opening or instability. Nothing. Appears to be a repair both structurally sound and it nearly vanished. Go figure. Guess it was just one of those odd flukes.

I think you might find that the refraction index of uncured resin is slightly different from cured resin. As for looking better when on vacuum, I have seen the same thing on many occasions, but have no idea why.

Dont know if this is the case here but often you lose pressure on a star or crack because it seaps out the legs often you will see a little resin on the leg surface pace a cure tab on it this should seal it up then repair as usual. Time and cycles are the secret to stars
The thing looks better sometimes with vac because it pulls all the air etc out looking better doesnt mean better repair heat often will open a leg and let the resin in

For the record, I have done over 10,000 repairs and have never seen one react the way this one did. I'm not a greenhorn at this trade. I worked and worked through time and cycles on this star and ONLY under pressure would the legs dissapear.
It wasn't just a slight difference in visual appearance, it was a substantial difference. I went back over to my neighbors home just about an hour ago and examined the damage again and it's nearly impossible to find. I even spoke to him about why this is puzzling to me and explained that if it shows any sign of reappearing to let me know.

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