Windshield Repair Forum

Sometimes I find myself working on a fleet truck later in the day when the sun is shining though the back cab window right onto the backside of the windshield. I hope this doesn't sound like a dumb question....but I was wondering if I should be using a UV shield on the back glass or the inside of shield to prevent any possible UV exposure?

Auto Glass filters out most of the UV thats why you can drive for hrs without getting sunburned. If I understand the science its something in the laminate layer. But the answer is probably just in case since some does go through.

Glasstarz first instincts were right... don't worry at all about UV coming through form the inside of the w/s. The w/s blocks the UV.

Also, even if it didn't block all of it, that time of day the sun's UV is very weak anyway.

As a test, try putting a drop of resin on the inside of the w/s in full sun and see if it cures.

I have done that and I got tired of waiting...

GlassStarz, your absolutely right UV will not penetrate TINTED laminated glass. I actually did a test years ago took two pieces of tinted laminated glass put resin in between the two sat it out in the direct sun it never did cure after an hour or so.

CLEAR Laminated would be a different story I would think I would have to try that one to see? To be perfectly honest I haven

StarQuest.

I ALWAYS UV shield the inside and outside when there is any chance of light coming through a backlite or sidelite of a vehicle. (I take it you are refering to tempered glass in those cases.)

Perhaps I am overly cautious but I even UV shield when working in the customer's garage. I am well aware of the bounce properties of UV rays and it is better to be safe than sorry.

Seems like everybody has a little different view on this subject. I keep thinking there has to be some UV penetration through glass though. If not how do you explain all the purple tints, faded dashes and car interiors?

Actually the trucks I'm speaking of are freight haulers with clear tempered back glass. What I was concerned about is possible premature curing or thickening of the resin, especially when working those tight multiple legged monsters that require some additional time.

I agree, the best way to find out is set up a test like suggested or simply just play it safe like Desertstars.

Thanks for your input

There may be some amount of UV through some glass. You could check it this way nest time you are working on one like that... put a drop of pit resin/tab on the outside where you are working and cover it with black tape, etc to completely block all outside exposure. The only way it will cure is if the UV is coming through the w/s.

I might stick a shade of some sort inside the cab just to block the annoying glare of the sun... regardless of the UV issues..

Precisely, StarQuest.

Why take the time to test when a simple application of a UV backshield when in doubt precludes any potential problems?

Cover, cover, cover when there is any doubt whatsoever.

How much time does THAT take?

Glassdoctor,

I really appreciate and understand what your trying to tell me. Forgive me for saying this....but I'm not concerned about the cap curing, I'm more concerned with penetration and filling the tips of legs. If for some reason the UV leakage is preventing me from accomplishing that I need to adust my method or shielding. I think the only way I can figure this out is by placing a vial full of resin inside the vehicle and see if viscosity changes within the 5-10 minutes it takes to repair. My biggest problem with WSR is being satisfied with my results and knowing I tried everything available to get me there!

Thanks for your help and sharing your experience!