Can the internal windshield laminate fail?

[kawscott]

On a 15 yr old lof windshield in a trans am with clean, clear, unscratched outter and inner glass if you look through the windshield in bright sun you can see evenly spaced verticle tracks like maybe the plastic was applied in liquid rows and then sandwitched between the glass layers during manufacture. Is this normal age related? Will these be visible in a new windshield?

[screenman]

Are you sure they are not the heating elements, very fine black lines. That is of course if it is a heated windshield.

[DryStar]

I don't believe that model year offered a heated windshield. Also not sure if LOF was the OEM, I think it was PPG.

Try posting your question on GlassBytes forum. I'm sure somebody will help out. HTH

[Brent Deines]

The laminate can begin to fail in that old of a windshield even if it is in otherwise good shape, but in most cases you will first notice it around the edges. It will look like air space or if moisture has entered it may appear white. I've seen lam problems in the center of the glass as well but I've never seen the evenly spaced vertical tracks and as far as I know the lam is always applied in one piece. Unfortunately the new glass quality is not always all that great these days in my opinion and most, of not all, manufacturers are making a lot of their glass overseas. I used to have certain brands that I recommended for certain vehicles, often the same brand as the original equipment, because the fit and finish was noticeably better, but I don't do many installations these days so I really don't know if one brand is better than another for your vehicle.

Some new windshields appear wavy when looked at from an angle, but looking straight through you should not see any vertical tracks. If you have someone install the glass for you tell the installer that you want to inspect the glass in front of a good light our out in the sunlight before it is installed. If they know you are going to demand quality they are more likely to demand quality from their supplier rather than just paying the lowest possible price for the glass and accepting an inferior product.

[DryStar]

Brent,

I would have to agree with you. I no longer install glass but previously operated a full glass service shop for over 10 years and had never seen vertically evenly spaced lines on any shield. I have had windshields with round shaped lightly visible splotches in lami but never what was describe here. It could be possible that somebody applied some type of windshield treatment and over lapped lines are appearing. That's only a guess though.

[kawscott]

Is there any kind of in the know technique for inspecting the clarity and optical accuracy of a new windshield before it is set in place?

[Brent Deines]

The supplier and/or glass shop should clean both sides of the glass and inspect with bright florescent lights behind it before ever installing in a customer's car. Defects of any kinds should be noted and pointed out to the customer or the windshield should be rejected. Doing so keeps customers happy and saves glass shops and suppliers time and money. I don't know of any advanced techniques but glass suppliers should all have a cleaning and inspection station.

[Glasseye]

kawscott
The problem you describe with the 15 year old windshield is a new one to me, a photo ( if possible ) might help, but the only the only things I can think of, other than de- lamination or vertical heating elements, is surface contamination, after market chemical application on the glass or dashboard glare ( with you mentioning bright sun).
Regarding inspecting the windshield for distortion prior to fitting. The most common method is to tilt the windshield to its approx. angle when fitted into the vehicle then look through the screen, from the inside out, at objects, such as vertical railings, at the same time moving your point of vision up and down and side to side. If distortion is present the railings will seem to bend optically. Distortion is caused by overheating of the glass during the shaping stage. Some glass distortion is allowed, but limited to the edge of the glass within approx. a couple of inches.

[screenman]

Just a thought, not possibly a toughened windscreen and what is being seen on sunny days is the spectrum colours that reflect back. These to the inexperienced could look watery.