I bought another old sedan. I have forgotten how to easily tell plate glass from safety laminated glass, assuming there are no visible stickers on the safety glass. I think safetly has a deeper thud, but there was some easier test someone posted here but I cant seem to find it. Plate glass just terrifies me!
Hold a lit candle or lighter up to the glass - if you see two reflections, it is safety (laminated) glass. One reflection, plate glass.
If you can see the edge, you can easily see the two pieces of glass with the lamination between. Also if it is older laminated glass you may see yellowing or bubbles around the edges. One other method is to place a coin against the glass and you will see a slight double reflection in the other piece.
Rap a coin edge (whilst holding it loosely) on the glass -- if the sound is dull, you have laminated glass. A sharp sound means plate glass. Try t on your modern car -- laminated windshield, plate side and rear.
I can see the 2 pieces of glass in my car with safety glass.
Hit with a hammer.
Hey, I like this Andy guy!...
So, how can you tell tempered--without a shattering experience?
Wife was mowing grass and mower threw a rock into my passenger side window of my Dodge Colt; SHATTERING EXPERIENCE. One thousand pieces!!! Got the replacement window today. Now have to install.
Well, that's one way to get out of being asked to mow the lawn anymore. . . . .
Notice how much more expensive side glass is compared to windshield glass?
So, how can you tell tempered--without a shattering experience?
One way is to carefully study every inch of the glass; tempered glass will have two slight little depressions around one edge normally where it was clamped for the heat treatment process.
David, It's doubtful that you will find tempered glass in an old car. You can have it made but it is expensive. After each piece is cut to size it must be sent to be tempered. The flat glass windows we have in our old cars is easily cut from laminated glass at a much lower price.
I realize that it is probably seldom used, but I have known a few who did use it. Yep, I'd rather deal with laminated myself!
There certainly are definite advantages to laminated glass, especially in an accident. But I tend to prefer tempered glass, especially if there is an exposed edge, because at a casual glance it does look more correct.
It is easy to tell laminated on an exposed edge, just by examining the edge. If no edge is exposed (like some windshield frames, or fixed rear windows), either the "quarter" or "candle" test can be used. All it takes is a sharp light (like a candle flame) or sharp reflection (quarter is a recommended item) at an angle to the glass so that you can see the reflection in the glass. The sharp light will show two distinct reflections in the laminated glass, but only one clearly in either plate glass or tempered glass. (There actually will be a second or third reflection in glass from the inner surface of the outer plane which SOME sharp-eyed people can spot, but most will not, so don't get too confused by my drift.)
Telling plate from tempered is more difficult. Often, the best way is what Brian B mentioned. Somewhere on the class should be probably two dimples or wrinkles where the glass was held for the tempering process.
Another way to tell safety glass from plate glass is to look for the "bug".
Many states require by law that all automotive glass be marked as such. Glass shops refer to the little etching as a "bug". It should identify it as automotive glass (although it may not say so as such) and also will usually tell whether it is tempered or laminated.
Sometimes you can find a glass shop that will leave the bug off if you ask them to. For some reason, they tend to be more willing to do so if you refer to it as a "bug". Another thing you can do if you want the glass without the modern touch, is request a "shelf" made to order. Most glass shops will consider leaving the bug off if the receipt states it is a curio shelf.
So, look at an edge if you can, bugs near a corner, or tempering dimples, and sometimes a candle or a quarter in bright light.
Drive carefully, and enjoy, W2
We used to inspect ALL T's on tour and I checked many a windshield. It is super easy if you have ever done it since there is a huge difference in sound between safety glass and plate glass. Best way is to use a ball point pen. Just tap the pen directly point first to the glass with a light tap. Plate glass will "ring" nice with a high pitched and loud "clink" sound while safety glass will give you a most definite DULL thud without any ringing sound at all. Once you have done one of each you will realize there is no way to get them confused.
AFAIK, the 'bug' is only required on the windshield glass. The side glass is not held to the same strength test as windshield, and can usually be inspected by looking at the edge.
Some 25 years ago I did a '31 A Fordor and was able to have the glass cut without bugs. I had a rubber stamp made that looked like the Ford XXX bug and etched each window myself. While it wasn't 100% exactly like the original, it was close enough that I never lost points on them, and actually gained a few! I think the difference was that the original Ford bug also included the date in code. Been too long, I forget the finer details!
I think Andy has the best method.
It's great first hand experience to see exactly what happens when plate glass breaks........it's pretty scary!
Scary, yes. I was changing the window motor regulatory on driver side of a Mercury Marquis one Saturday night, about 9:30 PM. Had to pull the window, which was riveted into the rail. So just about finished the project and used bolts/nuts to replace the rivets. Tightening with a racthet and just gave it one more little snuggy! Shattered into a million pieces. Came into the house and wife asked if I fixed it. Yeah, I told her I really FIXED it!!!
Also changed the Dodge colt window last night. Mitubishi used screws through the metal rail (not the glass) to mount the window glass. Piece of cake!!
The glass shops in my area never have an issue producing the glass without bugs. I let them know that I'll be marking it myself with period correct markings.
fordscript.com produces all the marks from 1928 on. They sell dated stencils and the acid to apply the marks.
That's neat! Wasn't available when I did the '31, and sounds like a much more reliable way to do it--I did a LOT of practicing with the rubber stamp to get to where I could do a pretty good bug, but they still weren't perfect--but boy did they get a lot of comments, "Where'd he find this glass???" was the usual.