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View Full Version : O.T. Glueing Glass



garyphansen
10-06-2008, 07:28 PM
Someone wants me to build him a coffee table (shadow box) with a glass top. I have a couple of pieces of tempered glass that are 1/8" thick. I would like to "glue" them together so I would have a 1/4" thick piece of tempered glass. Anyone here ever do this? Anyone have any ideas on how to go about this? Gary P. Hansen

Evan
10-06-2008, 08:59 PM
I don't recommend trying that with tempered glass. The strain pattern in each piece will not be the same. If they are glued together it is likely that the difference in linear expansion with temperature will cause both pieces to shatter if subjected to a sudden temperature change such as an iced drink being set on the table. Tempered glass often has surface strain that approaches the ultimate tensile limit of the material. In some cases it does exceed it and the glass will shatter spontaneously. By laminating two pieces the under piece will be insulated from the top piece but will still undergo additional stress from changes in the top piece dimensions.

mechanicalmagic
10-06-2008, 09:40 PM
I believe automotive windshields are made that way. Tempered glass laminations with a plastic layer in between.
http://en.wikipedia.org/wiki/Laminated_glass

My issue would be gluing without bubbles.
I have no idea how to do that.

Dave J.

smiller6912
10-06-2008, 09:47 PM
The key here is "tempered". Auto glass... "laminated glass is produced by bonding two or more layers of ordinary annealed glass together with a plastic interlayer"

mechanicalmagic
10-06-2008, 11:29 PM
The key here is "tempered". Auto glass... "laminated glass is produced by bonding two or more layers of ordinary annealed glass together with a plastic interlayer"

I have replaced several auto windows. NONE were annealed, they broke into many small fragments. Which is the indication of of a tempered or toughened glass.

It is true that laminated glass can be made from annealed or tempered glass.

Dave J.

Evan
10-06-2008, 11:35 PM
Yep, windshields are not tempered glass but are laminated annealed safety glass. They shatter easily but the laminations keep the glass from forming a lot of loose sharp pieces. It also helps to prevent the occupants from being ejected.

The side windows are usually tempered glass which when broken disintegrates into glass gravel. Tempered glass has been heated and then quenched with cold air to produce strong surface strains that help to prevent the surface from being penetrated. It forms distinct patterns of strain that can easily be seen in car windows when viewed through polarized sunglasses during daylight on a sunny day. The scattered light reflected from the blue sky is highly polarized and so together with the polarized glasses will reveal the strain patterns produced by the stresses in the glass. Those patterns are not seen in a windshield since it isn't tempered.


It is true that laminated glass can be made from annealed or tempered glass.



While tempered glass might be laminated I have never heard of it.