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Toughened Glass

Posted: Tue 17 Aug, 2010 10:11 am
by Dave
Hi

A customer has bought in a piece of antique beadwork in an old deep oak frame. She wants it converting into a tea tray, no problems with that, I can source some handles and have some felt for the bottom.

Am I right in thinking that ordinary float glass would not be safe for this purpose?

Would toughened glass be better, or is there something else more suitable?

Can toughened glass be cut in the same way as float, I have a wall mounted Fletchcer?

Can it be bought pre cut, the piece itself is approx 300 x 600?

Is it horribly expensive?

Thanks

Dave

Re: Toughened Glass

Posted: Tue 17 Aug, 2010 10:22 am
by Dermot
Ask your local glass supplier for a piece of laminated glass cut to size, the same type of glass that should be used in doors these days and that is used in car windows.

Re: Toughened Glass

Posted: Tue 17 Aug, 2010 11:10 am
by Jonny2morsos
Glass & Mirror will do it cut to size for you. You can order through Wessex Pictures in Dereham.

Remember it will have a kite mark etched in the surface.

Re: Toughened Glass

Posted: Tue 17 Aug, 2010 11:19 am
by Dermot
Jonny2morsos wrote:

Remember it will have a kite mark etched in the surface.

Only near the edge, you need to order it without the markings, the matkings are building regulations and are not needed for framing.

Re: Toughened Glass

Posted: Thu 19 Aug, 2010 12:56 pm
by realhotglass
Dave, just to clarify . . .

Toughened glass can't be cut.
It is cut to size as annealed float (or patterned) glass, then toughened by heating to ~ 560oC and air quenching.
Once this is done, the stresses placed in the glass sees it become a safety glass in that it shatters into tiny particles when it does break.
It is also very strong, usually 4mm toughened for example will take some serious hammer blows to cause breakage.

Back in my general glass days, I used to have a piece of 3mm clear toughened, oh around 14" x 5" or so, and to demo this, I'd whack the hell out of it against the wooden door frame of the glass shop I managed.
Worked great for numerous years until one day I was showing this to a vicar who wanted a thick toughened panel for a wall of a baptism font / bath (large everyone in the pool type).
Well, I did hit it just a bit too hard that morning, I think it was maybe the third hard blow to the door frame, and it went and blew to pieces, lol.
It was a good demo of how it is relatively harmless in little pieces, and he did end up buying the glass for the font, probably went for thicker glass than he originally thought he'd get.

As suggested, laminated glass (usually 2 bits of 3mm (1/8") float laminated together with 0.38mm PVB interlayer) will be equally as good.
Strong and safe, interlayer will hold glass together if broken.

You can order toughened or laminated glass without a safety motif, at least here in Oz.
Advise supplier there that it isn't for required human impact considerations and they should have no legal worries with supplying less the motif.

Re: Toughened Glass

Posted: Thu 19 Aug, 2010 2:56 pm
by Jonny2morsos
Jonny2morsos wrote:Glass & Mirror will do it cut to size for you. You can order through Wessex Pictures in Dereham.

Remember it will have a kite mark etched in the surface.

Now I come to think of it the last piece I was supplied did not have the kite marking. But if you do have it marked it does prove you have supplied what has been requested.

Re: Toughened Glass

Posted: Thu 19 Aug, 2010 3:59 pm
by CanvasChris
Just throwing a curved one at this....my thoughts.

tea tray... hot teapot.

not knowing about glass, would the toughened be ok?

Re: Toughened Glass

Posted: Thu 19 Aug, 2010 4:22 pm
by JFeig
thanks Realhotglass,

Now I understand what type of glass is the topic of discussion.

Us in N America call it "tempered glass"

Re: Toughened Glass

Posted: Thu 19 Aug, 2010 10:08 pm
by realhotglass
Yes Jer, toughened / tempered, same process.

Chris, toughened is actually the best glass to use in such circumstances, as it is very resistant to zonal changes in temperatures (think shower screen panel, hot water sprayed onto cold glass).
I have seen a lot of newer imported Chinese shower screen units increase over the past 5 - 10 years.
Some of these use dodgy toughened with perhaps particles if residual iron, that can explode under heat stresses.
Some also seen using laminated glass that, although more resistant to temps than old wired glass, can still crack under much less than that of toughened glass levels.

That said, teapot type temps should be perfectly fine for laminated glass of 6.38mm thickness.

Re: Toughened Glass

Posted: Tue 31 Aug, 2010 11:44 am
by Dave
Have been away on my hols, so a bit slow to say thanks for all the advice.

Dave