Toughened glass

[michael adams]

Looking to replace a broken pane of glass and checking prices on Google I noticed plenty of suppliers quoting for 4mm clear float and 4mm clear toughened. And giving instructions on how to price a particular cut size.

However when checking out toughened glass on Google there it's claimed (as I'd always thought to be the case) that " Any cutting or grinding must be done prior to tempering. Cutting, grinding, sharp impacts and sometimes even scratches after tempering will cause the glass to fracture."

So are there various kinds of "toughened" (as opposed to laminated which is thicker) 4mm glass ?

michael adams

...

[Adrian Brentnall]

As far as I know - the process is

- cut to size

- toughen

as the toughening process induces deliberate stress in the glass (by heating / cooling), and, once toughened, you can't work the glass...

Adrian

[Lobster]

On 03 May 2014, Adrian Brentnall grunted:

But I don't see anything on the original link which suggests the process is anything other than that. Is it just that they price up toughened glass per square metre?

[Nightjar]

No. It just means you need to tell them the size you want, they will supply it to that size and that the price will be based upon that pricing structure.

Colin Bignell

[michael adams]

Indeed. Presumably with toughened glass then, they need to order it from the manufacturer who would then cut it to size and treat it.

Given the price differential of 10 per sq. mtr and with a minimum charge of 12.15 per pane I'm just surprised it would be worth anyone's while given the costs of extra treatment and transport from the manufacturer.

michael adams

...

[John Williamson]

Some of the larger firms have the heat treatment plant on site, so they buy in normal float glass, cut it to size, grind the edges smooth and feed it into the oven.

[harryagain]

You have to have toughened glass by law if it's below a certain level. Eg, lower panels in doors.

Toughened glass is marked as such if you look. A safety thing for if it breaks, there are no big shards to cut youself on.

[Lobster]

On 03 May 2014, "Phil L" grunted:

Heh. I once bought a sheet of toughened about 48" tall by 18" wide, for a door panel. I got it home no problem, prepared the frame, then picked up the pane and was holding it at its top corners between my thumbs and forefingers, lining it up with the frame. Suddenly the bloody thing just spontaneously exploded. I hadn't knocked it or even touched it against anything whatsoever, but ended up with a pile of tiny fragments of glass at my feet and a surprised expression on my face.

To the supplier's credit, he did replace it FOC, despite claiming that he'd never heard of that happening in his life!

[fred]

In article , Lobster writes

Was this before or after the start of the touch-turns-to-skittles adverts :-)

[Nightjar]

On 03/05/2014 19:12, harryagain wrote: ...

Wrong again Harry. You have to have safety glazing or fit adequate safety guards. Safety glazing can be toughened glass, laminated glass, various plastics or even ordinary annealed glass, provided it is thick enough not to be at risk of breaking. That varies from 6mm glass, which must be no more than 250mm wide and no more than 0.5 sq m in area to

15mm or thicker, which can be used for any size of glazing in critical locations.

Colin Bignell

[Lobster]

On 03 May 2014, fred grunted:

Before! But I can tell you - that's exactly what it was like!!

[Andy Burns]

That would make for an interesting looking door to be Part L compliant, I'd have thought ...

[GMM]

Where I go (local glas merchant), they cut it, then take it somewhere to have it toughened, so it takes a day or 2 from ordering.

[michael adams]

What I meant was why it would be worth anyone's while offering it at that price. i.e a piece of glass cut in the factory and marked with the customer number, dunked in this chenmical bath and or furnace and then delivered to a glass shop maybe miles way and all for 12.50 retail.

michael adams

...

[fred]

In article , michael adams writes

Probably better to think of it on trade quantities and margins.

Say works on 100% margin so he buys at 6.75 and sells at

12.50. He quotes a 5 day turn on toughened but part of that is actually to get a decent batch job to the factory, say 100pcs. So, in a week, he takes orders, emails to the supplier at the end of the week and takes 675.00 in margin for next to zero work with delivery on Monday. Note that most glaziers or even moderate sized glass handlers do not make DG units themselves, it's more cost effective to have a factory that has a line running flat out producing them that it is to set up a small run in the workshop.

Note that this is not intended to imply sharp practice in any way, it is a normal retail vs wholesaler price relationship.

[Nightjar]

I like that thought. Two x 15mm sheets of glass with a 14mm gap and you have a double glazed 44mm thick external door.

Colin Bignell