Bl***dy glass suppliers...

Errrmm, ...forget my earlier post.

My guess too - although I know little about toughened glass. Could it perhaps be ground? If it can't, why did she say on the phone they'd collect it and try? If they've almost certainly got to make a new one, why go to the bother of the extra journey?

Oh yes, I agree with that sentiment Its always good to keep a fair chunk back for this incentive. Brian

My wife and I have agreed that if we were ever in the position of doing a self-build, any architect mentioning custom glass would be immediately dismissed with extreme prejudice, probably involving a sawn-off shotgun.

Perhaps..... (I wouldn't!) They may get lucky - but, if you're putting anything of weight or value on it, I'd be a bit nervous. Glass is odd stuff - and can take a while to react to prior abuse... Hope it goes well. A

It's a unit Hi-Fi bits will sit on. Including a turntable - not something you want dropped. ;-)

The size is 1400 x 600 mm made from 10mm toughened glass.

I suppose they could just want to see the old one to make sure the mistake is theirs rather than mine. But the lass on the phone found my original drawing, and saw the problem immediately.

Shame you can't make some sort of identification mark on the piece you're sending back - just to see if they supply a brand new piece or attempt to 'bodge' the original...

I suppose they could 'un-toughen' the piece (you'd want to bring the glass up above the annealing temperature and then let it cool in a controlled manner before re-working it and re-toughening it) - but, given the cost of the glass and the c*ck-up potential, it's hardly worth it..

Perhaps they want it back just to make sure you're not one of those customers who's after a freebie?

or it was a local supplier who did not do the cutting/annealing in-house so wanted it back to return to whoever supplied them, with a request to get right second time.

No - I visited their workshop since they are local to give them the plans. And made a point of the different sized holes on the top 'shelf' to who I think was the foreman. And explained why.

Could see the very large workshop from the office when the door was opened. They basically do all the work there, except the toughening. And they explained they deliver and collect from the toughening place twice a week.

One thing did occur. Is there a way of telling it has been toughened? Talk about being suspicious. ;-)

You can untoughen it by annealing, then retoughen after modification

Easy - go near it with a drill or grindstone! Count how many pieces of glass you've got. If greater than 1, the glass _was_ toughened!

I don't think there's any requirement to mark toughened glass. The laminated stuff (car windscreens) has a little kitemark - but not on toughened.

A potential customer wanted an enormous cut-out (to accomodate the water pipes & waste) in the toughened glass shelf from their ?9.99 Lidl under-sink cabinet. I declined & sent them to my chum @ the local glass place. I think he declined as well...

On the old toughened car windscreens, you could see the stress pattern with polaroid specs. Like some sun specs. Wonder if this is the case with flat glass?

Possibly - not certain though.

In fused (art) glass we use crossed polars to spot glass that shouldn't have been fused together due to incompatibility... (hopefully at the testing stage!) but that's generally an indication of something that's going to go 'ping' at some time in the future.

While the toughened glass is under (deliberate) tension - it should be between the inside & outside layers - rather than across the plane of the glass as in my 'incompatible glass' example...

I've seen a mark indicating toughened on a pair of doors round the back

- probably installed 15+ years ago (pre me).

The few bits I've bought were marked and various people allege toughened glass *must* be permanently marked to show compliance with the appropriate standard.

See eg

If your glass has been toughened already then im afraid the only option ava ilable is disposal.I am an apprentice trained glass cutter (sadly a now dyi ng trade) and have 28 years experience so far in most aspects of the glass industry.Once glass has been processed and worked for toughening it becomes unworkable apart from maybe some minor polishing or grinding work.Logicall y thinking about it why would it be called toughened if it was still workab le,contrary to an earlier reply it is impossible to untoughen after being t oughened,

That's what I understood. Would it then be possible to enlarge 10mm holes to 20mm by some form of grinding? They said they were going to try, on the phone. Of course it may have been just talking bullshit as some trades do to the public. For whatever reason. ;-)

Thanks. It's not really my problem, except that if the holes could be enlarged, it might be quicker.

I'm surprised you say your trade is dying out given the popularity of glass everything these days.

My D/G sealed units (fitted by me) have a kitemark on the toughened ones.