http://www.alumaxbath.com/tech/tgb.htm

On 29/01/2010 10:30 AM, Rod Speed wrote:
Jonno wrote


It can happen that the glass is only esposed to the suns heat leading to the metal restricting it and it cracking,,
shattering etc.

Thats not even possible with a frame.


If both are exposed at the same rate that would be true..Like air temperature by itself.

Its even more true of the sun where you cant stop the metal
frame being exposed to the sun with a glass topped table.

Its MUCH more likely to actually be a problem with the glass itself,
and we do see the same problem with stuff like oven doors etc,
the cheap shit from china having a real tendency to explode.

Thats actually due to the glass they are made from, not the mounting.



On 29/01/2010 8:55 AM, Rod Speed wrote:

Jonno wrote



If the glass is constricted by a metal frame, the expansion of the
glass, and slower rate of expansion of metal

In fact metal has a higher coefficient of expansion than glass.
http://en.wikipedia.org/wiki/Coeffic...ious_materials



could cause pressure to build up in the frame, with the resultant
breakage,

That wasnt in fact seen with the old style steel framed
windows that you dont see much of anymore.



Thats why a properly designed table will have rubber expansion
sealing material on the outside of the frame...

Dunno, are they in fact mostly framed at all ?



Rod Speed wrote


0tterbot wrote


wrote



This one got full sun each



day, to charge the glowing frog/etc garden lights {:-), so there
would have been some expansion movement.


glass doesn't like the sun!!! this is probably the origin of the
problem.


Unlikely, I have 13 8'x8' patio doors, 7 of them on the north side
of the house. I dont have any conventional windows except in the
bathrooms, the bedrooms have one or two patio doors. The ones on
the north side get sun every sunny day and not one of them has
ever broken.


dh is a brewer so naturally we scab crown-top bottles from
anywhere& anyone. however, you can't always tell if they've been
left in the sun too long,& very occasionally, they just explode
on a hot day or after some minor contact with something. which is
unfortunate if they happen to be full of beer at the time.



if we know a bottle has been in the sun, best just not to use it.
(same with tables, i suppose).



Nope, fraid not, most obviously with windows.




--

Jonno wrote:

Not even possible with the frame partly exposed?

Nope, because the top is glass so the sun will shine thru that, even if its translucent etc.

Its also possible if the sun shines thru the glass first.

Nope.

Theres many variations
I even heard of glass cracking due to a flag pole putting a shadow on the window, causing uneven heating.

Dont believe it. You dont get that effect with windows and patio doors.

The temperature was on the lower side in Canada.

You dont get that effect with windows and patio doors even in Canada.

As far as poor quality glass goes, that's possible, but unlikely with modern methods of making glass.

Have fun explaining the rash of that with oven doors and alleged pyrex food things which arent.

Damaged glass is usually the problem when the article is made.

Not with china. Its trivial to prove that the problem was the
glass itself, its trivial to work out what sort of glass it was.

Then the other things like bad handling, temperature cause the glass to shatter....

How odd that you dont get it with windows and patio doors.


On 29/01/2010 10:30 AM, Rod Speed wrote:
Jonno wrote


It can happen that the glass is only esposed to the suns heat
leading to the metal restricting it and it cracking,, shattering
etc.
Thats not even possible with a frame.


If both are exposed at the same rate that would be true..Like air
temperature by itself.
Its even more true of the sun where you cant stop the metal
frame being exposed to the sun with a glass topped table.

Its MUCH more likely to actually be a problem with the glass itself,
and we do see the same problem with stuff like oven doors etc,
the cheap shit from china having a real tendency to explode.

Thats actually due to the glass they are made from, not the mounting.



Bakers warn that you should place a towel over the oven window when
pulling anything with moisture out of a hot oven.
A little bit of moisture on very hot glass can cause the window to
shatter.
On 29/01/2010 8:55 AM, Rod Speed wrote:

Jonno wrote



If the glass is constricted by a metal frame, the expansion of the
glass, and slower rate of expansion of metal

In fact metal has a higher coefficient of expansion than glass.
http://en.wikipedia.org/wiki/Coeffic...ious_materials



could cause pressure to build up in the frame, with the resultant
breakage,

That wasnt in fact seen with the old style steel framed
windows that you dont see much of anymore.



Thats why a properly designed table will have rubber expansion
sealing material on the outside of the frame...

Dunno, are they in fact mostly framed at all ?



Rod Speed wrote


0tterbot wrote


wrote



This one got full sun each



day, to charge the glowing frog/etc garden lights {:-), so
there would have been some expansion movement.


glass doesn't like the sun!!! this is probably the origin of the
problem.


Unlikely, I have 13 8'x8' patio doors, 7 of them on the north
side of the house. I dont have any conventional windows except
in the bathrooms, the bedrooms have one or two patio doors. The
ones on the north side get sun every sunny day and not one of
them has ever broken.


dh is a brewer so naturally we scab crown-top bottles from
anywhere& anyone. however, you can't always tell if they've
been left in the sun too long,& very occasionally, they just
explode on a hot day or after some minor contact with
something. which is unfortunate if they happen to be full of
beer at the time.

if we know a bottle has been in the sun, best just not to use
it. (same with tables, i suppose).



Nope, fraid not, most obviously with windows.

Jonno wrote:

http://www.alumaxbath.com/tech/tgb.htm

Nice theory, pity you dont get any sunlight effect with
patio doors which by law have to be tempered glass.

On 29/01/2010 10:30 AM, Rod Speed wrote:
Jonno wrote


It can happen that the glass is only esposed to the suns heat
leading to the metal restricting it and it cracking,, shattering
etc.
Thats not even possible with a frame.


If both are exposed at the same rate that would be true..Like air
temperature by itself.
Its even more true of the sun where you cant stop the metal
frame being exposed to the sun with a glass topped table.

Its MUCH more likely to actually be a problem with the glass itself,
and we do see the same problem with stuff like oven doors etc,
the cheap shit from china having a real tendency to explode.

Thats actually due to the glass they are made from, not the mounting.



On 29/01/2010 8:55 AM, Rod Speed wrote:

Jonno wrote



If the glass is constricted by a metal frame, the expansion of the
glass, and slower rate of expansion of metal

In fact metal has a higher coefficient of expansion than glass.
http://en.wikipedia.org/wiki/Coeffic...ious_materials



could cause pressure to build up in the frame, with the resultant
breakage,

That wasnt in fact seen with the old style steel framed
windows that you dont see much of anymore.



Thats why a properly designed table will have rubber expansion
sealing material on the outside of the frame...

Dunno, are they in fact mostly framed at all ?



Rod Speed wrote


0tterbot wrote


wrote



This one got full sun each



day, to charge the glowing frog/etc garden lights {:-), so
there would have been some expansion movement.


glass doesn't like the sun!!! this is probably the origin of the
problem.


Unlikely, I have 13 8'x8' patio doors, 7 of them on the north
side of the house. I dont have any conventional windows except
in the bathrooms, the bedrooms have one or two patio doors. The
ones on the north side get sun every sunny day and not one of
them has ever broken.


dh is a brewer so naturally we scab crown-top bottles from
anywhere& anyone. however, you can't always tell if they've
been left in the sun too long,& very occasionally, they just
explode on a hot day or after some minor contact with
something. which is unfortunate if they happen to be full of
beer at the time.

if we know a bottle has been in the sun, best just not to use
it. (same with tables, i suppose).



Nope, fraid not, most obviously with windows.