Opened the Garage door to utter carnage!

[LowStandards]

So there i was last night being moaned at by the missus, 'cause her dustpan or summat was in me Garage. So i trundles out in the cold and dark, opened her up and... BOSH

Thought someone had broke in at first, but then realised the front screen from the Imp which has been sitting in the roof space of my Garage untouched for nearly 2 years had just given up!

Any ideas why it would suddenly do this?

[akku]

its been lying in a "stressed" position. Curved / toughened glass should be stored upright so its not under tension. Or so I have always been told.

[LowStandards]

I see, its taken 2 years bless it! Good I don't really need it ;p

Took me ages to clear up mind!

[akku]

reminds me I have a Plymouth windscreen stored flat which I put on the roof of my Capri as a temporary move a few weeks back. I aught to go prop it up properly....

[Ratdat]

Toughened glass is wierd. I've had screens stored flat with no problems at all yet i've had one which was stored upright on thich cardboard shatter for no apparent reason as I picked it up. Whenever I have to transport glass it usually goes flat but I bundle a load of rags under it to support it in the center. never had one bust yet. If you're storing long term though, upright is the only way.

[Deleted]

Oooo interesting. I might lift the one up in the Anglia, it's sat on the back seat with a load of stuff piled on top of it

[Mr S]

I still say it was an earth tremor....

[BenzBoy]

Interesting, I never knew that could happen. So, if a screen has been stored flat, can it be weakened by storing it in such a way?
What I mean is, if someone was to fit a screen after storing it in a stressed position for a while, could it shatter after fitting it? Scary!

[peachey]

I don't think it weakens it, just likely to break, but if it doesn't break I think its safe once you take it out of the position.
I remember leaving a rear windscreen on a stand I had just taken out to repair the rust(sitting opposite to how yours was if it makes a difference). I left a screw driver and tinsnips on it, with in no time it shattered. Asked the bloke who does the windscreens, mate who used to work where I do, and find that its no unusual, looking at it I think you should count yourself very lucky it it didn't go sooner, cause it appears you had a sled or something on it.

[antdat]

hmm better check how i have stored the glass for the datsun, sure it's upright :S

[LowStandards]

Its a 70's luggage rack that weighs next to fook all. I just find it odd it did it after 2 years when it literally hasn't been touched!

As for an 'Earth Tremor' - I'll give you a bloody tremor next time i see ya

[trg1984]

tis a bit weird but i don't think storing stuff on glass is a good idea really.

[akku]

its not that it weakens it but that as the glass is curved, laying it out flat means that weight os being applied to only part of the screen and not in the way it was designed to take it. So a stress builds up, and remember that glass is not a solid, its a liquid which tends to be solid at normal temperatures. Look at how the windows in old houses have sags in them....

[pictonroad]

alistairk said:

its not that it weakens it but that as the glass is curved, laying it out flat means that weight os being applied to only part of the screen and not in the way it was designed to take it. So a stress builds up, and remember that glass is not a solid, its a liquid which tends to be solid at normal temperatures. Look at how the windows in old houses have sags in them....

Common fallacy, glass is a solid, this all started from a mis-translation in some scientific literature (My notes are at home ) and the old house theory compounded it. The old glass makers couldn't get completely flat glass, when the builder of olde worlde went to putty it in, he put the fat edge at the bottom as it was more stable.

I was sitting on the lawn once and the glass in my mum's Maestro exploded, I got the blame

[Lankytim]

Ive heard that its a semi-liquid too. Glass in churches that are 100's of years old are thicker at the bottom than at the top because of this. Just what ive been told though, could have been fed a load of twaddle.

[akku]

really, I've heard people who know more abut stuff than me saying so as well.

Exploding screens in cars is often due to them bening bonded in without any scope for expansion or contraction of the matal of the car being at a different rate to that of the glass. In places like Texas it used to be common for people to deliberately crack their windscreens and rear screens when bonded glass first came out because that way the screen could give and take enough to deal with themetal expansion and contraction in the blazing hot summer days and cold nights... Vauxhall Victors used to be famous for it as they were the first of the British cars to have bonded screens (well, mass produced anyway) and they used to break their screens regular until they got the hang of using a flexible bonding agent.

[pictonroad]

Like an old VW, it's not as simple as all that and there's more than one answer...

The old churches having thicker glass at the bottom is definitely not because the glass has run as it wont do this. However, there are about 19 states of matter and several between the old school 'solid' and 'liquid'...

I think that current thinking has glass somewhere south of an actual solid on the molecular level but it certainly doesn't run like we might expect a liquid to.

Have a look here...math.ucr.edu/home/baez/physics/General/Glass/glass.html

James

[Anglia68]

I had a windscreen stored on top of my wardrobe until the early hours of one morning when it shattered with a hell of a bang,instantly waking me up,as lumps of glass rained down on me in the dark.Damn near had to change the bedsheets after that.

[Mr S]

2002gimp said:

As for an 'Earth Tremor' - I'll give you a bloody tremor next time I see ya

Is that a promise?!!