Windsheild cracked overnight in the garage
#26
07-09-2010
Just thought I'd poke at teachers.
Remember the simple rule of thumb.
Those who can't do, teach. Those that can't teach, are in the phys-ed department. LMAO
#27
07-10-2010
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LOL Sorry to say, but you are wrong. Really old glass windows do get wavey and droop over many years. And I'm not talking about old houses of the 70 or 80's for all the young kiddies in here.
If you've ever been to an old church or farm house from the early 1900's with original glass, check it out.
If you've ever been to an old church or farm house from the early 1900's with original glass, check it out.
This is how old wives tales and other nonsense is passed on through the generations......what's next, are you going to "teach" me about "heat lightning"?
BTW moron, I taught MS science and still teach high school science.
Last edited by buckgnarly; 07-10-2010 at 06:28 AM.
#28
07-10-2010
OK, ONE LAST TIME.......SHOW ME THE EVIDENCE OF ANY SCIENTIFIC STUDY THAT PROVES THIS.....I WILL WAIT.....
This is how old wives tales and other nonsense is passed on through the generations......what's next, are you going to "teach" me about "heat lightning"?
BTW moron, I taught MS science and still teach high school science.
This is how old wives tales and other nonsense is passed on through the generations......what's next, are you going to "teach" me about "heat lightning"?
BTW moron, I taught MS science and still teach high school science.
The information about amorphous solids that I quoted was true, but after looking at more information, the flow effect of the non crystalline structures, was only evident at very high temperatures. Far outside what normal glass sitting in a window would be subject to.
Carl, I'd like to formally apologize for giving out misinformation. I should have read the information I had a lot closer.
You were in fact correct. I was wrong about antique windows flowing, but was correct about glass flow, just in the wrong context.
Glass flows under extreme temperatures, not under normal circumstances over time.
Antique glass in factory's and church's are thicker at different parts due to the technique of producing sheet glass using glass blowing techniques, not gravity's pull on glass.
I'm sorry for accusing you of not knowing what you were talking about, next time, before I shoot my big mouth off, I'll triple check my facts.
It's not easy for me to admit that I'm wrong
#29
07-10-2010
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The study I found this morning concluded that glass does in fact flow, but under higher than normal temperatures. The more research I did into antique glass, it was in fact due to poor manufacturing that the were not equally thick.
The information about amorphous solids that I quoted was true, but after looking at more information, the flow effect of the non crystalline structures, was only evident at very high temperatures. Far outside what normal glass sitting in a window would be subject to.
Carl, I'd like to formally apologize for giving out misinformation. I should have read the information I had a lot closer.
You were in fact correct. I was wrong about antique windows flowing, but was correct about glass flow, just in the wrong context.
Glass flows under extreme temperatures, not under normal circumstances over time.
Antique glass in factory's and church's are thicker at different parts due to the technique of producing sheet glass using glass blowing techniques, not gravity's pull on glass.
I'm sorry for accusing you of not knowing what you were talking about, next time, before I shoot my big mouth off, I'll triple check my facts.
It's not easy for me to admit that I'm wrong
The information about amorphous solids that I quoted was true, but after looking at more information, the flow effect of the non crystalline structures, was only evident at very high temperatures. Far outside what normal glass sitting in a window would be subject to.
Carl, I'd like to formally apologize for giving out misinformation. I should have read the information I had a lot closer.
You were in fact correct. I was wrong about antique windows flowing, but was correct about glass flow, just in the wrong context.
Glass flows under extreme temperatures, not under normal circumstances over time.
Antique glass in factory's and church's are thicker at different parts due to the technique of producing sheet glass using glass blowing techniques, not gravity's pull on glass.
I'm sorry for accusing you of not knowing what you were talking about, next time, before I shoot my big mouth off, I'll triple check my facts.
It's not easy for me to admit that I'm wrong
Well, thanks! It's all about learning and being able to pass along to others. There's many a time I have passed along bad info, but its' the ability to change and learn/accept new things (to include admiting when wrong) that helps further everyone's knowledge. The best people are the ones that do what you just did!
#30
07-12-2010
I am not sure I should continue the technical nature of this discussion, but since it has gone this far I would like to clarify some information.
I am a Chemist and use a "The Condensed Chemical Dictionary" to help me with a lot of my work. I am not saying anyone is right or wrong but here is the relevant portion of its definition. "Technically, glass is an amorphous, undercooled liquid of extremely high viscosity which has all the appearance of a solid. It has almost 100 % elastic recovery."
Since glass has extremely high viscosity,theoritically it could with enough pressure and time flow enough to permanently distort although that would be a very long time without the aid of heat. Glass does bend but not very far and will return to its original shape if it does not reach its breaking point.
I am a Chemist and use a "The Condensed Chemical Dictionary" to help me with a lot of my work. I am not saying anyone is right or wrong but here is the relevant portion of its definition. "Technically, glass is an amorphous, undercooled liquid of extremely high viscosity which has all the appearance of a solid. It has almost 100 % elastic recovery."
Since glass has extremely high viscosity,theoritically it could with enough pressure and time flow enough to permanently distort although that would be a very long time without the aid of heat. Glass does bend but not very far and will return to its original shape if it does not reach its breaking point.
Last edited by IN2 FX4; 07-12-2010 at 11:55 AM.
#31
07-12-2010
I am not sure I should continue the technical nature of this discussion, but since it has gone this far I would like to clarify some information.
I am a Chemist and use a "The Condensed Chemical Dictionary" to help me with a lot of my work. I am not saying anyone is right or wrong but here is the relevant portion of its definition. "Technically, glass is an amorphous, undercooled liquid of extremely high viscosity which has all the appearance of a solid. It has almost 100 % elastic recovery."
Since glass has extremely high viscosity,theoritically it could with enough pressure and time flow enough to permanently distort although that would be a very long time without the aid of heat. Glass does bend but not very far and will return to its original shape if it does not reach its breaking point.
I am a Chemist and use a "The Condensed Chemical Dictionary" to help me with a lot of my work. I am not saying anyone is right or wrong but here is the relevant portion of its definition. "Technically, glass is an amorphous, undercooled liquid of extremely high viscosity which has all the appearance of a solid. It has almost 100 % elastic recovery."
Since glass has extremely high viscosity,theoritically it could with enough pressure and time flow enough to permanently distort although that would be a very long time without the aid of heat. Glass does bend but not very far and will return to its original shape if it does not reach its breaking point.
#34
08-10-2010
Glass is an amorphous solid, which means that it hardens without crystallizing.
"Evidence against glass flow
If medieval glass has flowed perceptibly, then ancient Roman and Egyptian objects should have flowed proportionately more—but this is not observed.
If glass flows at a rate that allows changes to be seen with the naked eye after centuries, then changes in optical telescope mirrors should be observable (by interferometry) in a matter of days—but this also is not observed. Similarly, it should not be possible to see Newton's rings between decade-old fragments of window glass—but this can in fact be quite easily done.
Likewise, precision optical lenses and mirrors used in microscopes and telescopes should gradually deform and lose focus. This is also not observed."
If medieval glass has flowed perceptibly, then ancient Roman and Egyptian objects should have flowed proportionately more—but this is not observed.
If glass flows at a rate that allows changes to be seen with the naked eye after centuries, then changes in optical telescope mirrors should be observable (by interferometry) in a matter of days—but this also is not observed. Similarly, it should not be possible to see Newton's rings between decade-old fragments of window glass—but this can in fact be quite easily done.
Likewise, precision optical lenses and mirrors used in microscopes and telescopes should gradually deform and lose focus. This is also not observed."
#35
08-10-2010
One proposed idea of why they are thicker at the bottom is that due to teh rollers heating while the glass was rolled out, expansion occured creating a thinner part of glass. The rollers would definately thermally expand due to the temperature of the glass.
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