Things I should have known before now... (1 Viewer)

[GO]

 

[7 - No tomorrow]

Ha!

Who needs johnnystress?

 

[Psycho Punk]

Now we need a song:

Oh, Oh, Pineapple head!

Remember Cabbage Head?

 

[billygannon]

"He's got a pineapple on his head, he's got a pineapple on his head..."

Pineapples also grow on the heads of mid-90's footballers

 

[washingcattle]

You can nulify you gag reflex while brushing your teeth by tilting your head all the way back. My molars are glad I heard this.

 

[pete]

You can nulify you gag reflex while brushing your teeth by tilting your head all the way back. My molars are glad I heard this.

or try squeezing your thumb in your fist

 

[washingcattle]

If you brush for as long as I do your thumb would be blue by the time you finish.

 

[ann post]

when cutting a glass bottle using a glass cutter, after you have scored the bottle the whole way round a number of times, be sure to tap it apart immediately. why? because the glass grows back if you dont. WHAT?? the glass heals. WHATT??? THE FUCKING GLASS HEALS.

i dont think anything has ever been the same since i found out that glass can heal/grow back. everyone needs to know this.

 

[rettucs]

when cutting a glass bottle using a glass cutter, after you have scored the bottle the whole way round a number of times, be sure to tap it apart immediately. why? because the glass grows back if you dont. WHAT?? the glass heals. WHATT??? THE FUCKING GLASS HEALS.

i dont think anything has ever been the same since i found out that glass can heal/grow back. everyone needs to know this.

no it bleedin doesn't

 

[ernesto]

when cutting a glass bottle using a glass cutter, after you have scored the bottle the whole way round a number of times, be sure to tap it apart immediately. why? because the glass grows back if you dont. WHAT?? the glass heals. WHATT??? THE FUCKING GLASS HEALS.

i dont think anything has ever been the same since i found out that glass can heal/grow back. everyone needs to know this.

WHAT?!

 

[snakybus]

glass flows downwards, like an really, really viscous liquid

windows that are there for 100 years+ have more glass at the bottom than the top

so this is not unbelievable

 

[ann post]

you are making it worse mike.

 

[7 - No tomorrow]

glass flows downwards, like an really, really viscous liquid

windows that are there for 100 years+ have more glass at the bottom than the top

so this is not unbelievable

I don't think that's true either.

 

[Psycho Punk]

when cutting a glass bottle using a glass cutter, after you have scored the bottle the whole way round a number of times, be sure to tap it apart immediately. why? because the glass grows back if you dont. WHAT?? the glass heals. WHATT??? THE FUCKING GLASS HEALS.

i dont think anything has ever been the same since i found out that glass can heal/grow back. everyone needs to know this.

Nah, its grass grows back.

 

[snakybus]

I don't think that's true either.

It seems...you're right!It's a myth.

Analysis Shatters Cathedral Glass Myth
By C. Wu

A new study debunks the persistent belief that stained glass windows in medieval cathedrals are thicker at the bottom because the glass flows slowly downward like a very viscous liquid.

Edgar Dutra Zanotto [1] of the Federal University of Sao Carlos in Brazil calculated the time needed for viscous flow to change the thickness of different types of glass by a noticeable amount. Cathedral glass would require a period "well beyond the age of the universe," he says.

Suffice it to say that the glass could not have thickened since the 12th century. Zanotto reports his finding in the American Journal of Physics -- May 1998 -- Volume 66, Issue 5, pp. 392-395.
The study demonstrates dramatically what many scientists had reasoned earlier. "You would have to bring normal glass to 350 deg. Celsius (662 deg. F.) in order to begin to see changes," says William C. LaCourse, assistant director of the NSF Industry-University Center for Glass Research at Alfred (N.Y.) University.

Viscosity depends on the chemical composition of the glass. Even germanium oxide glass, which flows more easily than other types, would take 10^32 years (100,000,000,000,000,000,000,000,000,000,000) to sag. Zanotto calculates. Medieval stained glass contains impurities that could lower the viscosity and speed the flow, but even a significant reduction wouldn't alter the conclusion, he remarks, since the age of the universe is only 10^10 (100,000,000,00).

The difference in thickness sometimes observed in antique windows probably results from glass manufacturing methods, says LaCourse. Until the 19th century, the only way to make window glass was to blow molten glass into a large globe then flatten it into a disk. Whirling the disk introduced ripples and thickened the edges.[2] For structural stability, it would make sense to install those thick portions in the bottom of the pane, he says.

Later glass was drawn into sheets by pulling it from the melt on a rod, a method that made windows more uniform. Today, most window glass is made by floating liquid glass on molten tin. This process, developed in the 50's by Sir Alastair Pilkington, and named for him makes the surface extremely flat.

The origins of the stained glass myth are unclear, but the confusion probably arose from a misunderstanding of the amorphous atomic structure of glass, in which atoms do not assume a fixed crystal structure. "The structure of the liquid and the structure of the [solid] glass are very similar," says LaCourse, "but thermodynamically they are not the same."

Glass does not have a precise structural setting point or conversely a melting point; rather, it has what's known as a glass transition temperature (a temperature when it begins to undergo a viscosity change), typically a few hundred degrees Celsius. Cooled below this temperature, glass retains its amorphous structure yet takes on the physical properties of a solid rather than a supercooled liquid.

"At first, I thought that the [sagging window idea] was a Brazilian myth," Zanotto wrote, but he soon learned that people all over the world share the belief. Repeated in reference books, in science classes, and recently over the Internet, the idea has been repeatedly pulled out to explain ripply windows in old houses. "For the lay person, it makes a lot of sense," says LaCourse.

In 1989, Robert C. Plumb of Worcester (Mass.) Polytechnic Institute suggested in the Journal of Chemical Education that definitive proof might require an instruction book written in the Middle Ages advising glaziers to install glass panes with the thick end at the bottom. Now if only such a handbook could be found.
From Science News, Vol. 153, No. 22, May 30, 1998, p. 341. Copyright © 1998 by Science Service.

---------------------------------------------------------------------
​

[1] Edgar Dutra Zanotto is a Brazilian materials engineer from the Universidade Federal de São Carlos (Federal University of Sao Carlos) (UFSCar) in Brazil. He currently teaches glass related subjects in that University for both graduation and post-graduation as he is the head of LaMaV, the Vitreous Materials Laboratory. In May 1998, Zanotto wrote an article in the American Journal of Physics relating to the false notion that observations of thick glass in old windows translated to the fact that glass is a liquid. Zanotto sought to calculate the flow of glass and found that at 414 Celsius (777 °F) the glass would move a visible amount in 800 years, yet at room temperature he found that it would take glass 10,000 trillion times the age of the earth.

[2] Editors note: Mr. Wu has it backwards, when you spin a disc of glass into what is known as a rondel the disc is thinner at the edge, not thicker, and thickens as you move toward the center.
​

http://www.glassnotes.com/WindowPanes.html

 

[7 - No tomorrow]

It seems...you're right!It's a myth.



http://www.glassnotes.com/WindowPanes.html

I take no joy in it.

 

[rettucs]

Alan Shatter wouldn't approve of this.

 

[rettucs]

or this dude, the most famous glazier of them all

 

[7 - No tomorrow]

 

[billygannon]

When Ely Cathedral was built they couldn't afford clear glass. Instead they hired painters to paint pictures of windows with images of the surrounding grounds. In one of these windows the face of Saint Dildus was painted over the face of a lamb.