glass thickness ?

wynpotter · Post by **wynpotter** » Thu Jul 03, 2003 10:08 am

I am new to fusing and am learning much as each firing comes out. From what I have read on this board and other info, glass is going to go to 1/4 in thickness if fired to full fuse and over. my question is what temp over full fuse or what flux can be applied to the glass to allow it to flow back to a thinner form.
Will this break down the glass and cause it to shatter on cooling.
I am getting very interesting pieces with 3 layers of wasser and a dichroic chip fired to 1400, but its too thick for earings. I am hoping to get the glass to flow thinner.

Thanks all for this forum, this is one of the best tech forums around on any subject wyndham@ac.net

Brad Walker · Post by **Brad Walker** » Thu Jul 03, 2003 10:30 am

By tack fusing and keeping the temperature below 1400, you're already keeping the glass from getting heated enough to flow to 1/4 inch thickness. If you heat it higher, then it will try its best to reach an equilibrium thickness of around 1/4 inch. (This is a law of physics, like gravity. Just as you can't reverse gravity, there is no "flux" that you can add to get the glass to "flow thinner".)

I can only think of two ways to trick the process and get a piece to be thinner and then remain at that thickness as it cools. The first is to to manipulate it when hot by rolling or a similar method (for instance, sheets are rolled when hot, then quickly cooled). The second is to use coldworking equipment (usually a reciprolap) to grind the piece thin after firing. That's labor intensive, but you can reach 1/16" or thinner.

Phil Hoppes · Post by **Phil Hoppes** » Thu Jul 03, 2003 10:41 am

Many have put it to me that glass "wants" to be 6mm or 1/4 inch thick. The scientific explaination is not that it "wants" to be but the surface tension of the material when it is in a liquid form forces it to be this thickness. This surface tension is a function of many things, many of which I don't know but among them I have to believe is the density of the material and the viscosity of the material. Short of molecular engineering or changing the gravitational constant of the earth, you can't do much about the density of the material, but you might be able to affect the viscosity by some type of surface flux as you mention. I'm not aware of any that will do this unfortunately. I know that BE sells 1.5mm clear but I believe that they achieve this by mechanically rolling the glass to that thickness and cooling it before it has a chance to flow back to a thicker state, which is essentially what they do with the 3mm that is their stock in trade. Maybe someone one else on the board here has some experience in this area, although I've not heard of it.

Phil

charlie · Post by **charlie** » Thu Jul 03, 2003 10:45 am

Phil Hoppes wrote:Many have put it to me that glass "wants" to be 6mm or 1/4 inch thick. The scientific explaination is not that it "wants" to be but the surface tension of the material when it is in a liquid form forces it to be this thickness. This surface tension is a function of many things, many of which I don't know but among them I have to believe is the density of the material and the viscosity of the material. Short of molecular engineering or changing the gravitational constant of the earth, you can't do much about the density of the material, but you might be able to affect the viscosity by some type of surface flux as you mention. I'm not aware of any that will do this unfortunately. I know that BE sells 1.5mm clear but I believe that they achieve this by mechanically rolling the glass to that thickness and cooling it before it has a chance to flow back to a thicker state, which is essentially what they do with the 3mm that is their stock in trade. Maybe someone one else on the board here has some experience in this area, although I've not heard of it.

Phil

it's called a surfactant. the hard part would be to find one that's stable at 1500F and won't affect other glass properties, like color for instance.

Paul Tarlow · Post by **Paul Tarlow** » Thu Jul 03, 2003 10:58 am

There was a thread some time ago about "squeezing" glass thinner by putting a second kiln shelf (possible with weights on top) on top of the fusing and having spacers between the two shelves to set the final width.

There was broad disagreement about if it would work or not.

Its on my (very long) list of experiments I want to try. I don't know if anyone ever gave it a shot.

- Paul

Lani McGregor · Post by **Lani McGregor** » Thu Jul 03, 2003 12:07 pm

Paul Tarlow wrote:There was a thread some time ago about "squeezing" glass thinner by putting a second kiln shelf (possible with weights on top) on top of the fusing and having spacers between the two shelves to set the final width.

There was broad disagreement about if it would work or not.

Its on my (very long) list of experiments I want to try. I don't know if anyone ever gave it a shot.

- Paul

Paul,

Before BE ever made its thin glass (1991?) there was a guy (in Washington state, I think) who sent me lots of pretty impressive slides of work done using home-made thin sheets of BE that he said was made this way â€“ heating and pressing 1/8 inch glass between shelves in a kiln. We never tried it, but the slide evidence of his own success with the process seemed valid.

Wish I could remember his nameâ€¦. and now Iâ€™m thinking that it might have been Corvallis, OR and not WAâ€¦. sorryâ€¦. itâ€™s been 15 years or moreâ€¦(I know the name will come to me at 3 amâ€¦. can I call you?)

-Lani

Brock · Post by **Brock** » Thu Jul 03, 2003 12:26 pm

Peter Wendl? Brock

Lani McGregor · Post by **Lani McGregor** » Thu Jul 03, 2003 12:56 pm

Brock wrote:Peter Wendl? Brock

Don't think so. Wasn't Peter the guy who flattened his whole studio? In a fire?

I'm dimly recalling that the guy who flattened the sheets was named Michael something....

REAL dimly,
L

Brock · Post by **Brock** » Thu Jul 03, 2003 12:57 pm

Yes he was, unfortunately. Michael DuPille?
Any more clues . . . sounds like?

Brock

wynpotter · Post by **wynpotter** » Thu Jul 03, 2003 1:47 pm

Well, this is kinda what I was thinking might be the case, gravity works. Thanks for the input. Would putting a weight on top of a piece be a problem when the glass cools at 960 quarts inversion? I'll try with a broken piece of kiln shelf and post later. Thanks wyndham@ac.net

Paul Tarlow · Post by **Paul Tarlow** » Thu Jul 03, 2003 2:44 pm

Lani McGregor wrote:I know the name will come to me at 3 amâ€¦. can I call you?

-Lani

Sure - I'll be babysitting my kiln all weekend and could use the company

- Paul

quill · Post by **quill** » Fri Jul 04, 2003 10:20 am

Funny this would come up.

I have been thinking about this and wondering if mechanically pressing your glass flat, (say with a graphite pad) at fusing temp, letting it reheat enough to get the 'chill' marks out & then cooling would work? Has anyone tried this???

Lani McGregor · Post by **Lani McGregor** » Sun Jul 06, 2003 2:28 am

MICHAEL FOSTER!

....was the guy making his own thin glass about 13 years ago by firing 1/8 inch sheets between two kiln shelves

anyone know him?

...and where was he? Corvallis?

Brock?

Brock · Post by **Brock** » Sun Jul 06, 2003 8:21 am

I can't remember. I tracked him down a few years ago, after seeing his work on the net, and he sent me some slides. Intetresting work, kinda like fairy tale illustrations. Brock

WarmGlass.com

glass thickness ?

glass thickness ?

thanks for the input