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The pots that I posted pictures of in my cracking platters post were destined to have fused glass decoration. 

I have tried glass by putting a little colored glass in the bottom of a bowl and firing it in a cone six glaze firing. I've gotten some interesting results. I thought it was time to start using a separate cooler glass fusing firing after the glaze firing. Has anyone experimented with this?

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Any glass you put in/on a vessel will craze a lot, to the degree that you can feel the cracks, so it shouldn't be used for food. As for whether it should be done during the glaze firing or after, I think it depends on how hot the glass needs to go to get the degree of melting/running you want, and how your glazes are affected by the second firing. The benefit of firing cooler to melt the glass is that you are ore likely to retain the color of the glass that way. Colored marbles, for instance, tend to burn out most of their color when melted at cone 6, with the exception of  some blues.

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Doc at school we do glass firing with the glaze firing at ^6. Even colored marble. Only as sculptural pieces. Always on horizontal surfaces. 

I believe Mark Hewit does it on green ware i believe, but i am not sure. He is the only guy i know who uses it vertically.

Personally until the science changes i stay away from glass. I look back at history esp. at Persian ceramic history. They never used glass in their clay except at a period of time as their ‘glaze’ surface (powdered glass) before glazing was discovered. Glass was huge in that whole region which came along with the pottery advancements but they never put it together or any other culture for that matter. 

However the potters here used it on their jugs to fix the cracked handles. I dont think they had a separate firing after glaze firing. NOt sure how that worked. 

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I am very anti glass/functional ware combo.

Glaze is not glass. They are related, but the crystalline structure is fundamentally different. The coefficient of expansions are different, and in the case of decorative glass, too far apart to be compatible. It's not a question of if it will fail, but when. Glass shards in food is a bad thing.

It should also be noted that decorave glass fusing and slumping temperatures are FAR lower than most ceramic temperatures. Like at cone 022. If you're firing decorative glass all the way up to cone six, you're boiling it, which explains the colour changes.

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I used to make cute little dishes with glass in the bottom, intended for jewelry use.  But when I had someone tell me they were using it for ketchup and a piece of the glass came out, I stopped doing that!!!  Once someone buys something from you, you have NO control over how they are going to use that piece.  Personally I felt it was a lawsuit waiting to happen.   

Roberta

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try finding Judi Tavill online.   she was working with cone 6 and glass on sculpture but the info was from 2015.    

there is a website that gives very short and useless answers to silly questions.   i think that some of our recent questions reflect the spread of mis-information this way.   the field of ceramics is vast, the short answer to some questions should be "no".

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7 hours ago, docweathers said:

What do you mean by "Personally until the science changes i stay away from glass"?

Ok Doc i hope you dont mind my reply. But i no longer suffer fools.

Glass and clay dont mix. Period. There are a lot of cutesy ceramic glass coasters and stuff people make. (Can’t stand cutesy inane stuff) Ultimately the glass is going to pop out at some point of time. You know like Corporations who are there to make a few bucks. Not to watch out for what’s good for mankind. Businesses  who are putting clay and glass together dont really care for the longevity or safety of their client. They make sure its good for a while so they wont be sued. 

There is nothing wrong in experimenting and discovering what happens. The curious mind should be encouraged. 

When science can discover how to put clay and glass together (a way to never have the glass pieces pop off, whether in a year or 10 years) when there is definite results i will use glass. 

Having said that i can get the glass look. Unfortunately that’s because i have access to a gas kiln which turns the bottom of my Oribe bowls into bright glass like green (if everything is in order and the kiln gods say yes).  Porcelain (and I’m sure white clay body) and transluscent glazes have a glass like look. By glass like look i mean bright colors and the ability to see through the glaze. Even layers of colors. Which you dont get with UG and clear glaze. 

Ceramics is complicated enough, without adding glass to the picture. 

 

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17 hours ago, oldlady said:

try finding Judi Tavill online.   she was working with cone 6 and glass on sculpture but the info was from 2015.    

 

I checked out her website, and I only found one very vague mention that she used (uses?)  glass frit at all, and certainly no how-to or other description. So she has likely updated her website, or just doesn’t share that part of her process now. She might somewhere on social media, but I need to get to work sometime today, so I probably shouldn’t go stalking her just now.

It should be noted that frit used in glassblowing is different than the ones we use for ceramic purposes, and that glass frits are also different than decorative glass, or glass that’s been repurposed. I think that if you know enough about both glass and ceramic materials and you know your chemistry on both of them, it could be possible to find combinations that do indeed work together. That would be the advanced class though.

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17 hours ago, preeta said:

Ok Doc i hope you dont mind my reply. But i no longer suffer fools.

Glass and clay dont mix. Period. There are a lot of cutesy ceramic glass coasters and stuff people make. (Can’t stand cutesy inane stuff) Ultimately the glass is going to pop out at some point of time. You know like Corporations who are there to make a few bucks. Not to watch out for what’s good for mankind. Businesses  who are putting clay and glass together dont really care for the longevity or safety of their client. They make sure its good for a while so they wont be sued. 

There is nothing wrong in experimenting and discovering what happens. The curious mind should be encouraged. 

When science can discover how to put clay and glass together (a way to never have the glass pieces pop off, whether in a year or 10 years) when there is definite results i will use glass. 

Having said that i can get the glass look. Unfortunately that’s because i have access to a gas kiln which turns the bottom of my Oribe bowls into bright glass like green (if everything is in order and the kiln gods say yes).  Porcelain (and I’m sure white clay body) and transluscent glazes have a glass like look. By glass like look i mean bright colors and the ability to see through the glaze. Even layers of colors. Which you dont get with UG and clear glaze. 

Ceramics is complicated enough, without adding glass to the picture. 

 

I am the captain of the "Ship of Fools".

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yes, i noticed that you do not seem to want to improve skills in making good pottery, it seems you would rather experiment on things many of us have discarded as impractical,   

 

 

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COE comes up regularly on here and other forums.  Most of us have enough trouble getting clay and glaze to fit properly, even when purchased from the same supplier and supposedly compatible.

I also work with fused glass and in that community there is a very clear message to NOT mix different COE glass, or to mix any unknown glass.

I'm very firmly in the "don't do it" camp.  You wouldn't put diesel in a petrol-engined car, just to see what happens.  Don't mix glass and ceramics, they don't play well together.

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