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Firing Glass on Clay


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7 hours ago, Marilou said:

I use Bullseye COE 90 very fine grained frit to good result — not on the interior of functional pieces, but wedged into clay, or pooled onto shoulders and edges and on the exterior of pieces.  In test I have done several bowls with glass pooled in the bottom just to test durability — so far even with keys and other items tossed into these bowls, I have no breakage, no shards, no splinters and no blood . 

If there is even the slightest chance of the pot being used for food by someone, in addition to more stringent physical testing you might want to consider getting the pot tested for lead and or cadmium release. From Bullseye there are 51 of their colours that contain more than 1% lead and 47 that more than 0.5% cadmium. COE of glass is multiple times the COE of any claybody, as much as we would like, we can't get away from the laws of physics / thermodynamics. 

Welcome to the forum.


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I'm right there with you on combining  ceramics with other disciplines.  My interest is combining photography onto ceramics. Of course, there are a good handful of folk who have come up with some successful methods on this front.  It does take persistence and testing. 

I applaud your pursuit.  I have not much interest in creating functional ware but always enjoy looking at it. Many here excel at that with centuries worth of experience and wonderful examples to show for it.  Perhaps when you find a spare moment you can post some images of your work.  I imaging I'm not alone in wanting to see what you share.

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I have never seen a glass fuzed to ceramic piece that would be functional and safe. Mug plate etc. Key bowl well thats fine until someone puts cereal in it.

Bullseye as moted above has some nasty stuff in much of the products that make it unsafe for food functionality.Great for sculpture I'm sure-yard art as well.Flower pots ok.

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  • 6 months later...





This thrown pot contains 67% recycled glass and self-glazed at 1700F! 

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That’s a really cool page!

One point I notice, and that the author is also quick to point out, is that incorporating glass cullet into the clay body matrix is different than firing it as a separate layer on top of the piece, because of how mesh size affects melt. At a 50/50 mix of clay and 12 mesh glass grog, it’s the clay particles that wind up acting like aggregate in concrete.

Given that the above website is fro 2007, I wanted to see if any of these products had potentially made it to market. I did find a company that goes one step farther, and uses repurposed aggregate from demolished buildings instead of clay. They’re in New York State.

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