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tfauchald    0

Hi All,

I'm a high-schooler taking a Ceramics II course, and I love it! I specialize in wheel throwing and I'm really interested in fusing glass on ceramic pieces. How would I do this? My teacher recommended putting marbles in my bowls to melt the glass with the glaze, but I'm curious on what others have to say! Also, where can I either get special glass, or get marbles to melt! Write me back! :)

Thanks,

Travis

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Benzine    610

I've heard of quite a few people doing the marble thing.  I've never tried it myself.  

 

If you are looking for glass marbles, check antique stores, garage sales, or the good ol' internet, at places like Amazon or eBay.  For colored glass pieces, you could check with places, that sell such glass, and you could probably get a deal on the small scraps they have.

 

The problem you'll have with using glass and ceramics together are, that they'll do different things in the kiln.  The glass, clay body and glaze will expand and contract at different rates.  This can lead to some defects.  

 

It's definitely worth exploring, and I'd try some tests first.  In those tests, I'd put the glass material on the inside of the vessel, so that way, any glass bits that might fall/ crack off, or run, don't end up on the kiln shelves.

 

Also, what kind of clay body are you using, what cone are you firing to, and what type of kiln?

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tfauchald    0

I was leaning towards putting glass on the bottoms of vases and bowls! And since I'm still a rookie, i would think about cones 7-10, but honestly i have no clue. I'm using standard clay (whatever that is) and honestly i have absolutely no clue what kind of kiln my professor uses. I will definitely try out the marble technique this upcoming week and i'll get back to you on how it looks with pictures!

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Tyler Miller    331

Something I've always wanted to try, but never have, is to "slump" glass panes over a ceramic bowl and fuse them.  I don't think it would be too difficult to do, just need to make sure the COE's match (or be content with a crazed result).  I don't know if you'd need to follow a glass firing schedule or not.  They can be a little time consuming.

 

Edit:  As a side note, I have slumped glass.  Something important to mention in light of my most recent topic post. ;)

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Jawpot    1
I have never tried marbles.

 

I use colored sheet glass that's made for stained glass windows.  I order from a suppler that sells sheets that are cracked.

 

Soft glass melts / flows around 2400 to 2600*F.  I have never messed with hard glass (hard glass is used in labs and in the kitchen).

 

Most of the time when I use glass I put small peaces on the out side large vases and let them melt down the out side.  I add them to the pots before I glaze with a couple drops of water and a lot of pressure.

 

I have put glass in my ball mill and used it a sieve to sprinkle it over the top of a thin wet glaze.

 

When I first tried working with glass I used a few wine bottles.  The fun of the cuts and not being able to work for a couple days.  When working with glass sheets the edges are more predictable.  Your teacher might have an issue of people getting cut and might limit your glass choices.

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What kind of glass are you using that melts between 2400 and 2600 degrees F? When casting soda-lime glass, 1500 does more than enough... bisque temperatures are certainly above what you'd need to melt the majority of what you'll have access to...

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Benzine    610

I was wondering the same thing Colby. I've started to melt glass bottles, in a campfire, on a couple occasions. The glass wasn't flowing, but I can't imagine it was anywhere near 2400....Closer to 1400 I'd say.

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Pres    896

An adult student used stained glass scraps in the bottom of some bowls, pretty, crazed like crazy, and with sharp edges, but it was an experiment.

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JBaymore    1,432

Remember that some marbles (and other glasses) may potentially contain lead as a flux.

 

best,

 

..............john

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Benzine    610

Remember that some marbles (and other glasses) may potentially contain lead as a flux.

 

best,

 

..............john

So exposure to marbles, can cause you to lose your marbles?

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Jawpot    1

Sorry for the confusion. I posted the melting point of glass not the temp that it runs or that I fire it to.

If you do use glass it will need to cool slowly or you will crack.

 

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Tyler Miller    331

Sorry for the confusion. I posted the melting point of glass not the temp that it runs or that I fire it to.

If you do use glass it will need to cool slowly or you will crack.

What does your firing schedule look like?  I'm specifically curious about whether you need a chill phase to prevent devitrification and what your anneal cycle looks like. 

 

To what temperature are you firing?  I'm curious because this is something I'd genuinely like to try.

 

Doesn't window glass melt around 1800 F?  That's what I learned in my little slumping course.

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Jawpot    1

I fire it to a cone 06 in a gas kiln and then seal the kiln. 3 hours at 150/hr. 4 hours at 300/hr. When I hit 1840F I shut down both burners and seal off the kiln. The slower the better.

I did not have good luck with my electric kilns. They are vented front loaders and have issues sealing up the vent.

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Tyler, devitrification would not occur from cooling too quickly, in fact, cooling too quickly for the crystal structure to arrange is what causes glass to form. A "chill phase" would only cause more of a likelihood for crystal formation in certain situations (an example being crystalline glazes). 

 

Annealing cycles for most soda-lime glasses begin around 900 degrees Fahrenheit. The rate of cooling used is dependent upon the thickness of glass, I could approximate, but would have to look over notes for definite answers. Thin and consistent glass will actually "self-anneal," or cool to room temperature without succumbing to material stress. The critical point at which the glass is most likely to crack during the annealing process is ~700 degrees Fahrenheit for common soda-lime glass... When Jawpot does the slow cool above 1840, I don't see it doing anything for the work (besides lending some good mojo). If he's still achieving successful results, the kiln is actually doing all the work in the annealing process.

 

In the case of interfacing glass and ceramic materials, (as mentioned) the coefficient of expansion (CoE) is a large determining factor of what will work and what won't. BUT at the end of the day, when we have the "crazing talk," there are a lot of potters who don't particularly mind crazing. 

 

In the case of glass+ceramics, more glass in the situation is referred to as an inclusion (of the ceramic material) and the more abundant material (the glass) is more likely to fail. The ceramic material is more resilient, so when the ceramic material is in the greater amount, the glass will still fail (crazing), but the result is a lot more pleasant. Just food for thought...

 

On the note of the OP, just try everything out. Casual science doesn't always produce the best results, but it's always exciting and worthwhile. Don't feel as if you have to fire to c10, but don't feel as if you can't fire to c04 either. The glass will surely melt, so the maturity of the ceramic material should relate to this (meaning fire your body to maturity, so it looks as if it has some "melt" goin' on).

 

I think that's about it... Credentials available upon request!  :P

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schmism    21

here is a vid of someone who put glass in the bottom of a little.... dish?  (i dont know what you call it)  you can see how cracked and crazed it is.

 

 

  @ about 1.50

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Benzine    610

Those are interesting pieces, in that video. She said she fired to Cone 5 right? I didn't think you could use the metal tipped stiilts, above low fire temps, because they'd fuse to the bottom?

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Pres    896

I used metal tipped stilts on pots that were wheel thrown from time to time. I also used them on pieces that were light, like when firing flutes, candle boxes, and other pieces that were a challenge otherwise, or when I would worry about the glaze running and gluing piece to shelf. They will hold up for quite a few firings, but then need to be scrapped when they no longer have the strength to stay up.

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Could it be possible to raku a pot, take it out and fuse some molten glass to it like when blowing glass?

 

Is it just the different coe between the two ceramics that produce the cracking or is there something else helping it become stressed?

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Tyler Miller    331

Tyler, devitrification would not occur from cooling too quickly, in fact, cooling too quickly for the crystal structure to arrange is what causes glass to form. A "chill phase" would only cause more of a likelihood for crystal formation in certain situations (an example being crystalline glazes). 

 

Thanks for the info, Colby!  I think i should have been clearer with the term "chill phase."  I meant a rapid cooling phase, not a hanging out phase.   :)

 

Here's a basic firing schedule for slumping from the book "Warm Glass"  by Beveridge, Domenech, and Pascual.  I got the book after my little course.  Full fusing takes place in a similar temperature range, I think a bit higher, like above 800C, but the cycle's still basically the same.

 

post-61979-0-60861800-1397830719_thumb.jpg

post-61979-0-60861800-1397830719_thumb.jpg

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celica    0

I actually do sculpture and have wanted to fuse glass for some time, I even have a store of glass ready but am unsure how to proceed.  I thought I would bisque and glaze first, as this temperature has to be a lot higher than glass fuses at, then add the glass and just refire to melt stage (about 800c - I'm from Australia), but now realise it may not adhere to glazed clay.  Does it run when you heat it up, or just become jelly-like.  Maybe I have to only place it in crevaces.  Also, if I crush it and apply it, does it become razorsharp, or just rough?  appreciate any help you can give.

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Celica, glass will have different viscosities at different temperatures. If I'm understanding that you're just looking to melt crushed glass onto a glazed surface, you can adhere or temporarily fix the glass to the unfired glaze surface and glaze fire as usual. If you're looking to fuse formed pieces of glass with a glazed surface, you'd likely run into some expansion issues, nothing surmountable, but definitely a bit of a task to work through....

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celica    0

thank you so much.  I dont want to adhere fully formed pieces, just add highlights with crushed glass.  Two other questions: have you any idea what to use to adhere it until it melts, would I use some sort of glue which would burn out and, do I have to lay the piece down so the glass wont run as it melts.

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Venicemud    9

There is a substance that China Painters use called Structure Paste that is used on the surface of glazed objects to provide texture.  This can be applied to the surface of a fired piece and used (before it dries) as "glue" for pieces of glass.  The piece is then fired to around 015 - 018.  I'm sure that the finished piece would not be considered food safe but it can be a very effective addition to ornamental pieces, the outside of vases etc.  Check the gallery Marci Blattenbergers web site, she uses this technique frequently.

 

Joan

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I make spoon rests (small, flat dishes) and melt various bottle glass in them; at cone 6  Brown beer bottles are generally too dark (Shiner seems a little lighter than average), but green generally works great and wine bottles have a whole spectrum of colors.  A couple of notes:

 

1:  It's gonna crackle.  Pretty, but not particularly food-safe.  I wouldn't use if for anything you're going to eat out of.

2:  The inbound color is not necessarily what you end up with.  Sometimes it changes substantially; I saw this a lot with the little glass floral marbles, less so with bottle glass, which is one reason I switched..

3:  Everything I've tried at cone 6 melts pretty thoroughly.  I break up the bottles in a metal bucket with a sledghammer used vertically and get the pieces to under 1/2".  Wear safety glasses and gloves!!!  I store the glass in jars and just pour an appropriate amount from the jar into the piece.  Bigger pieces iof glass are more dangerous, but they all melt into a puddle.

4:  Don't overfill your piece.  Glass on your shelves is bad, very bad, m'kay?.

5:  I generally use a glaze under the glass, usually white.  The glass doeesn't seem to wet the bare clay as well and you can end up with irregular edges to your puddle, which is less attractive.

6:  Using clear glass with a strongly colored glaze underneath can be interesting.  The glass can pick up colorant from the glaze; cobalt is a good example.

7:  Texture under the glass looks great.  Spirals, concentric circles, etc show up well and look great; I generally shoot for about an eighth of an inch deptth.

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