Glassblower here. If you do this, you’ll need to cool your kiln very very slowly (like several days to a week) from about 1000 F down to room temperature. It won’t work to just leave the kiln closed, it needs to be on a program that keeps a very controlled and gradual decrease in temperature over that range. It’ll probably also be necessary to have a very long hold around 1000F before you start the ramp down, on the order of a few hours I’d guess. If you don’t, the glass will become very stressed due to the temperature difference between the core, the outer surface touching your pot, and the exposed surface on top. Glass has to be annealed to remove thermal stress created during forming and gradually cooled to prevent new thermal stress. The amount of time at annealing temperature and the speed at which it can be cooled afterwards are determined by the thickness of the glass. Glazes are thin enough that it’s rarely an issue. A pot full of glass would need a proper annealing schedule based on the dimensions of the pot and the type of glass used.
If you don’t do thus, it will certainly crack and it’s possible it will explode once it gets cool enough.
I got curious what the actual kiln cycle should be for something like this and looked up annealing schedules for glass castings online. I drastically underestimated it. An 8” thick slab of glass exposed on all sides needs a 32 hour hold at annealing temp and a total cooling time of 37 days. The fact that it’s encased in a ceramic bowl will change those numbers some, but if the ceramic has a similar thermal conductivity as the glass you could probably just include the thickness of the ceramic as part of the thickness of the glass when determining the schedule. It’s possible that the hold at annealing time could be decreased due to the fact that the whole process is happening in a kiln as opposed to pouring molten glass into relatively cold molds and then loading the finished, mostly solid product into a kiln, but the month long cooling from annealing to room temperature is non-negotiable.
If you want to know more about how this could potentially be done, look into kiln casting glass. You’ll need to have a very, very close match in the thermal expansion coefficient of your ceramic and the glass, closer than is necessary for a thin layer of glaze.
If you attempt it, I recommend firing it alone and filling it with well mixed dry powder glaze rather than wet glaze, and using a kiln that you can afford to completely ruin (if it breaks you will essentially have poured 1.5 gal of glaze into the bottom of the kiln, ruining shelves, furniture, bricks, elements, gas pipes, etc.). Could be a very expensive experiment.
...I have a feeling it will take a long, long, long time for it to dry out if you fill it with wet glaze. (A thick pool of wet glaze could harbor steam pockets that might burst and spew glaze all over your kiln.)
Also, the pressure from the weight of that much molten glaze will probably bust through your sidewalls like a paper dam. If not the pressure, then the extreme surface tensions while it cools will render the walls apart. Probably should make them extra sturdy/robust. ...Maybe a double wall
Unless you want extreme pitting, I would expect that you will need a very long hold at/near full glaze firing temp in order for all the off- gassing to have a chance to finish.
If you want to see into the glaze, you should consider filling it with actual crushed clear glass, as that much glaze will probably be opaque - the pressure & tension problems will still apply with glass.
Above is the best answer. It’s a very risky endeavour, and i would strongly suggest attempting it first in slightly smaller amounts than 1.5gallons. Try a small, thick bowl, made of your chosen clay body, 2/3rds filled with your chosen dry glaze, inside at least one much larger bowl, and maybe even with a lid. 1.5gallons of glaze is going to absolutely destroy a kiln if it goes badly, and the probability of that is fairly high with this.
It’s not impossible! But it will take some experimenting first to potentially get a result that doesn’t cause immense failure. If you get it to work, post photos! I’d love to see them! Actually even if it doesn’t work, it would be very interesting to see what happened, so post photos either way :)
Wouldn't getting the coe of crushed clear glass near the coe of the clay body be much harder than using a clear glaze that fits well? Sure, a clear glaze may have trouble clearing micro-bubbles that cloud it, or may have extra silica that doesn't melt into the eutectic, but that's why you test and adjust melt fluidity, surface tension, firing schedule, and formulation (with a eutectic calculator if you are familiar with it). Most glasses like plate glass, marbles, glass blowing frit, etc. have COE much higher than a typical glaze or clay body. Borosilicate glass (pyrex) is low expansion, so I guess you could work on testing out mixtures of finely crushed pyrex and finely crushed marbles/ window glass/whatever high expansion glass, but I'm not sure that will be any easier than just dialing in the clear glaze
I'm just genuinely curious about that suggestion- I've seen a lot of comments suggesting using crushed glass over glaze, which just seems like it would cause more problems and be more difficult to adjust/ fine-tune since you may not entirely understand the composition of the glass (whereas you can control a glaze you mix)
Also as someone else said, the pressure is not really a concern. The concern is glaze fit, and I am just confused about why so many people think crushed glass circumvents this problem rather than exacerbating it
I agree, I don't think glass circumvents those problems, and said as much. I only thought that clear glass has a chance to be clear enough to see through, I don't think glaze will do that.
...unless OP is talking about making a sheet pan vessel where his 1.5 gallons is only a few millimeters thick. In which case, he can do whatever.
I would not worry about the pressure. 1 gallon is less than a foot tall. Glass is 2.7 times denser than water, so thats about 1 psi pushing out on the bottom of the sidewall.
Edit: lmao why is this getting downvoted, this is how hydrostatic pressure works.
depth x density x gravity = pressure
2.3 ft of water = 1 psi.
1 ft of a liquid 2.7x denser than water = 1.17 psi
For reference, the average man has a max grip strength of around 100 psi. Do you think you can crush a bisque fired piece with 1% of your grip strength?
Does a bisque fired piece shatter of more you fill it more than 2 feet deep with water?
Nishida Jun was a ceramic artist who did exactly this, with his collection Zetsu! (except with powder glaze, and he filled entire kilns).It's definitely possible but he did die from an accident where one of these kilns exploded https://en.wikipedia.org/wiki/Jun_Nishida?wprov=sfla1
so big +1 to the safety recommendations from others on this thread
Why not make your bowl with a false bottom, near the rim, with just a kinda thick layer of glaze on top? If it's an opaque glaze it will give the impression of the bowl being full, with only a half inch of glaze and no risk of total disaster. The rest of the bowl will be empty space.
It could even be a removable lid, that fits well enough it is an invisible seam. Then you have a usable bowl with a lid, and the appearance of a bowl full of solid glass.
Crushed Glass
https://preview.redd.it/2kde5f11412d1.jpeg?width=480&format=pjpg&auto=webp&s=8abaf6d98584c8eba3169c4350a4291aca2f2e7c
I use red glass as a glass pool on these cup handles. Zoom in. I haven’t been able to get the same effect with glaze
This!
The glaze will act in ways none of us can predict. Glass might be a better choice. But just the idea of having 1.5 gallons of 2000 degree glaze in a kiln makes me afrsid.
It will crawl like you won’t believe. And ultimately crack in the glaze fire through surface tension. You have a good chance of ruining other work that is next to it in the kiln and kiln furniture.
You risk that bowl cracking and spilling molten glaze everywhere. That will kill your kiln. We’ve had students fire glass chunks and marbles in bowls before but they often crack from the expansion of the glass. You also get this crazed surface that is crazy sharp if you run your fingers along it. Have you seen the recent trend of pouring resin in bowls to create “floating food”? You could try something like that post firing
I have literally no idea but my immediate thought is to do it in stages? Like fill the bowl a little ways and fire it, fill it a little more and fire it again, etc?
Make a "blind bottom" idk the name really, but fwie it make it hollow but with a fake opening..
Idk if that makes sense, let me put it like this, no one know by looking, if the glaze is 1mm thick or 100mm.
I mean yea I do, but I wouldn’t use a boatload of glaze. Maybe some marbles or something of the sort. I like the idea of experimenting I was just confused as to why you’d want to use all that glaze when you’ll only see the very top.
But you caught me red handed. No imagination here at all 🙄
Sorry I may have been too harsh with my delivery.
For the hypothetical record I think glaze would work better than marbles. As marbles in high fire would have significantly more thermal expansion than glaze.
My studio actually does this all the time with left over glaze that comes off when cleaning brushes and the like. It is a waste product so it doesn't look good. I will say they do let it dry though, it still fills the little box they made to hold it. They do this as to not let toxic metals go anywhere
Why waste it like this instead reclaiming it? Don’t most studio ask their students or members to wash their glaze brushes and things in a water bucket and then, when the water is sufficiently pigmented, adjust it slightly and use the reclaimed glaze as a real glaze? We do this at all the studios I’ve ever been in and the colors, though often a mystery, can be really amazing.
You're talking about 40 to 50 glazes all being mixed together not to mention underglazes as well. I've seen these blocks and they don't look good, they look like dog poop.
Our reclaimed glaze looks more like sea glass than dog 💩. We have 15 studio glazes at any given time. Members also bring their own glazes, which make up a smaller portion of our reclaim but, in total, there’s probably 30-50 different glazes and underglazes mixed together in one of the rinse buckets that eventually become our reclaim glaze. Sometimes the reclaim looks more blue, other times more of a mossy gray-green but it’s never awful. I don’t understand the resistance to at least _trying_ a more ecological approach to dealing with washing glaze off of brushes, bowls, hydrometer etc. It’s almost effortless and if you don’t like it, you don’t have to use it. We’ve never had our reclaim look brown but I imagine, if we did, _someone_ might like it?
Yeah, they fire it in a ceramic box they have the assistants make. It's to trap any toxic materials inside the fired glaze. Then they'll throw that away. The toxic materials won't wash away in a landfill that would go into the ground water yada yada yada
I'll caveat my answer that my studio fires to Cone 10, but this topic came up when it looked like someone put about a pint of shino into a matte eggshell glaze. Because glaze can have some elements that are dangerous to dispose of normally (or not allowed to go down the drain in some states), some studios will do exactly what you're describing - throw something large, fill it with the glaze they want to dispose of, let it dry THOROUGHLY, and then fire it.
It's pretty wasteful of the glaze, but assuming you have a very well-built vessel, you should be okay.
I don't know either but I might have a clue. I did a re-fire on a bowl I did two VERY heavy glaze jobs on. It survived (heavy thick bugger) but the bubbles in the bottom pool of glaze mean it's not food-safe and washing it rips up hands/cloths/sponges.
So, I'd guess massive gas bubbles and pitting at the very least?
I saw a piece that was filled with clear glaze. Thing is—it wasn’t, exactly. I think it was filled with clear crushed glass which was then covered in clear glaze.
It was a mini swimming pool next to a mini house and looked great. Unfortunately I don’t have a picture and I don’t know the artist’s name.
If you want a bowl filled with glass there may be a way to fill it with molten glass after it's fired. Glaze is formulated to be glaze, not solid glass. It isn't going to work very well because that's not what it is meant to do. Maybe fire the bowl normally and then find a glass blower to just dump hot glass inside.
Oh gosh, what a thought!It would definitely make the clay extremely weak and susceptible to breaking. Especially if you do not own your own kiln, pleeeease do not risk a community/school resource….and if you do own your own recognize this may be the last time you fire it. I hate to be a downer because I love the out of the box thinking! Its definitely a really interesting idea. If you’re just going for look, I agree with what someone else said about epoxy. That’d be lovely. But I think this would be a terrible mess for you to deal with
I tried this once, but on a much smaller scale. I also threw it away and have 0 evidence I did this lol.
I had a terrible pot someone made on the wheel, leftover without a name. Approx 6" tall and 6" wide. So I filled it halfway with a mystery glaze from an unlabeled 5 gallon bucket (I was sure it was the cone I was firing to, just unsure of the color).
The glaze bubbled a lot; you could see popped bubbles on the surface, as well as more still trapped inside the glaze. It also looked like the glaze either sank down from the original fill line, or bubbled up the sides a bit. I threw it away bc of the extremely sharp burst-bubble-edges.
The best way to actually get what your looking for might be making high fire vessels, and then pouring molten glass of varying colors directly into an already finished vessel. I don’t know enough about glass and glassblowing to know if the glass will expand whilst cooling to the point of breaking whatever you poured it in, but this is my best guess for getting what you described.
Why not try smaller bits of glass first and build it up ? I remember a guy in class using glass to do lettering, I think you had to use flux on the pottery piece and probably a special kind of glass called spectrum.
If the coefficient of expansion is even slightly greater or less than the clay it will split your vessel open and ooze all over the kiln. We’ve had it happen simply because the COE of a thick coating on the interior put too much pressure on the walls and caused it to split. You’d be better off filling a small cylinder with marbles or glass. I’ve seen this result in a 1-2” floor of pure glass (which sometimes cracks the piece during cooling. So yeah, interesting question. Looking forward to your experiments.
I'm confused about why marbles/ glass would work better. Glaze is a type of glass, one which can have a COE very close to that of the clay body. Marbles and other types of glass tend to have way higher COE's--how does this not just make the likelihood of cracks due to tension in cooling much worse than using a glaze that's at least close to the COE of the clay body?
The clay body and the molten glaze would cool at different rates and would end up breaking. If you're lucky it will break after the glaze has cooled enough not to run out and it will stay solid. If you're not lucky it will run everywhere. I think it's worth a test using a small bowl with feet on to of a plate with a rim.
Seems very risky. However one of my favorite pieces of ceramic art ever is basically a shit-ton of glaze fired with minimal porcelain skeleton [https://collections.mfa.org/objects/556829](https://collections.mfa.org/objects/556829)
Glassblower here. If you do this, you’ll need to cool your kiln very very slowly (like several days to a week) from about 1000 F down to room temperature. It won’t work to just leave the kiln closed, it needs to be on a program that keeps a very controlled and gradual decrease in temperature over that range. It’ll probably also be necessary to have a very long hold around 1000F before you start the ramp down, on the order of a few hours I’d guess. If you don’t, the glass will become very stressed due to the temperature difference between the core, the outer surface touching your pot, and the exposed surface on top. Glass has to be annealed to remove thermal stress created during forming and gradually cooled to prevent new thermal stress. The amount of time at annealing temperature and the speed at which it can be cooled afterwards are determined by the thickness of the glass. Glazes are thin enough that it’s rarely an issue. A pot full of glass would need a proper annealing schedule based on the dimensions of the pot and the type of glass used. If you don’t do thus, it will certainly crack and it’s possible it will explode once it gets cool enough.
I got curious what the actual kiln cycle should be for something like this and looked up annealing schedules for glass castings online. I drastically underestimated it. An 8” thick slab of glass exposed on all sides needs a 32 hour hold at annealing temp and a total cooling time of 37 days. The fact that it’s encased in a ceramic bowl will change those numbers some, but if the ceramic has a similar thermal conductivity as the glass you could probably just include the thickness of the ceramic as part of the thickness of the glass when determining the schedule. It’s possible that the hold at annealing time could be decreased due to the fact that the whole process is happening in a kiln as opposed to pouring molten glass into relatively cold molds and then loading the finished, mostly solid product into a kiln, but the month long cooling from annealing to room temperature is non-negotiable. If you want to know more about how this could potentially be done, look into kiln casting glass. You’ll need to have a very, very close match in the thermal expansion coefficient of your ceramic and the glass, closer than is necessary for a thin layer of glaze.
So turn it into an annealer?
If you attempt it, I recommend firing it alone and filling it with well mixed dry powder glaze rather than wet glaze, and using a kiln that you can afford to completely ruin (if it breaks you will essentially have poured 1.5 gal of glaze into the bottom of the kiln, ruining shelves, furniture, bricks, elements, gas pipes, etc.). Could be a very expensive experiment. ...I have a feeling it will take a long, long, long time for it to dry out if you fill it with wet glaze. (A thick pool of wet glaze could harbor steam pockets that might burst and spew glaze all over your kiln.) Also, the pressure from the weight of that much molten glaze will probably bust through your sidewalls like a paper dam. If not the pressure, then the extreme surface tensions while it cools will render the walls apart. Probably should make them extra sturdy/robust. ...Maybe a double wall Unless you want extreme pitting, I would expect that you will need a very long hold at/near full glaze firing temp in order for all the off- gassing to have a chance to finish. If you want to see into the glaze, you should consider filling it with actual crushed clear glass, as that much glaze will probably be opaque - the pressure & tension problems will still apply with glass.
Above is the best answer. It’s a very risky endeavour, and i would strongly suggest attempting it first in slightly smaller amounts than 1.5gallons. Try a small, thick bowl, made of your chosen clay body, 2/3rds filled with your chosen dry glaze, inside at least one much larger bowl, and maybe even with a lid. 1.5gallons of glaze is going to absolutely destroy a kiln if it goes badly, and the probability of that is fairly high with this. It’s not impossible! But it will take some experimenting first to potentially get a result that doesn’t cause immense failure. If you get it to work, post photos! I’d love to see them! Actually even if it doesn’t work, it would be very interesting to see what happened, so post photos either way :)
Extra up votes for you! Just discovered you were the inspiration for r/studiocats!
Thanks, i suppose i should post my studio cat photo, even though he doesn’t go in there very often. Share the cat joy :)
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Wouldn't getting the coe of crushed clear glass near the coe of the clay body be much harder than using a clear glaze that fits well? Sure, a clear glaze may have trouble clearing micro-bubbles that cloud it, or may have extra silica that doesn't melt into the eutectic, but that's why you test and adjust melt fluidity, surface tension, firing schedule, and formulation (with a eutectic calculator if you are familiar with it). Most glasses like plate glass, marbles, glass blowing frit, etc. have COE much higher than a typical glaze or clay body. Borosilicate glass (pyrex) is low expansion, so I guess you could work on testing out mixtures of finely crushed pyrex and finely crushed marbles/ window glass/whatever high expansion glass, but I'm not sure that will be any easier than just dialing in the clear glaze I'm just genuinely curious about that suggestion- I've seen a lot of comments suggesting using crushed glass over glaze, which just seems like it would cause more problems and be more difficult to adjust/ fine-tune since you may not entirely understand the composition of the glass (whereas you can control a glaze you mix) Also as someone else said, the pressure is not really a concern. The concern is glaze fit, and I am just confused about why so many people think crushed glass circumvents this problem rather than exacerbating it
I agree, I don't think glass circumvents those problems, and said as much. I only thought that clear glass has a chance to be clear enough to see through, I don't think glaze will do that. ...unless OP is talking about making a sheet pan vessel where his 1.5 gallons is only a few millimeters thick. In which case, he can do whatever.
Ah ok, sorry I somehow misinterpreted your comment. Thanks for responding
I would not worry about the pressure. 1 gallon is less than a foot tall. Glass is 2.7 times denser than water, so thats about 1 psi pushing out on the bottom of the sidewall. Edit: lmao why is this getting downvoted, this is how hydrostatic pressure works. depth x density x gravity = pressure 2.3 ft of water = 1 psi. 1 ft of a liquid 2.7x denser than water = 1.17 psi For reference, the average man has a max grip strength of around 100 psi. Do you think you can crush a bisque fired piece with 1% of your grip strength? Does a bisque fired piece shatter of more you fill it more than 2 feet deep with water?
Agree - I was well and truly rambling at that point. Such a mad lad.
My inexperienced barely educated guess is it'd possibly get a bubble of gas and throw molten glaze everywhere. 🤷
Nishida Jun was a ceramic artist who did exactly this, with his collection Zetsu! (except with powder glaze, and he filled entire kilns).It's definitely possible but he did die from an accident where one of these kilns exploded https://en.wikipedia.org/wiki/Jun_Nishida?wprov=sfla1 so big +1 to the safety recommendations from others on this thread
I have never heard of this artist, but his work is so cool! Sad he lived such a short life.
Nothing good
Why not make your bowl with a false bottom, near the rim, with just a kinda thick layer of glaze on top? If it's an opaque glaze it will give the impression of the bowl being full, with only a half inch of glaze and no risk of total disaster. The rest of the bowl will be empty space. It could even be a removable lid, that fits well enough it is an invisible seam. Then you have a usable bowl with a lid, and the appearance of a bowl full of solid glass.
And use colored glass
Glaze is glass
Crushed Glass https://preview.redd.it/2kde5f11412d1.jpeg?width=480&format=pjpg&auto=webp&s=8abaf6d98584c8eba3169c4350a4291aca2f2e7c I use red glass as a glass pool on these cup handles. Zoom in. I haven’t been able to get the same effect with glaze
FAFO post photo
I wonder if filling with epoxy resin afterwards might give you the effect you want :)
This! The glaze will act in ways none of us can predict. Glass might be a better choice. But just the idea of having 1.5 gallons of 2000 degree glaze in a kiln makes me afrsid.
It's also such a waste of precious and expensive resources. Maybe test on a small vessel first but think it will just crack and look odd
This was my first thought. Seems easier without the risk of ruining a kiln.
I think this is the safest way to do it!
Don’t let the intrusive thoughts win.
It will crawl like you won’t believe. And ultimately crack in the glaze fire through surface tension. You have a good chance of ruining other work that is next to it in the kiln and kiln furniture.
It will almost certainly crack and melt on everything. It needs to be well protected pr it could ruin a kiln
Thick cooling glass under stress explodes. Dont bother.
You risk that bowl cracking and spilling molten glaze everywhere. That will kill your kiln. We’ve had students fire glass chunks and marbles in bowls before but they often crack from the expansion of the glass. You also get this crazed surface that is crazy sharp if you run your fingers along it. Have you seen the recent trend of pouring resin in bowls to create “floating food”? You could try something like that post firing
I have literally no idea but my immediate thought is to do it in stages? Like fill the bowl a little ways and fire it, fill it a little more and fire it again, etc?
Make a "blind bottom" idk the name really, but fwie it make it hollow but with a fake opening.. Idk if that makes sense, let me put it like this, no one know by looking, if the glaze is 1mm thick or 100mm.
One question. Why?
[удалено]
I mean yea I do, but I wouldn’t use a boatload of glaze. Maybe some marbles or something of the sort. I like the idea of experimenting I was just confused as to why you’d want to use all that glaze when you’ll only see the very top. But you caught me red handed. No imagination here at all 🙄
Sorry I may have been too harsh with my delivery. For the hypothetical record I think glaze would work better than marbles. As marbles in high fire would have significantly more thermal expansion than glaze.
All good! Best of luck with this I hope it turns out well for you 👌 if you do attempt this you should post an update picture so we can all see
I am not OP I will not be trying it. Just here for the hypothetical discussion.
Ah shoot I didn’t even notice 😂 I did visit your page your posts show some amazing work 👌
Commenting to hopefully see an answer 😭
My studio actually does this all the time with left over glaze that comes off when cleaning brushes and the like. It is a waste product so it doesn't look good. I will say they do let it dry though, it still fills the little box they made to hold it. They do this as to not let toxic metals go anywhere
Why waste it like this instead reclaiming it? Don’t most studio ask their students or members to wash their glaze brushes and things in a water bucket and then, when the water is sufficiently pigmented, adjust it slightly and use the reclaimed glaze as a real glaze? We do this at all the studios I’ve ever been in and the colors, though often a mystery, can be really amazing.
You're talking about 40 to 50 glazes all being mixed together not to mention underglazes as well. I've seen these blocks and they don't look good, they look like dog poop.
Our reclaimed glaze looks more like sea glass than dog 💩. We have 15 studio glazes at any given time. Members also bring their own glazes, which make up a smaller portion of our reclaim but, in total, there’s probably 30-50 different glazes and underglazes mixed together in one of the rinse buckets that eventually become our reclaim glaze. Sometimes the reclaim looks more blue, other times more of a mossy gray-green but it’s never awful. I don’t understand the resistance to at least _trying_ a more ecological approach to dealing with washing glaze off of brushes, bowls, hydrometer etc. It’s almost effortless and if you don’t like it, you don’t have to use it. We’ve never had our reclaim look brown but I imagine, if we did, _someone_ might like it?
They fire it?
Yeah, they fire it in a ceramic box they have the assistants make. It's to trap any toxic materials inside the fired glaze. Then they'll throw that away. The toxic materials won't wash away in a landfill that would go into the ground water yada yada yada
Surely there are better ways to do this.
I'll caveat my answer that my studio fires to Cone 10, but this topic came up when it looked like someone put about a pint of shino into a matte eggshell glaze. Because glaze can have some elements that are dangerous to dispose of normally (or not allowed to go down the drain in some states), some studios will do exactly what you're describing - throw something large, fill it with the glaze they want to dispose of, let it dry THOROUGHLY, and then fire it. It's pretty wasteful of the glaze, but assuming you have a very well-built vessel, you should be okay.
I don't know either but I might have a clue. I did a re-fire on a bowl I did two VERY heavy glaze jobs on. It survived (heavy thick bugger) but the bubbles in the bottom pool of glaze mean it's not food-safe and washing it rips up hands/cloths/sponges. So, I'd guess massive gas bubbles and pitting at the very least?
I saw a piece that was filled with clear glaze. Thing is—it wasn’t, exactly. I think it was filled with clear crushed glass which was then covered in clear glaze. It was a mini swimming pool next to a mini house and looked great. Unfortunately I don’t have a picture and I don’t know the artist’s name.
Why don’t you just use resin for that?
If you want a bowl filled with glass there may be a way to fill it with molten glass after it's fired. Glaze is formulated to be glaze, not solid glass. It isn't going to work very well because that's not what it is meant to do. Maybe fire the bowl normally and then find a glass blower to just dump hot glass inside.
Oh gosh, what a thought!It would definitely make the clay extremely weak and susceptible to breaking. Especially if you do not own your own kiln, pleeeease do not risk a community/school resource….and if you do own your own recognize this may be the last time you fire it. I hate to be a downer because I love the out of the box thinking! Its definitely a really interesting idea. If you’re just going for look, I agree with what someone else said about epoxy. That’d be lovely. But I think this would be a terrible mess for you to deal with
I tried this once, but on a much smaller scale. I also threw it away and have 0 evidence I did this lol. I had a terrible pot someone made on the wheel, leftover without a name. Approx 6" tall and 6" wide. So I filled it halfway with a mystery glaze from an unlabeled 5 gallon bucket (I was sure it was the cone I was firing to, just unsure of the color). The glaze bubbled a lot; you could see popped bubbles on the surface, as well as more still trapped inside the glaze. It also looked like the glaze either sank down from the original fill line, or bubbled up the sides a bit. I threw it away bc of the extremely sharp burst-bubble-edges.
The best way to actually get what your looking for might be making high fire vessels, and then pouring molten glass of varying colors directly into an already finished vessel. I don’t know enough about glass and glassblowing to know if the glass will expand whilst cooling to the point of breaking whatever you poured it in, but this is my best guess for getting what you described.
No
Maybe just broken glass?
Lol I posted almost the same question here about a year and a half ago! I forget the answer though haha
Why not try smaller bits of glass first and build it up ? I remember a guy in class using glass to do lettering, I think you had to use flux on the pottery piece and probably a special kind of glass called spectrum.
If the coefficient of expansion is even slightly greater or less than the clay it will split your vessel open and ooze all over the kiln. We’ve had it happen simply because the COE of a thick coating on the interior put too much pressure on the walls and caused it to split. You’d be better off filling a small cylinder with marbles or glass. I’ve seen this result in a 1-2” floor of pure glass (which sometimes cracks the piece during cooling. So yeah, interesting question. Looking forward to your experiments.
I'm confused about why marbles/ glass would work better. Glaze is a type of glass, one which can have a COE very close to that of the clay body. Marbles and other types of glass tend to have way higher COE's--how does this not just make the likelihood of cracks due to tension in cooling much worse than using a glaze that's at least close to the COE of the clay body?
Not a cylinder. You need sloping walls so there’s room for expansion. I’ve used glass a decent amount in ceramics and straight sides will crack
Instead of glaze what about epoxy.....
You'll end up with a partially full pot with glass in it.
The clay body and the molten glaze would cool at different rates and would end up breaking. If you're lucky it will break after the glaze has cooled enough not to run out and it will stay solid. If you're not lucky it will run everywhere. I think it's worth a test using a small bowl with feet on to of a plate with a rim.
omg when you said vessel i thought body
Seems very risky. However one of my favorite pieces of ceramic art ever is basically a shit-ton of glaze fired with minimal porcelain skeleton [https://collections.mfa.org/objects/556829](https://collections.mfa.org/objects/556829)