Hi, I am new to this site and new to glass but have 30 years experience as a Univ. Sculptor. I am about to start kiln casting and have prepared several waxes for ceramic shell burnout. I plan to start using the flower pot drip method and will be firing in an 8 or 9 cubic foot top loading Amaco with side elements only. The kiln is controled by a GB4. I plan to use either Bullseye or Uroboros billit. The waxes are approximately 3"X8"X12" My questions are:
-Should I load the kiln tight?
-Should I use insulating or hard bricks for the mold and flower pot supports?
-Can I peek in to see progress or add glass?
-Can you kiln cast several pieces of different sizes in the same firing?
-I haven't purchased the glass yet, Bullseye or Eroboros or other?
- Eventually I will frit cast, can I also billit cast in the same firing?
- Is there an annealing schedule I could follow?
-The thermocouple will read the atmosphere, when using shell molds do you need to compensate in some way to figure glass temp?
I know these are elementary questions but will appreciate any response to any of them.
Ted Metz
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virgin kiln caster has some questions
Moderator: Brad Walker
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jerry flanary
- Posts: 158
- Joined: Tue Sep 09, 2003 11:11 pm
- Location: norfolk, va
ceramic shell burnout! Are you casting w/ Mold Mix 6/ Zircar?
-Should I load the kiln tight? Pack it loosly at first, every kiln is different. I think it really depends on how much juice you got.
-Should I use insulating or hard bricks for the mold and flower pot supports? Insulating bricks are a smaller thermal mass to heat up.
-Can I peek in to see progress or add glass? Hell yes.
-Can you kiln cast several pieces of different sizes in the same firing? Yes but anneal the whole load for the biggest piece in there.
-I haven't purchased the glass yet, Bullseye or Eroboros or other? Are you going to mix colors in the same piece? Yes- Bullseye. Why not Gaffer?
- Eventually I will frit cast, can I also billit cast in the same firing? I don't have personal experience but I would expect one visual texture/effect in the frit section and another in the billeted.
- Is there an annealing schedule I could follow? Yes, maybe check the archive.
-The thermocouple will read the atmosphere, when using shell molds do you need to compensate in some way to figure glass temp? I think people just learn how things go in their kiln based on air temps. Maybe try a firing w/ one or two pieces for the first couple of times to get your feet wet. Then if you have a failure it's not such a huge failure.
j.
-Should I load the kiln tight? Pack it loosly at first, every kiln is different. I think it really depends on how much juice you got.
-Should I use insulating or hard bricks for the mold and flower pot supports? Insulating bricks are a smaller thermal mass to heat up.
-Can I peek in to see progress or add glass? Hell yes.
-Can you kiln cast several pieces of different sizes in the same firing? Yes but anneal the whole load for the biggest piece in there.
-I haven't purchased the glass yet, Bullseye or Eroboros or other? Are you going to mix colors in the same piece? Yes- Bullseye. Why not Gaffer?
- Eventually I will frit cast, can I also billit cast in the same firing? I don't have personal experience but I would expect one visual texture/effect in the frit section and another in the billeted.
- Is there an annealing schedule I could follow? Yes, maybe check the archive.
-The thermocouple will read the atmosphere, when using shell molds do you need to compensate in some way to figure glass temp? I think people just learn how things go in their kiln based on air temps. Maybe try a firing w/ one or two pieces for the first couple of times to get your feet wet. Then if you have a failure it's not such a huge failure.
j.
Thanks Jerry, that is helpful information. I am going to use mold mix 6 on some of he waxes but I was going to use my ceramic shell slurry for bronze casting on the majority or them.
I see that you are in Norfolk, I graduated from ODC (now U) in 1971.
I promise to have tougher questions in the future. Thank you, Ted
I see that you are in Norfolk, I graduated from ODC (now U) in 1971.
I promise to have tougher questions in the future. Thank you, Ted
Ted, I do not have a lot of experience in kiln casting but I think you might want to try a small casting using your ceramic shell slurry for bronze casting with the glass you decide to use in your large casting. Half and half plaser/silica flour is the classic investment for glass casting in the kiln. I question how the glass will react with and stick to your ceramic slurry. Also, I wonder how hard the ceramic slurry will be to remove from the glass safely. Perhaps one technique would be to apply a splash coat of the plaster-silica investment to your model then use your ceramic slurry for the balance of the mold. Again, try a small item before going to production sized casts.
Best wishes,
Tom in Texas
Best wishes,
Tom in Texas
Not from personal exp!!!
The prob I've "heard" of with ceramic shell is removal. Evidently it can be tougher than the glass...
Also as a first time use of the ceramic shell(unless you know the recipe is OK for glass) I would mount the mold in a bucket of sand/similar in case it does not hold up. Cleaning glass off of elemnets is not fun.
Good Luck
Greg
Oh you should probably invest in Glass as an artists medium by Lucartha (something). It goes over some nice basics and some advanced stuff.
The prob I've "heard" of with ceramic shell is removal. Evidently it can be tougher than the glass...
Also as a first time use of the ceramic shell(unless you know the recipe is OK for glass) I would mount the mold in a bucket of sand/similar in case it does not hold up. Cleaning glass off of elemnets is not fun.
Good Luck
Greg
Oh you should probably invest in Glass as an artists medium by Lucartha (something). It goes over some nice basics and some advanced stuff.
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John Kurman
- Posts: 32
- Joined: Wed Apr 23, 2003 8:38 am
- Location: Chicago, IL
- Contact:
Ted,
Yes, cermaic shell has been used, and used successfully for casting glass, but as someone who has used ceramic shell (both for bronze and glass), I suggest you save yourself a universe of trouble and use the ceramic shell only as a sagger exterior coat to hold large castings together. True, ceramic shell is inert in contact with cast glass, but it is incredibly tough. I ended up using a boxcutter blade between glass and shell and flicking small pieces of the shell off. And you may have to sandblast as well - depending on the cast.
Half-n-half plaster/silica is so much more easily removed. If you intend to use ceramic shell, have a fun couple of weeks getting the shell off the glass - and start practicing zenlike detachment and patience now.
Yes, cermaic shell has been used, and used successfully for casting glass, but as someone who has used ceramic shell (both for bronze and glass), I suggest you save yourself a universe of trouble and use the ceramic shell only as a sagger exterior coat to hold large castings together. True, ceramic shell is inert in contact with cast glass, but it is incredibly tough. I ended up using a boxcutter blade between glass and shell and flicking small pieces of the shell off. And you may have to sandblast as well - depending on the cast.
Half-n-half plaster/silica is so much more easily removed. If you intend to use ceramic shell, have a fun couple of weeks getting the shell off the glass - and start practicing zenlike detachment and patience now.
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Erik Brown
Thank you all for the information and advice. I will back off the plan to invest with shell and try the plaster/ silica. What about Mold Mix 6? Is that not similar to a ceramic shell coating? Is mold mix 6 an advisable kiln casting material? I know it is expensive but I figure I should try all the options. I did just get the book "Glass An Artist's Medium" Thanks again.
Ted
Ted
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jerry flanary
- Posts: 158
- Joined: Tue Sep 09, 2003 11:11 pm
- Location: norfolk, va
Perhaps one technique would be to apply a splash coat of the plaster-silica investment to your model then use your ceramic slurry for the balance of the mold. Again, try a small item before going to production sized casts.
This sounds like a beautiful idea, Tom.
I was wondering the same approach but w/ zircar backed up w slurry. One possible problem w/ my idea though is that zircar is water based so maybe slurry isn't the way to go....
For a release you might also try swishing kiln wash into the still-hot-from-burnout shells. I have heard that hotline works good for this. I've even seen the good results. Just haven't been able to duplicate it yet.
I've also heard that leaded glass w/ zircar leaves a cleaner surface- lower melting point thing...
j.
This sounds like a beautiful idea, Tom.
I was wondering the same approach but w/ zircar backed up w slurry. One possible problem w/ my idea though is that zircar is water based so maybe slurry isn't the way to go....
For a release you might also try swishing kiln wash into the still-hot-from-burnout shells. I have heard that hotline works good for this. I've even seen the good results. Just haven't been able to duplicate it yet.
I've also heard that leaded glass w/ zircar leaves a cleaner surface- lower melting point thing...
j.