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#1
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SLUMPING.
Hello,
I'm a raw beginner with experience so far only of glass painting and the industrial cutting and edgeworking to profile (underwater) of thin LcD type glass. I've collected a great deal of cullet of various colours from bright blue through amber to deep amethyst, and want to slump a largeish (1 metre by 50 cm) glass panel from them. My intention is to lay the various colours of cullet which I've broken into tiny fragments on a sheet of 3mm tinfloat (tin side down) with the various lands of colour separated by long narrow strips of .5 mm LcD glass (which I have). The desired depth of the piece, which is intended to have an interesting rough and knobbly surface, is approximately 10 mm. At a relative's house I have firebricks and several large iron plates from which I can construct a flat oven. There are also a large number of (mainly oak) logs, the intended fuel. Questions; how do I stop the softened cullet from sticking to the backplate? A few little tests I've done with small quantities all stuck to the plate, or picked up so much carbon as to be ruined. How much time should I allow for the cooling cycle? If sand were heaped over the kiln at the end of the firing period, would that slow the cooling enough to prevent the panel from remaining brittle? Are logs, (even hardwood logs) likely to generate the required heat? I'm not after a full melt; I'm merely trying to get the cullet to coalesce, lose it's sharp edges and stick together. I did Google for all this info, but there are so many irrelevant pages with similar titles (but no info) that this posting seemed the only way to find out. Thank you, Designori. |
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#2
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"Des" wrote in message ... Hello, I'm a raw beginner with experience so far only of glass painting and the industrial cutting and edgeworking to profile (underwater) of thin LcD type glass. I've collected a great deal of cullet of various colours from bright blue through amber to deep amethyst, and want to slump a largeish (1 metre by 50 cm) glass panel from them. My intention is to lay the various colours of cullet which I've broken into tiny fragments on a sheet of 3mm tinfloat (tin side down) with the various lands of colour separated by long narrow strips of .5 mm LcD glass (which I have). The desired depth of the piece, which is intended to have an interesting rough and knobbly surface, is approximately 10 mm. At a relative's house I have firebricks and several large iron plates from which I can construct a flat oven. There are also a large number of (mainly oak) logs, the intended fuel. Questions; how do I stop the softened cullet from sticking to the backplate? A few little tests I've done with small quantities all stuck to the plate, or picked up so much carbon as to be ruined. How much time should I allow for the cooling cycle? If sand were heaped over the kiln at the end of the firing period, would that slow the cooling enough to prevent the panel from remaining brittle? Are logs, (even hardwood logs) likely to generate the required heat? I'm not after a full melt; I'm merely trying to get the cullet to coalesce, lose it's sharp edges and stick together. I did Google for all this info, but there are so many irrelevant pages with similar titles (but no info) that this posting seemed the only way to find out. Thank you, Designori. Handle the problems one step at a time. Points being .....glass sticking to mold and mold carbon. Use Stainless steel as a mold and Boron Nitride (Google... zyp products) as a mold separator to prevent sticking. If you use carbon steel, you will have the carbon problem. To use Wood to fire the kiln, you will also need a forced air addition to get the temperature, which will also make the fire wood burn faster, so you will use more fuel(wood) than estimated. In India, coal is regularly used to heat a glass furnace, but forced air is also used to get up to temp. This is theory on my part, never tried to re-invent the wheel, Natural gas always seemed to be there...I used that. How much time should I allow for the cooling cycle? You will probably not be able to hold the temp in an annealing range so the shotgun method will do the trick, you can't over anneal it, so once you hit fuse temp, and start down, remove the heat source(and insulate it somehow , if that means sand, then pile it on thick to keep the loss of heat to a minimum, let it come down 1 1/2 deg per min on thin pieces that should work. You are going to have to test fire a few so you know what your kiln will do and how it acts. Reports of actual results would be appreciated. |
#3
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Use a kiln wash to keep from sticking (available commercially from Bullseye,
Hotline) pretty inexpensive. Biggest problem is that the different types of glass you are using will have different COE (coefficient of expansion) and may cause the piece to crack form the stress caused by each type cooling at different rates. I have no experience with the fuel you mention, Bullseye offers annealing charts regarding cooling schedules and also offers recommended temps to fire to.good luck! m "Des" wrote in message ... Hello, I'm a raw beginner with experience so far only of glass painting and the industrial cutting and edgeworking to profile (underwater) of thin LcD type glass. I've collected a great deal of cullet of various colours from bright blue through amber to deep amethyst, and want to slump a largeish (1 metre by 50 cm) glass panel from them. My intention is to lay the various colours of cullet which I've broken into tiny fragments on a sheet of 3mm tinfloat (tin side down) with the various lands of colour separated by long narrow strips of .5 mm LcD glass (which I have). The desired depth of the piece, which is intended to have an interesting rough and knobbly surface, is approximately 10 mm. At a relative's house I have firebricks and several large iron plates from which I can construct a flat oven. There are also a large number of (mainly oak) logs, the intended fuel. Questions; how do I stop the softened cullet from sticking to the backplate? A few little tests I've done with small quantities all stuck to the plate, or picked up so much carbon as to be ruined. How much time should I allow for the cooling cycle? If sand were heaped over the kiln at the end of the firing period, would that slow the cooling enough to prevent the panel from remaining brittle? Are logs, (even hardwood logs) likely to generate the required heat? I'm not after a full melt; I'm merely trying to get the cullet to coalesce, lose it's sharp edges and stick together. I did Google for all this info, but there are so many irrelevant pages with similar titles (but no info) that this posting seemed the only way to find out. Thank you, Designori. |
#4
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Des wrote:
Hello, I'm a raw beginner with experience so far only of glass painting and the industrial cutting and edgeworking to profile (underwater) of thin LcD type glass. I've collected a great deal of cullet of various colours from bright blue through amber to deep amethyst, and want to slump a largeish (1 metre by 50 cm) glass panel from them. My intention is to lay the various colours of cullet which I've broken into tiny fragments on a sheet of 3mm tinfloat (tin side down) with the various lands of colour separated by long narrow strips of .5 mm LcD glass (which I have). The desired depth of the piece, which is intended to have an interesting rough and knobbly surface, is approximately 10 mm. I have to ask. Is there some reason you believe that the glasses you are attempting to melt together have any chance of staying together? I don't recognize the LcD term, but you mention float. Are the cullet and float compatible? Not really trying to be a smart ass here but if you're trying to mix random glasses together and heat them by burning oak (if you knew the process of getting enough heat from burning wood, you wouldn't have had to ask that question)and end up with a piece 1 x 1/2 Metre (who knows how thick it is, the most important factor) I don't give you much of a chance. It would be something like me hanging out on a board that discusses space travel hoping to put something into orbit soon. Keep us posted. -- Jack Plonked by Native American bobo1148atxmissiondotcom http://photos.yahoo.com/bc/xmissionbobo/ |
#5
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"nJb" wrote in message ... Des wrote: Hello, I'm a raw beginner with experience so far only of glass painting and the industrial cutting and edgeworking to profile (underwater) of thin LcD type glass. I've collected a great deal of cullet of various colours from bright blue through amber to deep amethyst, and want to slump a largeish (1 metre by 50 cm) glass panel from them. My intention is to lay the various colours of cullet which I've broken into tiny fragments on a sheet of 3mm tinfloat (tin side down) with the various lands of colour separated by long narrow strips of .5 mm LcD glass (which I have). The desired depth of the piece, which is intended to have an interesting rough and knobbly surface, is approximately 10 mm. I have to ask. Is there some reason you believe that the glasses you are attempting to melt together have any chance of staying together? I don't recognize the LcD term, but you mention float. Are the cullet and float compatible? Not really trying to be a smart ass here but if you're trying to mix random glasses together and heat them by burning oak (if you knew the process of getting enough heat from burning wood, you wouldn't have had to ask that question)and end up with a piece 1 x 1/2 Metre (who knows how thick it is, the most important factor) I don't give you much of a chance. It would be something like me hanging out on a board that discusses space travel hoping to put something into orbit soon. Keep us posted. Jack Thanks Jack; thinking about it, tackling a piece that big as a first project does seem rather unwise. I simply don't have any pieces of stainless steel that big either. I do have 50cm square pieces. Stainless steel is a pig to work with. My other half just suggested that I might avoid the variation in the expansion of the glasses by firing the individual parts separately to keep the jobs small, then wiring or framing it together. She also suggested that I could avoid the melting process altogether by embedding my cullet in acrylic resin. Well, that wouldn't allow the colours to spread like I wanted them to, and it wouldn't be as permanent a job.By the way, I did mention the desired thickness in my post; I've settled on 10mm. I do have access to no end of calor gas; it just struck me that the logs were there and might be a convenient heat source. I wasn't aware of the fact that they aren't quite enough on their own. H'mmm. Time to stop thinking and do. I'll draw up my moulds for the feature pieces tomorrow (a big 120mm dia orange sun and green and amber leaves mainly) and send for some kilnwash. This sure as hell beats television! Thanks, Des. |
#6
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Des wrote:
Thanks Jack; thinking about it, tackling a piece that big as a first project does seem rather unwise. I simply don't have any pieces of stainless steel that big either. I do have 50cm square pieces. Stainless steel is a pig to work with. Can you get shelf paper where you're at? Ceramic blanket? That would solve the sticking problem for sure. My other half just suggested that I might avoid the variation in the expansion of the glasses by firing the individual parts separately to keep the jobs small, then wiring or framing it together. You don't mention what type of cullet you're using. If it's something made for casting you might be in good shape but may have trouble matching it to the float and the other stuff you're using for strips. She also suggested that I could avoid the melting process altogether by embedding my cullet in acrylic resin. Well, that wouldn't allow the colours to spread like I wanted them to, and it wouldn't be as permanent a job.By the way, I did mention the desired thickness in my post; I've settled on 10mm. Yes you did. My mistake. I do have access to no end of calor gas; it just struck me that the logs were there and might be a convenient heat source. I wasn't aware of the fact that they aren't quite enough on their own. H'mmm. Yes, the wood would need an induced draft to attain and control the heat. Where are you? Isn't there an electric kiln you can use. They seem to work best for glass. Efficient and controllable. Time to stop thinking and do. I'll draw up my moulds for the feature pieces tomorrow (a big 120mm dia orange sun and green and amber leaves mainly) and send for some kilnwash. You would be happy with the ceramic fiber. If the pieces have flat surfaces you wouldn't even need molds. You can fashion the outside walls from 1/16 or 1/8 inch fiber. This sure as hell beats television! Not if there's NHL hockey on. Suggested reading: http://www.warmglass.com/phpBB/index.php The searchable archives are great. Here's a great tutorial: http://www.warmglass.com/basic.htm Good luck. Keep us posted. -- Jack Plonked by Native American bobo1148atxmissiondotcom http://photos.yahoo.com/bc/xmissionbobo/ |
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