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#1
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Those darned bubbles!
EWWWW!!
I keep getting bubbles on my finished pieces. I have tried up to 40 minutes hold time at 1270 degreess, but they still show up! I am getting rather frustrated by it all. I can "repair" them by adding glaze to the holes (that are more like inverted craters going all the way down to the clay) and refiring once or even twice, but I have a very small kiln at home, and find it both a waste of space and power, while at the same time not wanting to "lose" the pieces. Any ideas on other things I could try? Last kiln was 6 hours to 650, then up to 1270 and hold for 30 minutes. The cooling was over almost a day. Policy being that over about 400, I don't even let the cool air of the laundry room in, but after that, I take out a couple of plugs (top center and bottom) and under 200 I start opening the lid of the kiln a little. That shouldn't affect the bubbles, though, as I am sure they have set at much higher temperatures. BUT - AGH!!! Any input and suggestions greatly appreciated!!! Marianne |
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#2
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Those darned bubbles!
How high are you bisque firing to? What glaze is this happening with (is it
all glazes, just one, a mix)? We need to know more before suggestions would be of much use. 40 minutes of hold time is way more than you should need so something is not as it should be. "Bubbles_" wrote in message ... EWWWW!! I keep getting bubbles on my finished pieces. I have tried up to 40 minutes hold time at 1270 degreess, but they still show up! I am getting rather frustrated by it all. I can "repair" them by adding glaze to the holes (that are more like inverted craters going all the way down to the clay) and refiring once or even twice, but I have a very small kiln at home, and find it both a waste of space and power, while at the same time not wanting to "lose" the pieces. Any ideas on other things I could try? Last kiln was 6 hours to 650, then up to 1270 and hold for 30 minutes. The cooling was over almost a day. Policy being that over about 400, I don't even let the cool air of the laundry room in, but after that, I take out a couple of plugs (top center and bottom) and under 200 I start opening the lid of the kiln a little. That shouldn't affect the bubbles, though, as I am sure they have set at much higher temperatures. BUT - AGH!!! Any input and suggestions greatly appreciated!!! Marianne |
#3
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Those darned bubbles!
Hi DKat! Good to see you!
I am firing bisque to 1050 C. It usually happens with the really glossy glazes, but I actually had one bubble on a matte glaze this time as well. Since the bubbles go all the way in to the clay, do you think I might be bisque firing too low, so that there are "substances" left in the clay before the glaze firing? I do think my oven's thermometer might show a bit higher than it actually is, so maybe just increasing to 1060 or 1070 would help? Once again - any input greatly appreciated! Especially since I have a full load for bisque firing ready. Marianne "DKat" wrote in message ... How high are you bisque firing to? What glaze is this happening with (is it all glazes, just one, a mix)? We need to know more before suggestions would be of much use. 40 minutes of hold time is way more than you should need so something is not as it should be. "Bubbles_" wrote in message ... EWWWW!! I keep getting bubbles on my finished pieces. I have tried up to 40 minutes hold time at 1270 degreess, but they still show up! I am getting rather frustrated by it all. I can "repair" them by adding glaze to the holes (that are more like inverted craters going all the way down to the clay) and refiring once or even twice, but I have a very small kiln at home, and find it both a waste of space and power, while at the same time not wanting to "lose" the pieces. Any ideas on other things I could try? Last kiln was 6 hours to 650, then up to 1270 and hold for 30 minutes. The cooling was over almost a day. Policy being that over about 400, I don't even let the cool air of the laundry room in, but after that, I take out a couple of plugs (top center and bottom) and under 200 I start opening the lid of the kiln a little. That shouldn't affect the bubbles, though, as I am sure they have set at much higher temperatures. BUT - AGH!!! Any input and suggestions greatly appreciated!!! Marianne |
#4
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Those darned bubbles!
Hi Marianne!
I'm home sick with flu and not functioning 100% so bare (or is that bear) with me... First, you should use cones on all firings or at least do regular spot checks. You need to know what heat work you are getting not just what temperature you are going to and you need to know that for different spots of your kiln. You can try bisque firing to cone 04 (1060 C). I only fire to 06 (995 C) and have no problems but I mix my own glazes and know the materials I am working with. Firing to 04 is often recommended. Do you make up your own glazes or are you buying glazes? If you don't fire with cones, see if you can beg, borrow or steal some until you can buy your own, at least to check your next bisque firing. You can get bubbles before if your pot is very, very dry when glazing. I am one of the few potters out on the eastcoast that I know of who rinses off their bisqueware before glazing. It is a really, really quick rinse so the pots are still absorbant. I was taught in the desert environment where it was so dry you could soak your bisqueware in water and five minutes later they would be bone dry. In fact you had to dip them in water or the glaze bubbled up. You can wipe down your pots with a damp sponge to both clean them off and decrease bubbling on the dry glaze surface. This is probably not the problem with your glaze however. It is something you would notice by now. Let us know about the glazes you use. (if you mix your own, what ingredients - better yet what recipe are you using). "Bubbles_" wrote in message ... Hi DKat! Good to see you! I am firing bisque to 1050 C. It usually happens with the really glossy glazes, but I actually had one bubble on a matte glaze this time as well. Since the bubbles go all the way in to the clay, do you think I might be bisque firing too low, so that there are "substances" left in the clay before the glaze firing? I do think my oven's thermometer might show a bit higher than it actually is, so maybe just increasing to 1060 or 1070 would help? Once again - any input greatly appreciated! Especially since I have a full load for bisque firing ready. Marianne "DKat" wrote in message ... How high are you bisque firing to? What glaze is this happening with (is it all glazes, just one, a mix)? We need to know more before suggestions would be of much use. 40 minutes of hold time is way more than you should need so something is not as it should be. "Bubbles_" wrote in message ... EWWWW!! I keep getting bubbles on my finished pieces. I have tried up to 40 minutes hold time at 1270 degreess, but they still show up! I am getting rather frustrated by it all. I can "repair" them by adding glaze to the holes (that are more like inverted craters going all the way down to the clay) and refiring once or even twice, but I have a very small kiln at home, and find it both a waste of space and power, while at the same time not wanting to "lose" the pieces. Any ideas on other things I could try? Last kiln was 6 hours to 650, then up to 1270 and hold for 30 minutes. The cooling was over almost a day. Policy being that over about 400, I don't even let the cool air of the laundry room in, but after that, I take out a couple of plugs (top center and bottom) and under 200 I start opening the lid of the kiln a little. That shouldn't affect the bubbles, though, as I am sure they have set at much higher temperatures. BUT - AGH!!! Any input and suggestions greatly appreciated!!! Marianne |
#5
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Those darned bubbles!
Hey again
Sorry you aren't feeling well! Get well soon! I think it is "bear" - as in to bear a burden, not the animal - hehe! Okay - I haven't even seen anyone using cones over here in Europe - my teacher doesn't even with her new kiln, and neither did an old teacher of mine. I can't remember seeing any in the extensive catalogue from my dealer, either. I was told that sponging off bisque-ware was only to remove the dust. My workshop typically has a humidity of around 50 %. I guess maybe that should be enough. But, when you mention during glazing, I do sometimes se that just little spots aren't covered - like a little speck of grog. I just dab it with my brush with glaze on it, but could that be part of the problem? I like your suggestion of a little quick dip in water, and will try that later on. I need to get myself one of those potter's pencils that doesn't burn away - and start numbering my pots and writing down their whole way through the processes. The clay I use is this: http://www.michel.ch/michel/katalog/...?Redirect=True Apollo Steinzeugton 1000 - 1300°C weiss - hellcrème - hellgrau Westerwälder Steinzeugton ( WM2502 ), sehr fein schamottiert Hervorragender Drehton, sehr plastisch, gute Standfestigkeit, auch für sehr grosse Stücke. Einfach und gut im Trocknen. Guter Glasurträger. Raku möglich. Technische Daten Rohbrand 950 - 980°C Brennbereich 1000 - 1300°C Sintertemperatur 1220°C Brennfarbe weiss - hellcrème - hellgrau Schamottierung 25 % 0 - 0.2 mm Trockenschwindung 5 % 1000°C 1100°C 1200°C 1260°C Brennschwindung 0.5 % 3 % 5 % Wasseraufnahme 14 % 9 % 3 % WAK ( 20 - 500 °C ) 7.2 I'm stuck on translating any of this at the moment, but will try if you don't get the general gist of it. These are the glazes I use. http://www.michel.ch/michel/katalog/...?Redirect=True The one I have most problems with at the moment is 101 with a glaze improver over. The improver - number 100 - makes it go different blues and greens and blacks when I add it on top. Fantastic colors, but the bubbles keep showing up. Mind you, I had a bubble on a matte glaze - 404, I think - on this last high firing. I don't have this problem at all with low-fire stuff - at 1050 C, same as my bisques (that way I can mix them a bit and get a full kiln faster). My kiln is teeny - only about 2 feet wide and maybe 3 feet tall inside - so I wouldn't expect huge temperature ranges inside except when firing with the holes open - on in the lid, one right down at the bottom. possibly even below the bottom shelf. I open those about up to 650 then close them. I can't remember any bubbly piece specifically being by the open holes, and glazes only really start to melt well above 650C, don't they? I'm going to go fire my kiln now. It is a bisque, and I will check my glazes to see if they can be fired higher than 1050 - there are a couple I have that shouldn't be, which is why I have stayed at that temp, and I have some glazed stuff going in now. Thanks again for your time and input! ***virtual chicken soup for you to get better on*** Marianne "DKat" wrote in message ... Hi Marianne! I'm home sick with flu and not functioning 100% so bare (or is that bear) with me... First, you should use cones on all firings or at least do regular spot checks. You need to know what heat work you are getting not just what temperature you are going to and you need to know that for different spots of your kiln. You can try bisque firing to cone 04 (1060 C). I only fire to 06 (995 C) and have no problems but I mix my own glazes and know the materials I am working with. Firing to 04 is often recommended. Do you make up your own glazes or are you buying glazes? If you don't fire with cones, see if you can beg, borrow or steal some until you can buy your own, at least to check your next bisque firing. You can get bubbles before if your pot is very, very dry when glazing. I am one of the few potters out on the eastcoast that I know of who rinses off their bisqueware before glazing. It is a really, really quick rinse so the pots are still absorbant. I was taught in the desert environment where it was so dry you could soak your bisqueware in water and five minutes later they would be bone dry. In fact you had to dip them in water or the glaze bubbled up. You can wipe down your pots with a damp sponge to both clean them off and decrease bubbling on the dry glaze surface. This is probably not the problem with your glaze however. It is something you would notice by now. Let us know about the glazes you use. (if you mix your own, what ingredients - better yet what recipe are you using). "Bubbles_" wrote in message ... Hi DKat! Good to see you! I am firing bisque to 1050 C. It usually happens with the really glossy glazes, but I actually had one bubble on a matte glaze this time as well. Since the bubbles go all the way in to the clay, do you think I might be bisque firing too low, so that there are "substances" left in the clay before the glaze firing? I do think my oven's thermometer might show a bit higher than it actually is, so maybe just increasing to 1060 or 1070 would help? Once again - any input greatly appreciated! Especially since I have a full load for bisque firing ready. Marianne "DKat" wrote in message ... How high are you bisque firing to? What glaze is this happening with (is it all glazes, just one, a mix)? We need to know more before suggestions would be of much use. 40 minutes of hold time is way more than you should need so something is not as it should be. "Bubbles_" wrote in message ... EWWWW!! I keep getting bubbles on my finished pieces. I have tried up to 40 minutes hold time at 1270 degreess, but they still show up! I am getting rather frustrated by it all. I can "repair" them by adding glaze to the holes (that are more like inverted craters going all the way down to the clay) and refiring once or even twice, but I have a very small kiln at home, and find it both a waste of space and power, while at the same time not wanting to "lose" the pieces. Any ideas on other things I could try? Last kiln was 6 hours to 650, then up to 1270 and hold for 30 minutes. The cooling was over almost a day. Policy being that over about 400, I don't even let the cool air of the laundry room in, but after that, I take out a couple of plugs (top center and bottom) and under 200 I start opening the lid of the kiln a little. That shouldn't affect the bubbles, though, as I am sure they have set at much higher temperatures. BUT - AGH!!! Any input and suggestions greatly appreciated!!! Marianne |
#6
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Those darned bubbles!
I'm assuming you are also posting on clayart where you might have more luck
of overlapping with someone using these glazes. With that high of humidity don't dunk the pots (I only rinse mine under the tap very, very quickly). Dunking them is going to empty the air out of them and you don't want that. I would though, wipe them off with a damp sponge. How are you venting your kiln? Clay and glaze materials put off some not good stuff... Since you are buying a commercial glaze material you should be able to call them up and get some support. Since you don't know the ingredients and they do it is their responsiblity to give you help on this. Generally people who sell glazes are all to happy to do all they can to keep their customers happy and buying their product. IMO - There really isn't anything anyone else can do to help unless they are familiar with the glaze or know what it is made up with. As I said a 40 minute soak is to me overkill. Thanks for the chicken soup - it always works. Donna "Bubbles_" wrote in message ... Hey again Sorry you aren't feeling well! Get well soon! I think it is "bear" - as in to bear a burden, not the animal - hehe! Okay - I haven't even seen anyone using cones over here in Europe - my teacher doesn't even with her new kiln, and neither did an old teacher of mine. I can't remember seeing any in the extensive catalogue from my dealer, either. I was told that sponging off bisque-ware was only to remove the dust. My workshop typically has a humidity of around 50 %. I guess maybe that should be enough. But, when you mention during glazing, I do sometimes se that just little spots aren't covered - like a little speck of grog. I just dab it with my brush with glaze on it, but could that be part of the problem? I like your suggestion of a little quick dip in water, and will try that later on. I need to get myself one of those potter's pencils that doesn't burn away - and start numbering my pots and writing down their whole way through the processes. The clay I use is this: http://www.michel.ch/michel/katalog/...?Redirect=True Apollo Steinzeugton 1000 - 1300°C weiss - hellcrème - hellgrau Westerwälder Steinzeugton ( WM2502 ), sehr fein schamottiert Hervorragender Drehton, sehr plastisch, gute Standfestigkeit, auch für sehr grosse Stücke. Einfach und gut im Trocknen. Guter Glasurträger. Raku möglich. Technische Daten Rohbrand 950 - 980°C Brennbereich 1000 - 1300°C Sintertemperatur 1220°C Brennfarbe weiss - hellcrème - hellgrau Schamottierung 25 % 0 - 0.2 mm Trockenschwindung 5 % 1000°C 1100°C 1200°C 1260°C Brennschwindung 0.5 % 3 % 5 % Wasseraufnahme 14 % 9 % 3 % WAK ( 20 - 500 °C ) 7.2 I'm stuck on translating any of this at the moment, but will try if you don't get the general gist of it. These are the glazes I use. http://www.michel.ch/michel/katalog/...?Redirect=True The one I have most problems with at the moment is 101 with a glaze improver over. The improver - number 100 - makes it go different blues and greens and blacks when I add it on top. Fantastic colors, but the bubbles keep showing up. Mind you, I had a bubble on a matte glaze - 404, I think - on this last high firing. I don't have this problem at all with low-fire stuff - at 1050 C, same as my bisques (that way I can mix them a bit and get a full kiln faster). My kiln is teeny - only about 2 feet wide and maybe 3 feet tall inside - so I wouldn't expect huge temperature ranges inside except when firing with the holes open - on in the lid, one right down at the bottom. possibly even below the bottom shelf. I open those about up to 650 then close them. I can't remember any bubbly piece specifically being by the open holes, and glazes only really start to melt well above 650C, don't they? I'm going to go fire my kiln now. It is a bisque, and I will check my glazes to see if they can be fired higher than 1050 - there are a couple I have that shouldn't be, which is why I have stayed at that temp, and I have some glazed stuff going in now. Thanks again for your time and input! ***virtual chicken soup for you to get better on*** Marianne "DKat" wrote in message ... Hi Marianne! I'm home sick with flu and not functioning 100% so bare (or is that bear) with me... First, you should use cones on all firings or at least do regular spot checks. You need to know what heat work you are getting not just what temperature you are going to and you need to know that for different spots of your kiln. You can try bisque firing to cone 04 (1060 C). I only fire to 06 (995 C) and have no problems but I mix my own glazes and know the materials I am working with. Firing to 04 is often recommended. Do you make up your own glazes or are you buying glazes? If you don't fire with cones, see if you can beg, borrow or steal some until you can buy your own, at least to check your next bisque firing. You can get bubbles before if your pot is very, very dry when glazing. I am one of the few potters out on the eastcoast that I know of who rinses off their bisqueware before glazing. It is a really, really quick rinse so the pots are still absorbant. I was taught in the desert environment where it was so dry you could soak your bisqueware in water and five minutes later they would be bone dry. In fact you had to dip them in water or the glaze bubbled up. You can wipe down your pots with a damp sponge to both clean them off and decrease bubbling on the dry glaze surface. This is probably not the problem with your glaze however. It is something you would notice by now. Let us know about the glazes you use. (if you mix your own, what ingredients - better yet what recipe are you using). "Bubbles_" wrote in message ... Hi DKat! Good to see you! I am firing bisque to 1050 C. It usually happens with the really glossy glazes, but I actually had one bubble on a matte glaze this time as well. Since the bubbles go all the way in to the clay, do you think I might be bisque firing too low, so that there are "substances" left in the clay before the glaze firing? I do think my oven's thermometer might show a bit higher than it actually is, so maybe just increasing to 1060 or 1070 would help? Once again - any input greatly appreciated! Especially since I have a full load for bisque firing ready. Marianne "DKat" wrote in message ... How high are you bisque firing to? What glaze is this happening with (is it all glazes, just one, a mix)? We need to know more before suggestions would be of much use. 40 minutes of hold time is way more than you should need so something is not as it should be. "Bubbles_" wrote in message ... EWWWW!! I keep getting bubbles on my finished pieces. I have tried up to 40 minutes hold time at 1270 degreess, but they still show up! I am getting rather frustrated by it all. I can "repair" them by adding glaze to the holes (that are more like inverted craters going all the way down to the clay) and refiring once or even twice, but I have a very small kiln at home, and find it both a waste of space and power, while at the same time not wanting to "lose" the pieces. Any ideas on other things I could try? Last kiln was 6 hours to 650, then up to 1270 and hold for 30 minutes. The cooling was over almost a day. Policy being that over about 400, I don't even let the cool air of the laundry room in, but after that, I take out a couple of plugs (top center and bottom) and under 200 I start opening the lid of the kiln a little. That shouldn't affect the bubbles, though, as I am sure they have set at much higher temperatures. BUT - AGH!!! Any input and suggestions greatly appreciated!!! Marianne |
#7
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Those darned bubbles!
Hi! Hope you are feeling better today!
No, I don't post on clayart. Is that a newsgroup, or a forum? I don't like forums, I keep forgetting to keep up and it ends up that I just drop it. Hmmm - venting my kiln? Well - I told you about the holes. The kiln is in the laundry room, so I make sure there are no clean clothes in the room and then open the window. The room does get warmer, but not too bad. All the glazes I use are so-called "poison class free" - ie. they are supposed to contain no poisonous materials. Still, the room really stinks, especially when I am glaze firing, of course, so I always close the door to the hallway and have the window open in there. There is a hitch with me trying to discuss this with the makers of the glaze, because my German really isn't up to par to discuss this! I tried talking about it with the boss where I buy the stuff, but even face-to-face, I didn't understand everything he said, and it just got so complicated that I gave up. I did catch a couple of ideas, but I thought the gang on here could get into this in general, as it is happening on other glazes than the 101+100 combination, though that one is the worst. Have a lovely day! Marianne "DKat" wrote in message ... I'm assuming you are also posting on clayart where you might have more luck of overlapping with someone using these glazes. With that high of humidity don't dunk the pots (I only rinse mine under the tap very, very quickly). Dunking them is going to empty the air out of them and you don't want that. I would though, wipe them off with a damp sponge. How are you venting your kiln? Clay and glaze materials put off some not good stuff... Since you are buying a commercial glaze material you should be able to call them up and get some support. Since you don't know the ingredients and they do it is their responsiblity to give you help on this. Generally people who sell glazes are all to happy to do all they can to keep their customers happy and buying their product. IMO - There really isn't anything anyone else can do to help unless they are familiar with the glaze or know what it is made up with. As I said a 40 minute soak is to me overkill. Thanks for the chicken soup - it always works. Donna "Bubbles_" wrote in message ... Hey again Sorry you aren't feeling well! Get well soon! I think it is "bear" - as in to bear a burden, not the animal - hehe! Okay - I haven't even seen anyone using cones over here in Europe - my teacher doesn't even with her new kiln, and neither did an old teacher of mine. I can't remember seeing any in the extensive catalogue from my dealer, either. I was told that sponging off bisque-ware was only to remove the dust. My workshop typically has a humidity of around 50 %. I guess maybe that should be enough. But, when you mention during glazing, I do sometimes se that just little spots aren't covered - like a little speck of grog. I just dab it with my brush with glaze on it, but could that be part of the problem? I like your suggestion of a little quick dip in water, and will try that later on. I need to get myself one of those potter's pencils that doesn't burn away - and start numbering my pots and writing down their whole way through the processes. The clay I use is this: http://www.michel.ch/michel/katalog/...?Redirect=True Apollo Steinzeugton 1000 - 1300°C weiss - hellcrème - hellgrau Westerwälder Steinzeugton ( WM2502 ), sehr fein schamottiert Hervorragender Drehton, sehr plastisch, gute Standfestigkeit, auch für sehr grosse Stücke. Einfach und gut im Trocknen. Guter Glasurträger. Raku möglich. Technische Daten Rohbrand 950 - 980°C Brennbereich 1000 - 1300°C Sintertemperatur 1220°C Brennfarbe weiss - hellcrème - hellgrau Schamottierung 25 % 0 - 0.2 mm Trockenschwindung 5 % 1000°C 1100°C 1200°C 1260°C Brennschwindung 0.5 % 3 % 5 % Wasseraufnahme 14 % 9 % 3 % WAK ( 20 - 500 °C ) 7.2 I'm stuck on translating any of this at the moment, but will try if you don't get the general gist of it. These are the glazes I use. http://www.michel.ch/michel/katalog/...?Redirect=True The one I have most problems with at the moment is 101 with a glaze improver over. The improver - number 100 - makes it go different blues and greens and blacks when I add it on top. Fantastic colors, but the bubbles keep showing up. Mind you, I had a bubble on a matte glaze - 404, I think - on this last high firing. I don't have this problem at all with low-fire stuff - at 1050 C, same as my bisques (that way I can mix them a bit and get a full kiln faster). My kiln is teeny - only about 2 feet wide and maybe 3 feet tall inside - so I wouldn't expect huge temperature ranges inside except when firing with the holes open - on in the lid, one right down at the bottom. possibly even below the bottom shelf. I open those about up to 650 then close them. I can't remember any bubbly piece specifically being by the open holes, and glazes only really start to melt well above 650C, don't they? I'm going to go fire my kiln now. It is a bisque, and I will check my glazes to see if they can be fired higher than 1050 - there are a couple I have that shouldn't be, which is why I have stayed at that temp, and I have some glazed stuff going in now. Thanks again for your time and input! ***virtual chicken soup for you to get better on*** Marianne "DKat" wrote in message ... Hi Marianne! I'm home sick with flu and not functioning 100% so bare (or is that bear) with me... First, you should use cones on all firings or at least do regular spot checks. You need to know what heat work you are getting not just what temperature you are going to and you need to know that for different spots of your kiln. You can try bisque firing to cone 04 (1060 C). I only fire to 06 (995 C) and have no problems but I mix my own glazes and know the materials I am working with. Firing to 04 is often recommended. Do you make up your own glazes or are you buying glazes? If you don't fire with cones, see if you can beg, borrow or steal some until you can buy your own, at least to check your next bisque firing. You can get bubbles before if your pot is very, very dry when glazing. I am one of the few potters out on the eastcoast that I know of who rinses off their bisqueware before glazing. It is a really, really quick rinse so the pots are still absorbant. I was taught in the desert environment where it was so dry you could soak your bisqueware in water and five minutes later they would be bone dry. In fact you had to dip them in water or the glaze bubbled up. You can wipe down your pots with a damp sponge to both clean them off and decrease bubbling on the dry glaze surface. This is probably not the problem with your glaze however. It is something you would notice by now. Let us know about the glazes you use. (if you mix your own, what ingredients - better yet what recipe are you using). "Bubbles_" wrote in message ... Hi DKat! Good to see you! I am firing bisque to 1050 C. It usually happens with the really glossy glazes, but I actually had one bubble on a matte glaze this time as well. Since the bubbles go all the way in to the clay, do you think I might be bisque firing too low, so that there are "substances" left in the clay before the glaze firing? I do think my oven's thermometer might show a bit higher than it actually is, so maybe just increasing to 1060 or 1070 would help? Once again - any input greatly appreciated! Especially since I have a full load for bisque firing ready. Marianne "DKat" wrote in message ... How high are you bisque firing to? What glaze is this happening with (is it all glazes, just one, a mix)? We need to know more before suggestions would be of much use. 40 minutes of hold time is way more than you should need so something is not as it should be. "Bubbles_" wrote in message ... EWWWW!! I keep getting bubbles on my finished pieces. I have tried up to 40 minutes hold time at 1270 degreess, but they still show up! I am getting rather frustrated by it all. I can "repair" them by adding glaze to the holes (that are more like inverted craters going all the way down to the clay) and refiring once or even twice, but I have a very small kiln at home, and find it both a waste of space and power, while at the same time not wanting to "lose" the pieces. Any ideas on other things I could try? Last kiln was 6 hours to 650, then up to 1270 and hold for 30 minutes. The cooling was over almost a day. Policy being that over about 400, I don't even let the cool air of the laundry room in, but after that, I take out a couple of plugs (top center and bottom) and under 200 I start opening the lid of the kiln a little. That shouldn't affect the bubbles, though, as I am sure they have set at much higher temperatures. BUT - AGH!!! Any input and suggestions greatly appreciated!!! Marianne |
#8
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Those darned bubbles!
We were fighting bubbles too (not you - them), when we first got into
lowfire clay. It seems that there is some kind of material in the clay that volatilizes at the maturation point, causing holes in the glaze, and bubbles, which are really nasty. The solution, using cone 04 clay and 04 glaze, was to bisque to 04 and hold it there a while in the bisque fire, to let it do its thing. It did make the ware a little less absorbant when glazing, but it beat the bubbles. Andrew Werby www.unitedartworks.com "Bubbles_" wrote in message ... EWWWW!! I keep getting bubbles on my finished pieces. I have tried up to 40 minutes hold time at 1270 degreess, but they still show up! I am getting rather frustrated by it all. I can "repair" them by adding glaze to the holes (that are more like inverted craters going all the way down to the clay) and refiring once or even twice, but I have a very small kiln at home, and find it both a waste of space and power, while at the same time not wanting to "lose" the pieces. Any ideas on other things I could try? Last kiln was 6 hours to 650, then up to 1270 and hold for 30 minutes. The cooling was over almost a day. Policy being that over about 400, I don't even let the cool air of the laundry room in, but after that, I take out a couple of plugs (top center and bottom) and under 200 I start opening the lid of the kiln a little. That shouldn't affect the bubbles, though, as I am sure they have set at much higher temperatures. BUT - AGH!!! Any input and suggestions greatly appreciated!!! Marianne |
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Those darned bubbles!
Hi Andrew :-)
Glad you won't fight me - I'm a wuss! LOL! I am also wondering if the bubbles are coming from the ware itself or from the glaze. Could it be that I have more trouble on the glossy glazes because they just hold the bubbles better? The data on my clay says bisque 950-980 degrees C, and I am already firing it to 1050 (again because then I can combine low-fire glaze and bisque in the same firing). So then I would have thought I have gotten what needs to be gotten out of the clay? The bisque pieces are very nicely absorbant fired to 1050, so I guess I should try 1060 or 1070 on my next batch? *reminder to self - scratching head too much may cause splinters in fingers* Marianne "Andrew Werby" wrote in message . .. We were fighting bubbles too (not you - them), when we first got into lowfire clay. It seems that there is some kind of material in the clay that volatilizes at the maturation point, causing holes in the glaze, and bubbles, which are really nasty. The solution, using cone 04 clay and 04 glaze, was to bisque to 04 and hold it there a while in the bisque fire, to let it do its thing. It did make the ware a little less absorbant when glazing, but it beat the bubbles. Andrew Werby www.unitedartworks.com "Bubbles_" wrote in message ... EWWWW!! I keep getting bubbles on my finished pieces. I have tried up to 40 minutes hold time at 1270 degreess, but they still show up! I am getting rather frustrated by it all. I can "repair" them by adding glaze to the holes (that are more like inverted craters going all the way down to the clay) and refiring once or even twice, but I have a very small kiln at home, and find it both a waste of space and power, while at the same time not wanting to "lose" the pieces. Any ideas on other things I could try? Last kiln was 6 hours to 650, then up to 1270 and hold for 30 minutes. The cooling was over almost a day. Policy being that over about 400, I don't even let the cool air of the laundry room in, but after that, I take out a couple of plugs (top center and bottom) and under 200 I start opening the lid of the kiln a little. That shouldn't affect the bubbles, though, as I am sure they have set at much higher temperatures. BUT - AGH!!! Any input and suggestions greatly appreciated!!! Marianne |
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Those darned bubbles! - A question
Original post below.
I am just wondering about something. My wheel is aluminium, and it oxidizes, so that I get a black stain on the back of my left hand from centering - but I also get it in some of the clay that I later reclaim. Is aluminium a possible cause of these bubbles? Should I stick to new-bought clay and/or treat my wheel with something so it doesn't let off particles? Marianne "Bubbles_" wrote in message ... EWWWW!! I keep getting bubbles on my finished pieces. I have tried up to 40 minutes hold time at 1270 degreess, but they still show up! I am getting rather frustrated by it all. I can "repair" them by adding glaze to the holes (that are more like inverted craters going all the way down to the clay) and refiring once or even twice, but I have a very small kiln at home, and find it both a waste of space and power, while at the same time not wanting to "lose" the pieces. Any ideas on other things I could try? Last kiln was 6 hours to 650, then up to 1270 and hold for 30 minutes. The cooling was over almost a day. Policy being that over about 400, I don't even let the cool air of the laundry room in, but after that, I take out a couple of plugs (top center and bottom) and under 200 I start opening the lid of the kiln a little. That shouldn't affect the bubbles, though, as I am sure they have set at much higher temperatures. BUT - AGH!!! Any input and suggestions greatly appreciated!!! Marianne |
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