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Showing results for tags 'oxidation'.
Found 14 results
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This is a problem I have had intermittently since I started making pottery at home in 2010, and lately it seems to be happening to more pieces each firing. 1. Are these pinholes or blisters? Sometimes they are sharp on the edges. 2. How can I correct this? Helpful (?) details: I am doing a slow bisque firing to cone 04. I hold for 10-15 minutes at peak depending how tight I've loaded the kiln. Bisque firing profile: 80/hr to 250F, 200/hr to 1000F, 100/hr to 1100F, 180/hr to 1676F, 80/hr to 1945. Glaze firing to cone 6. I do a programmed "slow" firing on Bartlett controller to 2167F and hold for 15-20 minutes depending on load. Witness cones show cone 6 achieved. Stoneware clay, made by a local manufacturer (all-purpose Goldart-based body rated cone 6 to 8. Contains 4.5% fine grog). 10 cubic foot kiln, electric Kiln is vented with a Vent-a-Kiln hood that is only 2 months old, replaced broken downdraft vent. Problem occurred with both vents. Trouble occurs sporadically with all my glazes, which I mix. The green glaze recipe in example photos: Rutile green: Talc 5, Custer Feldspar 22 Whiting 4 Silica 26 EPK Kaolin 17 Ferro Frit 3134 26 ADD Rutile (light) 6%, Copper Carb 4% Happens on all types of work: mugs, bowls, etc. I've read on the forum about correcting pinholes with a slower bisque but I feel my firing is pretty slow already. Do I need to slow it more? Why does it only happen to certain pieces? Sometimes two identical pieces glazed and fired at the same time in the same way result in one unblemished piece and one as shown above. Working from home on my own and really feeling out of my depth... and incredibly frustrated. -
Hey everyone! I'm in the process of creating a home studio, and I thought it would be a great idea to start making my own glazes. What are some good resources, magazines, or books that have helped you guys when it comes to introductory to advanced glaze making? Also, are there any tips or suggestions when I'm starting out! Thank you so much and any input would be greatly appreciated. -
Good Afternoon, I'm using a Paragon HT22 kiln with the Dwyer gas inlet flow meter. I'm producing small wire springs (stainless steel) that need to be heat treated in order to secure their final form. In my regular smaller kiln, the oxygen in the atmosphere is reacting with the heated stainless steel and results in pretty intense discoloration (brown/dark purple/etc). Using my new kiln with a tank of Nitrogen gas hooked up, I am able to produce springs that have only a slight blue discoloration. This drastic reduction in discoloration/oxidation means that the nitrogen gas is working it's magic, and pushing the vast majority of oxygen out of the kiln, creating an ALMOST perfect inert atmosphere. The question is: IS IT PHYSICALLY POSSIBLE to create a perfectly inert atmosphere in the kiln? Is there something I'm not seeing here? I'm investigating trying to get a higher flow dwyer meter to allow me to pump nitrogen in at a higher rate, but in my gut, I feel like it's not possible. The removal of this blue oxidation requires a chemical bath, which is certainly within my ability to perform, but I'd really rather not. Does anyone have any experience with these gas injected paragon kilns? Any words of wisdom/tips/tricks? Appreciate the help. Kiln on. -
Hey everyone! I recently purchased a used Cress FX27P Electric Kiln, and after bisque firing the first time with the automatic kiln sitter, I noticed that the thumbwheel does not move, and appears to have some sort of malfunction. I figured out a way to bisque firing while moving the thumbwheel manually, but I haven't tried glaze firing yet. Anybody owns this kiln or a similar version of this kiln and can help with how I can glaze fire (cone 6) by moving the thumbwheel myself? For everyone that doesn't know what the purpose of the thumbwheel is, there are numbers 0 to 10 on it, and it moves gradually by itself during a firing. 0 being no power to the elements, and 10 being maximum power to the elements. Any help would be appreciated! Thanks.
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From the album: Glazed Ceramics 2013
This whole bowl was glazed in sun valley. The outside ran quite a bit onto the foot and cookie it was resting on, but the inside result was very interesting. It breaks in a light blue, and can have a whole range of color changes as it melts. In 2013 this was the largest bowl I had managed to throw, it was made out of 10 pounds of clay. Deciding on if I want to use this glaze again on future works, as it is very unpredictable and runny. -
Hello, I have been firing a small gas kiln at the school I teach at and I am finding that about 1/4 of the pots are coming out oxidized, though most of the kiln load is reduced just fine, even with nice reds. Some pots even seem like the clay on the bottom is half reduction color and half oxidation color, which seems odd, and I think that it is causing brittleness in the ware. I am not exactly sure about placement, because another instructor usually unloads the kiln before I can observe it, but I think there is a bubble of full oxidation in this kiln, maybe in the lower left corner. Any ideas? Thanks, James -
From the album: Pottery 2016
Cone 5 B-Mix, carved and glazed in Stoned Denim from Mayco.© Giselle Massey 2016 all rights reserved
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Hi, I am hoping that someone can help me out. I am looking for a cone 10 clear that works well in oxidation, specifically with underglazes, mason stains and color in general. In our studio we have a Laguna Clear and another that work okay in reduction but not well with the colors our students use. I know it can be difficult to have some underglazes come through at cone 10, but, I'm hoping to find a really solid clear that doesn't bubble up, cloud or burn out the color so severely. We use a commercial speedball clear sometimes but it is getting too expensive and I would love to have one clear that can be used in the various kilns. Any recipes/info would be appreciated. Thanks.
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Hi, I have fired black mountain clay in cone 10 reduction w/creamy glaze and love the iron speckles that come through. I see a thread of discussion last year about this w/suggestions. I am looking for any recommendations for creamy glazes (gloss or matt) that would work in electric cone 5/6 (oxidation) that might yield similar results. Any recipes or suggestions would be much appreciated. Thanks in advance! -
Porcelain Vase 10" Fired to cone 6 Oxidation
jim keffer pottery posted a gallery image in Browse Member Galleries
From the album: Jim Keffer Pottery
Porcelain Vase 10" Fired to cone 6 Oxidation with Black Opulence Coyote Blue and Saturation Metalic -
Greetings all, I am trying to create work with a surface quality similar to these tiles by Natalie Blake, http://natalieblakestudios.com/tiles/botanical/ Its sgraffito work in cone 6 oxidation. I am currently using thirds of Frit 3124, EPK, and Iron Oxide for my sgraffito stain on greenware. I could change this although I have already bisqued many pieces with this and it seems like a good recipe that will darken washes/stains that get applied over it. I want to come up with a base recipe or two that will work with as many Mason Stains as possible. I understand that some base recipes do not work with purples but don't know what ingredients to avoid. I've done some testing but would very much appreciate any advice to help me narrow down my testing, or broaden it, I've found information suggesting 1/2 Mason Stain 1/2 Frit 3124, or 1/2 Gerstley Borate works well. Perhaps stained engobes covered in a very thin coating of a Mason stain compatible clear glaze would work well? I saw a video with Natalie spraying the glaze, which makes me wonder if she is using such a 50/50 wash/stain. Although, I was reading that frit 3124 is kinda like its own glaze, so maybe it can appear similar to a typical glaze in the bucket. Do you all have any other ideas of how to get a similar surface quality with as many Mason Stain as possible? What testing would you do if you were trying to get similar results? Thanks anyone for any advice!
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Hi, I am new to the forum and am about to set up my own studio after 30 years of classes. Before I start with the inevitable start up questions, I have an interest in historic ceramics and processes and I wonder if anyone knows the process for creating white salt glazed stoneware like that the British made in the 18th century? Is it just that they did not create a reduction atmosphere so the clay body remained white? The German, British, and American salt glazing process for utilitarian cereamics like jugs usually closed the kiln after adding salt, leading to reduction of the clay body. I understood that one reason for closing the kiln was to help keep the salt fumes in the kiln so the potters would not have to use as much salt. So did the white stoneware potters just use more salt? Any thoughts or who I might contact to get an answer? Thanks in advance. Charles
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I saw this at a craftrs fair and it was fantastic. Has anyone tried this. I just get a bland mauve. What is the secret? Red/Pink Purple/Mauve ^6 Gerstley borate 21 % Nepheline Syenite 16 % Kaolin 11 % Whiting 20 % Silica 32 % Tin 5 % Chrome 0.15%
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I am looking for a good "dark" grey glaze I can fire in oxidation on light stoneware clay. We wire around 1249C (cone 9) This the tone (or shade) of grey I am looking for (forget it's b&w image): Do you have any good recipes? I am thinking about experimenting with white satin glaze I have and adding some black stain I got (Co-Fe-Cr). Am I even on the right track?
