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Showing results for tags 'Reduction firing'.
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Hi, After my graduation I bought a new gas kiln, Rohde TG80 top loading gas kiln downdraft. I have done one test firing but got a bit insecure so I wish to double check. My kiln is fired with Propane. My firing schedule was 200 C/h till 900, then went into reduction till around 1212 C/h after which I failed to keep it in reduction because i started to play to much. Top temperature wa around 1280C. Everything I fire is porcelain unglazed. The top part of the kiln seems ok reduced (not as strong as I wished), but the bottom part not and also lower in temperature. I have read quite some online information and also fired different gas kilns manually before, but not the same as this one. I read different stories about the flames from a reduction firing. Some say orange licking flame is great. But I learned before that a blueish rocket like flame with a bit of orange from the peephole was good as well. I'm a bit confused now. I would like to ask if anyone would like to share some tips and tricks? It would be very helpful. Thank you very much
this is the nice blue flame that shows me the kiln is in reduction, If its yellow it neatral to slightly oxidizing, if its orange red it over reducing , doing a firing with some dark porcealins and chun glazes , Will show when finished
My ignorance is probably getting old, but here is another question from me: What increments in temperature are best when starting to fire. I am dubious about the expertise I've received, and it is as below: My test kiln has been fired once by a technician who came up from the company, and heres what he did: Fired the kiln at 10:13 am. At 10:35 (22 minutes) the temp was up from mid 70s to 335C. 11:15 - 850C 12:45 - 991 1:05 - 1043 1:55 - 1152C 2:20 - 1192 2:25 - 1200C 2:40 - 1223C 2:49 - 1225C 2:50- 3:03 Kept temp stable : 1225-1222. Roughly 14 min. Turned off at 3:03 Temperature at 5:55 was down to 683C From whatever I have read, this was not correct, but the tech was adamant. But, I'd like to correct it, and understand the speed at which the temperature should rise. Some approximation at least. Test Kiln results will differ from the main one. Understood. But the above process didnt seem to start as a 'gentle' one. Even though I understand that the small kiln will reach cone 6 quicker, any suggestions on how to gauge this? Marcia Selsor's advice and John Britt's Charts help a lot, but it would be great if there was some reference for how much time it should take to go from whatever temp the loaded kiln is - 70s, 80s - to getting to the first stage of firing. Just that basic start. When I used the big kiln, we took an hour to simply let the interior 'dry', and then one hour to get to 240C. Then in we lit the second burner, and in twenty minutes we were up from 240 to 463 degrees. Too fast? or OK? That was a bisque firing, but even then, the same tech didnt follow any logical temperature increments. I hope the above makes sense.....?
Hi, I would like to ask a question regarding reduction firing of porcelain. After (some of) my firings there seems to be a thin layer on top of my porcelain objects, which is not very white, more slightly yellowish grey. It very subtle though. But I realised when I sand it for a while it goes off, though this is quite labour intense work. I would like to understand better why this happens. Does someone know if it would be possible to avoid this? I have heard earlier that some ingredients also fired in the kiln might affect the porcelain colour. My reduction firing, was reduction from 950 to 1200 and fired till 1250. In about and around 15 hours. Any tips or information would be very welcome. As I would love to understand the reduction firing process better. Thank you so much!