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Showing results for tags 'firing ramps'.
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SOfirst time event for old potter. I packed kiln with mugs and bowls. Yes a different glaze but also same clay same ish design old tried and true glaze on half the mugs. some mugs had additions of clay molded pieces attached also. Kiln and scheduled for usual ramping. c 6 firing finishing at 8.30 a.m. one top bung left out. 2 a.m. , I am an old potter used to manually turning up every hour, kiln temp. 480deg. Power out sometime between then and 6.30a.m...no alarm to awaken the sleeping potter..temp 350degC..reprogrammed kiln to go up to 1100 at150C/hr and then usual schedule of 80dc/hr to end and a 15 hold. top bung in. Folk have said it's ok to go this fast , right? I never have before. Result I have12 whole mugs out of 40. rest have a BEAUTIFULLY horizontal crack in middle of handle starting from underside of handle , not quite through the handle so it looks whole from above.Crack is sharp. Second cooling v. slow, finished firing sunday arvo, opened last night. Occurring in both designs and both glazes Bowls crack straight across bottom. ah it's never boring!
My rutile blue glaze (Mastering Cone 6, Glossy Base 1, Variegated Blue) hasn't been variegated since I made the switch from an ancient Econo-kiln to an Easy-Fire. Using records from old firings to program and reprogram the new kiln, I've clearly failed at matching the heat work I achieved with the old Low, Medium, and High settings on my old kiln. Glaze appears grayish and even instead of bright and variegated. I assume the difference is that my old kiln with its small elements was relying more on time than on temperature to get cone 6 down. I'd appreciate any advice for testing that theory without over-firing. I'm guessing that the second-to-last ramp before cooldown would get the kiln to somewhere between 2000F and 2150 at 100 or so per hour. Does that sound reasonable? Can anyone offer an educated guess for the final ramp (speed, target temp., and hold time, if any) to try next?