Limagirl Posted January 8, 2015 Report Share Posted January 8, 2015 Hello potters, I am gearing up to do my first bisque fire. I use stoneware clay bodies and a raku clay. I have been doing enormous amounts of research and did get help at my local clay store. My questions are: Can I bisque the stoneware and raku clay bodies in the same bisque fire? I am not feeling confident with the hold temps. I am very fearful that the temps will increase too fast and my posts will explode. I have attached a picture of the front of my kiln. I am going to bisque at a cone 05. Any advise would be greatly appreciated. Link to comment Share on other sites More sharing options...
bciskepottery Posted January 8, 2015 Report Share Posted January 8, 2015 You should have no problems bisquing your stoneware and raku clay bodies in the same bisque fire. Holding temperature in a manual (non-computer controlled) kiln is difficult without a pyrometer that also provides temperature readings from inside the kiln. You could monitor your kiln and when the kiln cuts off after the cone bends in the sitter, and then manually keep the kiln on for another 5 minutes and then turn it off. That long of a hold will not cause pots to explode. On the inside, use cone packs -- for bisque, cones for 04, 05, 06 -- on the bottom, middle, and top shelves; these will help you get a sense of how even your kiln is firing and where the hot/cold spots are. Ramping up the temperature slowly from the start avoids posts exploding or cracking, etc (either due to wall thickness, water/steam, or dampness); increasing temperature too fast at the beginning is more likely to cause problems. A common firing schedule is 2 hours low, 2 hours medium, then turn up to high until you reach your desired cone. If you know another potter with a kiln, invite them over to help you during your first firing. Link to comment Share on other sites More sharing options...
smallshop Posted January 8, 2015 Report Share Posted January 8, 2015 Limagirl, I have a couple of older kilns very similar to yours. They are easy to fire but require you to remember to adjust the temperature. If I think there is any possibility of moisture in my pots I usually prop the lid open an inch or two with a stilt or firebrick chunk, leave all peephole plugs out and fire at the lowest setting for 3-4 hours. Then with the lid closed and the bottom plug in at low for 2.5 hours. Med for 2.5 hours. High until the kiln sitter trips. (on bisque I don't normally try a hold, but I make sure I've proceeded slowly through the temperatures to allow time for the organics to burn out and chemical changes to happen) Both of mine have a setting above high labeled "High fire" that I only use for glaze firing to cone 6. Yours looks to have a numbered scale which I don't have experience with but I would imagine it is similar with the highest setting being the maximum cone temp of the kiln. I normally set a timer on my phone to remind me to turn up the kiln and make sure the sitter has turned it back off. Link to comment Share on other sites More sharing options...
Marcia Selsor Posted January 8, 2015 Report Share Posted January 8, 2015 I don't see the need to hold the temperature for a bisque.I hold the temp. for evening out glazes. No problem mixing clay bodies in a bisque. Some people recommend 04 bisque for porcelain , but you aren't firing that. All of the above advice is good. Don't leave the kiln unattended. You can work in your studio, etc. but keep a steady eye on it. Marcia Link to comment Share on other sites More sharing options...
Mark C. Posted January 8, 2015 Report Share Posted January 8, 2015 Your kion has a cone sitter and a safety shut off timer. Put a small cone (whatever you want bisque to go to)say 06 and set timer for 10 hours-turn on kiln on that dial to about 1/3 let sit on that 2 hours-turn up to 1/2 on dial let sit another two hours-after that turn on full (close lid after a few hours) and watch for cone sitter to shut it off. Mix whatever clay bodies you want in bisques. Save some $$ for a digital pyrometer. Mark Link to comment Share on other sites More sharing options...
Limagirl Posted January 9, 2015 Author Report Share Posted January 9, 2015 Thank you everyone for the comments. I will watch the kiln, I am a bit overly thoroughly and would never leave my kiln unattended. I know a OSHA person who came out and helped me set up my studio to assure my hazards are low, maybe a little overkill but better safe than sorry. I will purchase a pyrometer. My pots have been drying for sometime, some 4 weeks, I have probably 3 bisque loads ready now. I will ask my instructor I have been working under to come and help with my first bisque. Much thanks to all of you! I have learned many things by watching all the forums, and will continue to learn. Link to comment Share on other sites More sharing options...
Limagirl Posted January 9, 2015 Author Report Share Posted January 9, 2015 Mark C., I bought the bars for the kiln sitter, I was told at the pottery shop not to use cones in the kiln sitter. I learned to use cones, so this really threw me. Are the bars ok? Link to comment Share on other sites More sharing options...
Benzine Posted January 9, 2015 Report Share Posted January 9, 2015 There is nothing wrong, with using cones in the sitter. I've fired this way numerous times, as have many other potters. With that said, there can be occasions, where the cone doesn't melt in a way, that allows for the sitter to trip off. I've never had it happen, but the kilns I used, always had a back up timer, that I set too. So as long as you are watching the kiln yourself, it's not an issue. There's a certain amount of time it will take, if the sitter doesn't do it's job, then you can shut it off. You should never depend on a mechanical device (sitter, digital controller) anyway. The only thing that is guaranteed not to fail, is you. Link to comment Share on other sites More sharing options...
Mark C. Posted January 9, 2015 Report Share Posted January 9, 2015 Bars are fine-they are made for kiln setters. You can put a dap of kiln wash on the edge of the metal prongs where the bar /cone rests as well. Mark Link to comment Share on other sites More sharing options...
Crusty Posted January 9, 2015 Report Share Posted January 9, 2015 i like the bars better, easier to set and fire more consistant because of their straight shape.. when i use the cones i always look at my trip set and make sure its set at the correct measurement .l have put them in before and overfired because i put the cone in to deep ... good luck to ya... Link to comment Share on other sites More sharing options...
oldlady Posted January 9, 2015 Report Share Posted January 9, 2015 limagirl, good luck with your firing. minibars are made to work in your kiln sitter. they are the same material as a regular cone but made to the correct volume of material to allow the bar to fall at the optimal time. there are no thin tops and thick bottoms to make you worry that you have put the thicker part where the bar will fall and will overfire and everything will be ruined!!!!!!!! sorry about the drama, i know how scary the first firing is. relax, the worst that can happen is................................(whatever you imagine will probably not happen.) read Pugaboos first firing posts. she lived through it and has thrived. Link to comment Share on other sites More sharing options...
PSC Posted January 9, 2015 Report Share Posted January 9, 2015 I've used bars and small cone no problem, actually i like the cone cause if i have particularly thick ware i push the cone a little to the thicker side for a little longer fire. I bisque to 04: 2 hours on low lid up 2 hours on low lid down 2 hours on medium And then turn to high and let the kiln turn itself off A lite load will fire faster and a crowded load will fire slower, i don't see why you would need to put a hold on the kiln for a bisque, holds are more for glaze development. Link to comment Share on other sites More sharing options...
bciskepottery Posted January 9, 2015 Report Share Posted January 9, 2015 You might consider a hold on bisque if you have high iron clay bodies, or clay bodies with manganese dioxide (Standard 266, etc), where you need to really make sure you burn out sulfur and other volatiles that could cause outgassing and problems (pinholing, for example) during the glaze firing. It all depends on your clay bodies. Link to comment Share on other sites More sharing options...
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