clay lover Posted March 27, 2015 Report Share Posted March 27, 2015 I have been trying to find a shorter bisque firing schedule, currently I take 16 hours with bone dry ware. The following has been recommended to me. Do you think it is safe? or too fast? Ramp 1 150* per hour to 200 hold 2 hours Ramp 2 200* per hour to 700* hold ?? Ramp 3 100* per hour to 1,000*, no hold Ramp 4 300* hour to 1925* hold 30 minutes This is a 13 hour total. Some of this was from a more experienced potter, with guidance from Hamer and Hamer's book. Link to comment Share on other sites More sharing options...
bciskepottery Posted March 27, 2015 Report Share Posted March 27, 2015 I use the pre-programmed Cone 05 slow bisque program in my L&L kiln: 80 degrees/hour to 250 degrees 200 degrees/hour to 1000 degrees 100 degrees/hour to 1100 degrees 180 degrees/hour to 1641 degrees 80 degrees/hour to 1891 degrees; hold for 5 minutes Firing time is just under 14 hours. Kiln vent is turned on at start; turned off when I unload. I only use a hold at 200 degrees if the wares are not dry. If you know your load is dry, there is not need for a hold at 200 degrees. When I fired kilns at a community studio, we did a preheat to 200 degrees because students put damp items on the bisque shelf and there was a variety of wall thicknesses in wares. At home, I seldom feel a need to preheat. Slowing down the rate of temperature rise at the end allows for the crud to burn out (same reason for slowing from 1000 to 1100 degrees). You can go faster climbs of temperature in-between, but a slow start to remove physical water, slow around 1000 to 1100 to remove chemical water, and slow at end to burn out crud seems to be key. Link to comment Share on other sites More sharing options...
Chris Campbell Posted March 27, 2015 Report Share Posted March 27, 2015 I have a programmed computer and my dry bisque firings run between 6-8 hours depending on whether I am doing a Cone 010 or 06. They call this their medium speed setting. 16 hours sounds too long for a load that is dry ... That is about the length of a Cone 6 firing for me. Link to comment Share on other sites More sharing options...
Min Posted March 27, 2015 Report Share Posted March 27, 2015 How thick are your pieces, sculpture or pots? Type of clay used, is it a cleaner firing porcelain or does it have lots of carbon bearing stuff to burn out? Do you run a vent, cram your bisque or is it loosely loaded? Like everything with clay I don't think there is one correct answer, it depends... If you have problems with pinholes in your glazed wares this has a strong possibility of being caused by either bisquing to fast or not enough venting with the bisque. Pots might not blow up in a fast bisque but carbon needs to burn out. Link to comment Share on other sites More sharing options...
David Woodin Posted March 27, 2015 Report Share Posted March 27, 2015 I have been trying to find a shorter bisque firing schedule, currently I take 16 hours with bone dry ware. The following has been recommended to me. Do you think it is safe? or too fast? Ramp 1 150* per hour to 200 hold 2 hours Ramp 2 200* per hour to 700* hold ?? Ramp 3 100* per hour to 1,000*, no hold Ramp 4 300* hour to 1925* hold 30 minutes This is a 13 hour total. Some of this was from a more experienced potter, with guidance from Hamer and Hamer's book. Assuming that you are firing thrown ware, for me this program is too slow. If I fire bisque with the bisque program, I use fast bisque no hold. If I fire with my own program , it is ramp @ 200 to 200 hold 30 minutes, ramp 300 to 1000 hold 5, ramp 250 to 1200 hold 10. step to 1680 hold 5, ramp 80 to 1830 hold 10, off. I bisque at 06. If I think things are not bone dry I use the preheat and hold10 to 30 minutes. David Link to comment Share on other sites More sharing options...
clay lover Posted March 27, 2015 Author Report Share Posted March 27, 2015 Clay is a mixture of 3 different types of stoneware. combination of thrown and hand built, not thick or heavy, no student work in this load. I don't have any problems with the schedule I am using, no pinholes or glaze dipping problems . I pack the bisque pretty tight, but only stack bowls and such 3 deep. I'm afraid of cracking the ones on the bottom of a deeper stack. The program I use was giving to me by a really cautious teacher and it work for me, but I am wondering if it is all necessary. Link to comment Share on other sites More sharing options...
High Bridge Pottery Posted March 27, 2015 Report Share Posted March 27, 2015 I go 100degC an hour (212degF an hour) for 9 hours. For things needing a little more care I add an extra hour into the first 100degC in temp rise. Link to comment Share on other sites More sharing options...
Babs Posted March 27, 2015 Report Share Posted March 27, 2015 100 an hour to 280, 150 to 600 , 200 to 700 , hold for 20 mins, then on full to end of bisque, temp in centigrade. Manual controls. Hold at 700 to get rid of h2o and burn out crud as stated above. Link to comment Share on other sites More sharing options...
Min Posted March 27, 2015 Report Share Posted March 27, 2015 I think Skutt's med schedule is: 1 200 ºF/HR 250 ºF 0 2 400 ºF/HR 1000 ºF 0 3 180 ºF/HR 1150 ºF 0 4 300 ºF/HR 1694 ºF 0 5 120 ºF/HR 1946 ºF 00.05 I would gradually make changes to your schedule to speed it up and see how it goes. Link to comment Share on other sites More sharing options...
PSC Posted March 30, 2015 Report Share Posted March 30, 2015 I'm using a non computer kiln my bisque runs 11 hours, 12 if it is a tight pack. Work is thrown and handbuilt, nothing overly thick and everything has to pass the cheek test before it goes in so no wet ware. Not sure if this helps with your computer firing. Link to comment Share on other sites More sharing options...
neilestrick Posted March 31, 2015 Report Share Posted March 31, 2015 I recommend to my customers that they bisque fire using the 'Fast Bisque' setting on an L&L, 'Medium' on other brands. It works fine for most pieces. If you're firing large or thick pieces, then use the 'Slow' setting. I often bisque fire on the 'Fast Glaze' setting, which takes just under 5 hours, and I've never had problems. I don't generally recommend bisque firing that fast, though. Link to comment Share on other sites More sharing options...
curt Posted April 3, 2015 Report Share Posted April 3, 2015 I normally have a long cautious water-smoking period at the beginning of my bisque. However these posts make me wonder how long does it actually take to steam all the water out of the pores of an average pot? How long does that water smoking period really have to be? I know a lot of the answer must be "it depends" but would be interested if anyone has a more definitive answer assuming "all else equal" Link to comment Share on other sites More sharing options...
neilestrick Posted April 3, 2015 Report Share Posted April 3, 2015 If the pot is dry, there's no need to do any preheat. There's also no need to do any holds during any of the ramps. I would slow down the last couple hundred degrees to 180 per hour or less, though, to make sure everything is getting burned out well. Link to comment Share on other sites More sharing options...
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