laurab Posted October 2, 2018 Report Share Posted October 2, 2018 Hi all, I just did my first bisque firing (cone 04). Loaded my kiln - witness cones on all shelves (03-04-05), and 2 hour ramps Low -Med 2 hrs Med to High. Kiln sitter (cone 04) kicked off at 1970 degrees after 8 hours. When I opened the kiln none of the witness cones are bent (melted) and it seems the bisque ware is not fully fired. (color isn't really white) using white stoneware. (Standard 240 with grog). Very disappointed for my first kiln firing. Did I loose this whole load or do I re fire? I am glaze firing to cone 6. (Well thats the intention). Any help would be greatly appreciated. thanks Laura Link to comment Share on other sites More sharing options...
Pres Posted October 2, 2018 Report Share Posted October 2, 2018 You have not lost a load, you can refire as much as needed to meet bisque temp. Set a witness-target cone where you can see it through a peep, and refire. Run your program, and if it shuts down, add more time. Keep a close watch on the cone. best, Pres Link to comment Share on other sites More sharing options...
Min Posted October 2, 2018 Report Share Posted October 2, 2018 1 hour ago, laurab said: kicked off at 1970 degrees after 8 hours How did you determine the temperature? For self supporting cones like you used and looking at an Orton cone chart for fast firing 1970 should have taken you to cone 04. Does your kiln have a timer with the kiln sitter that was set to 8 hours? What does the cone in the sitter look like? Is it bent? Link to comment Share on other sites More sharing options...
laurab Posted October 2, 2018 Author Report Share Posted October 2, 2018 The temperature was read with a pyrometer. The kiln sitter cone which was an 04 cone bent and kicked off the kiln at 7 1/2 hours. I have a timer on my kiln (its manual) and I set it to 8 hours. Link to comment Share on other sites More sharing options...
laurab Posted October 2, 2018 Author Report Share Posted October 2, 2018 2 minutes ago, Min said: How did you determine the temperature? For self supporting cones like you used and looking at an Orton cone chart for fast firing 1970 should have taken you to cone 04. Does your kiln have a timer with the kiln sitter that was set to 8 hours? What does the cone in the sitter look like? Is it bent? The temperature was read with a pyrometer. The kiln sitter cone which was an 04 cone bent and kicked off the kiln at 7 1/2 hours. I have a timer on my kiln (its manual) and I set it to 8 hours. Link to comment Share on other sites More sharing options...
laurab Posted October 2, 2018 Author Report Share Posted October 2, 2018 does it matter where you read the temperature with the pyrometer? Mine is in a hole at the top of the kiln Link to comment Share on other sites More sharing options...
Min Posted October 2, 2018 Report Share Posted October 2, 2018 Did you by any chance have cones on the shelf that below the sitter and if you did how do they look? Large manual kilns can fire unevenly. I would go by the cones more than the pyrometer, the cones show heat work, the pyrometer just shows temperature. I would check the calibration on your sitter before your next firing. How to do that here, it doesn't take long and it's fairly simple to do. For electronic kilns with only 1 thermocouple it's placed at about the middle of the kiln. Link to comment Share on other sites More sharing options...
laurab Posted October 2, 2018 Author Report Share Posted October 2, 2018 18 minutes ago, Min said: Did you by any chance have cones on the shelf that below the sitter and if you did how do they look? Large manual kilns can fire unevenly. I would go by the cones more than the pyrometer, the cones show heat work, the pyrometer just shows temperature. I would check the calibration on your sitter before your next firing. How to do that here, it doesn't take long and it's fairly simple to do. For electronic kilns with only 1 thermocouple it's placed at about the middle of the kiln. none of the witness cones bent. I thought I calibrated the kiln sitter, but will check again. thanks Link to comment Share on other sites More sharing options...
Min Posted October 3, 2018 Report Share Posted October 3, 2018 If you've already checked the calibration of the sitter then also check the rod and cone supports for deterioration. Link to comment Share on other sites More sharing options...
Babs Posted October 3, 2018 Report Share Posted October 3, 2018 Do your witness cones have 0 in front of numbers? Have you fired this clay before. Why do you think the ware Is underfired? Check the boxes to affirm that they are indeed 04 etc. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.