MarkS Posted April 26, 2011 Report Share Posted April 26, 2011 Just took another load out of the kiln and have a question. I used a ^6 cone(bar) in the kiln sitter which shut off after about 10 1/2 hours. I had placed small ^6 cones on each of the three shelves (stuck in a wad of clay) - however none of these cones was in the least bit bent. I am not sure if i should go up to a ^7 in the sitter or just manually fire it a bit longer till I see the other cones bend. Does the weight of the rod in the kiln sitter make it bend faster than it would by itself? I don't want to second guess cause I'm usually wrong. Link to comment Share on other sites More sharing options...
Chris Campbell Posted April 26, 2011 Report Share Posted April 26, 2011 I usually use three groups of larger 'witness' cones inside the kiln. If I were firing to cone 6, I would have a 5, 6 and 7 on each level. That way you can get a better idea of just how much longer you need to fire. My small kiln fires about one cone lower so I use a cone 7 bar when I want cone 6. Link to comment Share on other sites More sharing options...
MarkS Posted April 26, 2011 Author Report Share Posted April 26, 2011 Looks like I may have to invest in some more cone and some cone stands if I really want to understand this. Link to comment Share on other sites More sharing options...
Denice Posted April 26, 2011 Report Share Posted April 26, 2011 Looks like I may have to invest in some more cone and some cone stands if I really want to understand this. Mark from what I have been told is that the small cone bending is designed with the pressure bars on it, so without the pressure it will bend later. I have tested my kiln setter using the large cones one higher and one lower than my desired cone that's in the middle with the small cone in the setter. I just use a rectangle of clay to set the large cones in at a slight angle so they will melt and fall in one direction. Denice (Wichita, KS) Link to comment Share on other sites More sharing options...
Lucille Oka Posted April 26, 2011 Report Share Posted April 26, 2011 Just took another load out of the kiln and have a question. I used a ^6 cone(bar) in the kiln sitter which shut off after about 10 1/2 hours. I had placed small ^6 cones on each of the three shelves (stuck in a wad of clay) - however none of these cones was in the least bit bent. I am not sure if i should go up to a ^7 in the sitter or just manually fire it a bit longer till I see the other cones bend. Does the weight of the rod in the kiln sitter make it bend faster than it would by itself? I don't want to second guess cause I'm usually wrong. Check the temperatures and rates of your cones and bars. Cone 6 in a bar, cone 6 in a small cone, cone 6 in a large cone and cone 6 in self supporting cones have different temperatures and firing rates. Link to comment Share on other sites More sharing options...
MarkS Posted April 26, 2011 Author Report Share Posted April 26, 2011 According to the Orton website the small cones and bars are made from the same material and therefore equivalent. Link to comment Share on other sites More sharing options...
Marcia Selsor Posted April 26, 2011 Report Share Posted April 26, 2011 You should make sure the setter is properly calibrated. You can get the calibration disc that slides over the rod and the support arms for the cone. Often the weight can slip over time and needs to be reset. You just need a small screwdriver to loosen the set screw on the weight and reset the weight's position. Marcia Link to comment Share on other sites More sharing options...
GEP Posted April 27, 2011 Report Share Posted April 27, 2011 According to the Orton website the small cones and bars are made from the same material and therefore equivalent. I believe the small cones and the bars are designed to behave the same when they're used in a kiln sitter. The small cones won't bend like a witness cone when they are just standing by themselves. Like you mentioned earlier, it takes the weight of the kiln sitter rod to make them bend. I second Chris's recommendation ... buy a range of large witness cones (5,6,7) and find out exactly what cone you're hitting. Then you can adjust your kiln sitter, either by calibrating the kiln sitter or using a different cone, to get your kiln to the temperature you want. Mea Link to comment Share on other sites More sharing options...
Marcia Selsor Posted April 27, 2011 Report Share Posted April 27, 2011 I agree with Mea and Chris. Large cones are also much easier to see inside the peep holes. I always fire electrics with witness cones..especially the digitally controlled kilns where the temperature readings don't seem to match the cones. Marcia Link to comment Share on other sites More sharing options...
MarkS Posted April 27, 2011 Author Report Share Posted April 27, 2011 I did find the gauge to calibrate the kiln sitter and all seems in order there. So off to buy some cones! Thanks for all the help. Link to comment Share on other sites More sharing options...
clayshapes Posted April 27, 2011 Report Share Posted April 27, 2011 Just FYI -- I've had the same issue -- I re calibrated the kilnsitter and started using one cone hotter in the sitter, as many recommend. It still bends before the larger witness cone on the bottom shelf, but only by about a half hour. So when it turns my (old Duncan) kiln off, I set it to manual and set my timer to check every 15 minutes to watch the witness cone progress through the peephole -- it usually take another half hour - sometimes an hour. It's a bit tedious, but I end up with good results. By the way -- I never use three witness cones. Takes up too much valuable space in my small kiln -- and I can rely on the large witness cone if I check regularly near the end. But that's just me, and my kiln. I'm sure others will think this is unwise, but it's worked for me...now that my kiln and I have gotten to know each other better! Link to comment Share on other sites More sharing options...
minspargal Posted April 28, 2011 Report Share Posted April 28, 2011 You got some good advice about using 3 large cones and calibrating. You might also check your cone sitter holders. Some times they get rough and stick to the sitter cone causing an overfire. I clean them with some sandpaper every now and then. Link to comment Share on other sites More sharing options...
MarkS Posted April 28, 2011 Author Report Share Posted April 28, 2011 So, can the small cones not be used as witness cones? Link to comment Share on other sites More sharing options...
GEP Posted April 28, 2011 Report Share Posted April 28, 2011 <br>So, can the small cones not be used as witness cones?<br><br><br>I've read conflicting advice about this, some people think it's ok to use them as witness cones. But I've also read that they are adjusted to bend with the weight of the kiln sitter rod, and also to soften at a higher temp, because kiln sitters are against the wall of the kiln which is hotter than the rest of the kiln. Personally, I think it is really hard to set them at the right angle because they are so small. Much easier to get that right with a full-size cone. Mea Link to comment Share on other sites More sharing options...
Marcia Selsor Posted April 29, 2011 Report Share Posted April 29, 2011 You got some good advice about using 3 large cones and calibrating. You might also check your cone sitter holders. Some times they get rough and stick to the sitter cone causing an overfire. I clean them with some sandpaper every now and then. I always keep a coat of kiln wash on the sitter holders and the rod. I think this is good maintenance. Marcia Link to comment Share on other sites More sharing options...
Lucille Oka Posted April 29, 2011 Report Share Posted April 29, 2011 Just took another load out of the kiln and have a question. I used a ^6 cone(bar) in the kiln sitter which shut off after about 10 1/2 hours. I had placed small ^6 cones on each of the three shelves (stuck in a wad of clay) - however none of these cones was in the least bit bent. I am not sure if i should go up to a ^7 in the sitter or just manually fire it a bit longer till I see the other cones bend. Does the weight of the rod in the kiln sitter make it bend faster than it would by itself? I don't want to second guess cause I'm usually wrong. By the way, how did the ware turn out?? Link to comment Share on other sites More sharing options...
ClayHouse Studio Posted April 29, 2011 Report Share Posted April 29, 2011 I agree with Marcia to calibrate the kiln sitter, however regardless of setter for auto shut off of the kiln, it should always be fired by a witness cone set. make sure the setter pyrometric bar is a proper ^ temp, you find using a standard pyrometric cone in place of the pyrometric bar will do the trick and place it on the setter with point of triangle down on posts and flat edge to the setter shut off bar. Check for even heat in the kiln, sometimes ware and shelves too close to the setter cone will cause the setter cone to bend quicker. Then check your heating elements, 10 1/2 hours should be plenty of time to bend a witness cone 6. Link to comment Share on other sites More sharing options...
Denice Posted May 2, 2011 Report Share Posted May 2, 2011 I agree with Marcia to calibrate the kiln sitter, however regardless of setter for auto shut off of the kiln, it should always be fired by a witness cone set. make sure the setter pyrometric bar is a proper ^ temp, you find using a standard pyrometric cone in place of the pyrometric bar will do the trick and place it on the setter with point of triangle down on posts and flat edge to the setter shut off bar. Check for even heat in the kiln, sometimes ware and shelves too close to the setter cone will cause the setter cone to bend quicker. Then check your heating elements, 10 1/2 hours should be plenty of time to bend a witness cone 6. Hey Marc, Ortonceramics.com has a lot of information available maybe if you checked it out you can get all of this helpful information to make sense, it sounded like you were getting frustrated and confused. Denice Link to comment Share on other sites More sharing options...
MarkS Posted May 3, 2011 Author Report Share Posted May 3, 2011 I will say most everything else turned out fine and I had a mix of different shapes, sizes, and glazes. Maybe the Temmoku glaze isn't meant to be real glossy? I thought I read somewhere to put the base (flat part)of the cone on the cone sitter posts but I'm not sure. I use the bars. Link to comment Share on other sites More sharing options...
Arnold Howard Posted May 3, 2011 Report Share Posted May 3, 2011 I thought I read somewhere to put the base (flat part)of the cone on the cone sitter posts but I'm not sure. I use the bars. Yes, the flat side of the cone goes down, toward the cone supports, in the Kiln Sitter. This is because that side is less likely to tear than an edged side as the cone bends. Most people use a hotter cone in the Kiln Sitter than on the shelf. The cone that most accurately measures the heat work is the witness cone on the shelf. Sincerely, Arnold Howard Paragon Industries, L.P., Mesquite, Texas USA ahoward@paragonweb.com / www.paragonweb.com Link to comment Share on other sites More sharing options...
Lucille Oka Posted May 4, 2011 Report Share Posted May 4, 2011 I thought I read somewhere to put the base (flat part)of the cone on the cone sitter posts but I'm not sure. I use the bars. Yes, the flat side of the cone goes down, toward the cone supports, in the Kiln Sitter. This is because that side is less likely to tear than an edged side as the cone bends. Most people use a hotter cone in the Kiln Sitter than on the shelf. The cone that most accurately measures the heat work is the witness cone on the shelf. Sincerely, Arnold Howard Paragon Industries, L.P., Mesquite, Texas USA ahoward@paragonweb.com / www.paragonweb.com To Arnold: Our friend Mark S is having a problem with using the small witness cones on the shelf. He says that they didn’t melt. Can you tell him and all of us the reasons why small cones or any cone for that matter can 'freeze' and not melt? We know that there could be variations of temperature in his kiln or placement of cones near an open peep hole. But what else can cause these problems. Thanks in advance. And remember Mark S., having a successful firing is not whether the cones melted but how the glazes turned out. If the glazes or ware are defective in some way then that is when we usually start searching for causes for what went wrong. And Orton says that you can use the smaller cone if 15/16ths†is sticking out from the clay pad and if the cone is placed at an 8 degree angle. Wow tough huh? How do you feel about wall mounted pyrometers? Link to comment Share on other sites More sharing options...
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