Spiros Posted January 3, 2023 Report Share Posted January 3, 2023 Hello fellow potters!!! I have a quick question for you. Yesterday I made 2 female sculptures out of clay and the air was free from base to the head so no problem exploding. The second sculpture though at some point I had the head nearly cut off from the neck so I put it back together with slip and I used a bamboo skewer to hold it so it won't come off again. Now that is half dried, I cannot remove the skewer as it stuck to the neck of the sculpture.. my question is, if i put it in the kiln when it's all dried and ready to be fired, will the head explode because of the air trapped, or the skewer will burn out first so the air can escape from the neck down to the base? Thanks in advance!!! Quote Link to comment Share on other sites More sharing options...
Min Posted January 3, 2023 Report Share Posted January 3, 2023 Trapped air doesn't cause explosions. What causes explosions is moisture in the clay. It can take a long time for all the moisture to leave the clay so oftentimes people leave a vent hole, not for the moisture to escape but for the air circulation to allow moisture to facilitate moisture escape. Air trapped inside work can rarely cause clay cracking, but not exploding, as the air expands when heated. I would do whatever you need to do to get that wood skewer out of there. As the clay continues to shrink it can crack as the skewer won't shrink. Welcome to the forum Spiros, Chilly, Callie Beller Diesel and 1 other 4 Quote Link to comment Share on other sites More sharing options...
Spiros Posted January 3, 2023 Author Report Share Posted January 3, 2023 Thank you Min for accepting me !!! I always thought air trapped can cause explosion too.. so if you make a big sphere on the wheel without a hole, you let it dry and put it in the kiln, it wouldn't explode if all dried properly? Quote Link to comment Share on other sites More sharing options...
Min Posted January 3, 2023 Report Share Posted January 3, 2023 3 hours ago, Spiros said: so if you make a big sphere on the wheel without a hole, you let it dry and put it in the kiln, it wouldn't explode if all dried properly? Correct. Make sure it is bone dry when fired. Pres and Spiros 2 Quote Link to comment Share on other sites More sharing options...
Callie Beller Diesel Posted January 3, 2023 Report Share Posted January 3, 2023 If the piece is on the thick side and depending on the humidity in your area, you might want to add a soak hold to your bisque. Keep it around 80*C for a few hours at the start of the firing to ensure the piece is indeed bone dry. Pres, Spiros and Rae Reich 3 Quote Link to comment Share on other sites More sharing options...
PeterH Posted January 3, 2023 Report Share Posted January 3, 2023 If you heat air from 0°C to 1000°C it expands to less than five times its size. [It goes from 273°K to 1273°K and expands to 1273/273 its size.] Water expands by about 1700 times when it turns into steam (over a much shorter temperature range). at's a lot. Spiros, kswan, Rae Reich and 1 other 4 Quote Link to comment Share on other sites More sharing options...
Spiros Posted January 4, 2023 Author Report Share Posted January 4, 2023 Guys thank you very much for the information! Explosion due to air myth was busted... I will let my work dry very slowly and hopefully it won't break the neck as the skewer won't come off and i dont want to put more pressure to it. I will let it dry completely before firing as usual. To be honest I never had experienced an explosion probably because I leave my work dry for another couple of days from the time I'm sure its bone dry. Hopefully it will come out in one piece. I will let you guys know when its fired! Thanks for all the comments and your time!!! Quote Link to comment Share on other sites More sharing options...
Min Posted January 4, 2023 Report Share Posted January 4, 2023 Try putting the piece on your cheek then take another piece that you absolutely know for sure is dry and put it on the other cheek. If one feels cooler than the other it isn't dry enough to put in the kiln. As Callie said go slow with the firing, soak (aka candle) the kiln at about 90C/200F overnight to ensure it's dry all the way through. Spiros 1 Quote Link to comment Share on other sites More sharing options...
Denice Posted January 4, 2023 Report Share Posted January 4, 2023 Your skewer is going to cause your clay to crack, your clay continually shrinks as it dries your skewer doesn't unless is it is made of a flimsy material that is easy to crush. Denice Spiros 1 Quote Link to comment Share on other sites More sharing options...
Spiros Posted January 4, 2023 Author Report Share Posted January 4, 2023 I'm not too worried about the shrink cause a crack, because I didnt go through clay with the skewer. There was a hole at the neck that was a bit bigger than the skewer. I dont know why I used the the skewer, I just had it next to me and it was a fast solution to put the head back together. Normally I use nikrothal wire at different widths to keep joints together. I get cracks some times with thick wire when I go through clay with it. Hopefully this won't happen this time as there was a bigger hole there. I'll cross fingers and pray. It's a good trick load my works fire and stay at 100°C for a few hours to evaporate water. I do that when I want to make sure they are fully dried!!! Rae Reich, Hulk, Pres and 2 others 5 Quote Link to comment Share on other sites More sharing options...
Rae Reich Posted January 5, 2023 Report Share Posted January 5, 2023 Nice work! Spiros 1 Quote Link to comment Share on other sites More sharing options...
Spiros Posted January 5, 2023 Author Report Share Posted January 5, 2023 1 hour ago, Rae Reich said: Nice work! Thank you Rae, I will post a picture when glazed (hopefully with no crack) Rae Reich 1 Quote Link to comment Share on other sites More sharing options...
oldlady Posted January 5, 2023 Report Share Posted January 5, 2023 i applaud your skill in balancing such a large top on such a slender base. Spiros 1 Quote Link to comment Share on other sites More sharing options...
Spiros Posted January 5, 2023 Author Report Share Posted January 5, 2023 3 hours ago, oldlady said: i applaud your skill in balancing such a large top on such a slender base. Thank very much old lady! I wanted to emphasize what she wears on her head. Clay shows you where to bend or put weight so it won't fall and I make the bottom part just a little bit thicker than the top at her head. The other sculpture is similar with a large top but even taller. Roberta12 1 Quote Link to comment Share on other sites More sharing options...
Chilly Posted January 11, 2023 Report Share Posted January 11, 2023 On 1/4/2023 at 12:09 AM, Spiros said: skewer won't come off Can you burn it out? This will obviously happen in the kiln, but it might be worth experimenting with a lump of clay and another skewer beforehand to see if setting fire to the skewer will let it burn out and not crack the clay. Quote Link to comment Share on other sites More sharing options...
Spiros Posted January 12, 2023 Author Report Share Posted January 12, 2023 6 hours ago, Chilly said: Can you burn it out? This will obviously happen in the kiln, but it might be worth experimenting with a lump of clay and another skewer beforehand to see if setting fire to the skewer will let it burn out and not crack the clay. I dont think it would burn because of the lack of oxygen. I thought soaking the skewer with a flammable liquid like alcohol or petrol and then set it on fire but I didnt do it because even then it probably wouldn't burn where the clay was round the skewer.. well it's in the kiln cooling down at the moment. It's about 220°C so in about 8 hrs I'll know if cracked.. Chilly 1 Quote Link to comment Share on other sites More sharing options...
Spiros Posted January 12, 2023 Author Report Share Posted January 12, 2023 22 hours ago, Chilly said: Ok guys my pieces survived the kiln with no cracks and no exploding for sure!!! So happy I got them out safely!!! Glaze time now :) Roberta12, Hulk, Chilly and 3 others 6 Quote Link to comment Share on other sites More sharing options...
Mark C. Posted January 12, 2023 Report Share Posted January 12, 2023 (edited) Some basic rules apply here-wood will burn out at bisques temps. No matter what . Air ii clay does not explode its the moisture in the clay blowing up.from going up to fast in temp. The cure is to dry it more and fire it slower. That will always fixs blowing up and most cracking issues. glaze time sounds fun nice looking work Edited January 13, 2023 by Mark C. Spiros 1 Quote Link to comment Share on other sites More sharing options...
Min Posted January 13, 2023 Report Share Posted January 13, 2023 @Spiros, they look lovely just like they are! Are you concerned that the one on the left might tip during the glaze fire? Roberta12 1 Quote Link to comment Share on other sites More sharing options...
Spiros Posted January 15, 2023 Author Report Share Posted January 15, 2023 On 1/13/2023 at 2:42 AM, Min said: @Spiros, they look lovely just like they are! Are you concerned that the one on the left might tip during the glaze fire? I'm not concerned about that. They stand really well on their own. Actually when fired previously they were layed down. This time they stand as they are in the kiln because of glaze on their dresses. Quote Link to comment Share on other sites More sharing options...
Spiros Posted January 17, 2023 Author Report Share Posted January 17, 2023 Glaze firing was a success!!! I think I should make a few more like these and not concerned about any air trapped like everybody said! Thanks everyone for your time, tips and comments !!! Greetings from Greece !!! Callie Beller Diesel, Hulk, Kelly in AK and 2 others 5 Quote Link to comment Share on other sites More sharing options...
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