morepots Posted August 22 Report Share Posted August 22 (edited) Has anyone had success with porcelain or alternative to porcelain (say bone china) producing large (14") very thin (1/8") pieces without warpage? It's an upside down bowl shape. Obviously a very specific technical question here I'm fumbling with. It's for a very large pendant lamp that needs to be translucent. Tried firing porcelain with chuck inside and out. Severe warpage. Tried molochite -- still too thin to fire without warpage, also translucency is compromised. Looking to the community for words of experience. Thank you Edited August 22 by moh Quote Link to comment Share on other sites More sharing options...
PeterH Posted August 23 Report Share Posted August 23 Two pretty obvious points. 1) Bone china warps more than porcelain (hence the high-bisque low glost). So it's not an answer to warping problems. Can be nice stuff though. 2) You may just have to support your form better. Which might also involve a switch to high-bisque low glost. 3) Are you using a setter? Might one help? A picture of you "lampshade" and its firing supports might help the experts. PS A thread on somebody trying to fire an inherently unstable form. Hulk 1 Quote Link to comment Share on other sites More sharing options...
Jeff Longtin Posted August 23 Report Share Posted August 23 Yes, I have had success firing large porcelain forms without warpage. For your problem, however, I will direct you to a glass slumping supply catalog. (Looks like a site called slumpys.com is a good place to start.) What you will see are forms that are fully supported at the rim so the chuck/setter form has no way of warping. You will need to make a similar shape for your setter. Different from glass setters you will need to make a setter from scratch and fire it with your porcelain form so it shrinks at the same rate. Good Luck PeterH and Hulk 2 Quote Link to comment Share on other sites More sharing options...
PeterH Posted August 24 Report Share Posted August 24 (edited) 23 hours ago, Jeff Longtin said: Different from glass setters you will need to make a setter from scratch and fire it with your porcelain form so it shrinks at the same rate. Making a "bespoke" setter for a cast shape. A picture of you "lampshade" and its firing supports From https://tinyurl.com/mryx92z7 A picture of you "lampshade" and its firing supports would help. Edited August 24 by PeterH Hulk 1 Quote Link to comment Share on other sites More sharing options...
PeterH Posted August 25 Report Share Posted August 25 (edited) >Obviously a very specific technical question here I'm fumbling with. It's for a very large pendant lamp that needs >to be translucent. >Tried firing porcelain with chuck inside and out. Severe warpage. >Tried molochite -- still too thin to fire without warpage, also translucency is compromised. Pictures? All porcelains are not equal, a couple of "background" references. Warping https://digitalfire.com/trouble/warping ... including suggestions to address Edited August 25 by PeterH Hulk 1 Quote Link to comment Share on other sites More sharing options...
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