Io Palmer Posted July 7 Report Share Posted July 7 Hello ceramic community. I am hoping someone out there can help me figure out this problem. I use a white midrange clay to build tableware from rolled slabs. I apply a well known slip recipe I have used for years , underglazes and a midrange clear glaze. After the work is glaze fired , I noticed that at least half of the pieces ( cups ) chip off where the thicker application of slip is. The odd thing is that I have been using the same slip and clay for years w no real problems. The chipped off slip and glaze will sometimes take two to three days to chip off. hoping someone can help me out. I am so sad and feel like I dont know how to fix this problem. many thanks for your time. Io Palmer Quote Link to comment Share on other sites More sharing options...
Babs Posted July 8 Report Share Posted July 8 If the chips are occurring on the rims I would think the rims were drier when slip applied and so the slip bloats off at glaze firing. I suggest getting the cups onto rims as quick after after assembling, spritzing the whole cup with water esp rim prior to applying slip and drying uniformly. Quote Link to comment Share on other sites More sharing options...
Io Palmer Posted July 8 Author Report Share Posted July 8 Thanks Babs. The chipping is happening not on the rims. I am going to send photo. The chips occur where the slip is applied thicker ( stencils and slip trailing). I put the slip on when it is leather. These slips I am using were made for leather application. Quote Link to comment Share on other sites More sharing options...
Kelly in AK Posted July 8 Report Share Posted July 8 Well something has changed, we’ve got to figure out what. Is it possible the clay body formula has changed? In the recent past many clay companies have reformulated certain bodies due to material shortages (mostly talc, I understand). It may be worth asking your supplier if you’re not sure. Another thought is that maybe your slip has changed. I get the impression you mix it yourself, have you gotten any new batches of material? Perhaps one of those is different. Made any substitutions? I hate to say it, but since we’ve all done this, it could even be a measurement error when you were compounding the slip recipe. All is not lost. Something has to be adjusted. If you post the name of the clay body and slip recipe there’s a fair chance people here could help you sleuth that out. Quote Link to comment Share on other sites More sharing options...
Babs Posted July 8 Report Share Posted July 8 6 hours ago, Io Palmer said: Thanks Babs. The chipping is happening not on the rims. I am going to send photo. The chips occur where the slip Can you test if another coloyred slip does this when applied thickly? Do you need to apply it thickly? Quote Link to comment Share on other sites More sharing options...
Io Palmer Posted July 8 Author Report Share Posted July 8 Thanks Babs. The chipping is happening not on the rims. I am going to send photo. The chips occur where the slip is applied thicker ( stencils and slip trailing). I put the slip on when it is leather. These slips I am using were made for leather application. Quote Link to comment Share on other sites More sharing options...
Io Palmer Posted July 8 Author Report Share Posted July 8 7 hours ago, Babs said: Can you test if another coloyred slip does this when applied thickly? Do you need to apply it thickly? unfortunately it is happening to all of them Whichever color - they are all subject to this disease I like to do some slip trail - or dot trail as I call it - I don’t know how to get that effect otherwise . But I may have to alter my process The odd thing is I have used the same slips for over 1 year Meaning - the same batch and it used to work now it doesn’t There isn’t an expiration date on slips I don’t think thanks for your time Thanks Babs. The chipping is happening not on the rims. I am going to send photo. The chips occur where the slip is applied thicker ( stencils and slip trailing). I put the slip on when it is leather. These slips I am using were made for leather application. Quote Link to comment Share on other sites More sharing options...
Io Palmer Posted July 8 Author Report Share Posted July 8 8 hours ago, Kelly in AK said: Well something has changed, we’ve got to figure out what. Is it possible the clay body formula has changed? In the recent past many clay companies have reformulated certain bodies due to material shortages (mostly talc, I understand). It may be worth asking your supplier if you’re not sure. Another thought is that maybe your slip has changed. I get the impression you mix it yourself, have you gotten any new batches of material? Perhaps one of those is different. Made any substitutions? I hate to say it, but since we’ve all done this, it could even be a measurement error when you were compounding the slip recipe. All is not lost. Something has to be adjusted. If you post the name of the clay body and slip recipe there’s a fair chance people here could help you sleuth that out. thank you for your time Kay. this all makes sense what you are saying however - w the slips that I mix myself are the same slips I have used for a year - meaning the same exact batch from a year ago. I am a slow maker w the cups. So they used to work just fine. same w the clear glaze - same batch I mixed up a year ago. the midrange clay is called Georgie’s G Mix and the slip recipe is Eva Kwong Slip Recipe. the frustration is that the slips are the exact same. I wonder if it is the clay somehow. I don’t know that recipe but can call and see what is up. love the clay community. io Kelly in AK 1 Quote Link to comment Share on other sites More sharing options...
Io Palmer Posted July 8 Author Report Share Posted July 8 Sorry - Meant to say Kelly. Kelly in AK 1 Quote Link to comment Share on other sites More sharing options...
Min Posted July 8 Report Share Posted July 8 Is it a new batch of clay that the problems started with than when the slip didn't have this issue? I would suggest taking one of the slips and drying it out so it is at a clay like consistency and doing some laminated tests with it to see how it fits the clay. If you go to this link and scroll down to "Bi Clay Strips Compatibility" it shows how to run one of these tests. Quote Link to comment Share on other sites More sharing options...
PeterH Posted July 8 Report Share Posted July 8 45 minutes ago, Io Palmer said: the midrange clay is called Georgie’s G Mix and the slip recipe is Eva Kwong Slip Recipe. Is the clay G-Mix 6 https://www.georgies.com/gcc-clay-mid.shtml or G-Mix 10 https://www.georgies.com/gcc-clay-high.shtml Is this the slip? https://ceramicartsnetwork.org/ceramic-recipes/recipe/Kwong-Mangus-All-Purpose-Greenware-Slip-with-multiple-color-options-169109# ... can you confirm that you are still using the same bags you used previously Quote Link to comment Share on other sites More sharing options...
Io Palmer Posted July 8 Author Report Share Posted July 8 It is the cone 6 G mix. And yes that is the recipe I use for slip. I mixed up one big batch of powder slip then separate them out to then add the stain. I have used the same batches of slip for a while now. Just add a bit of water if it needs it. I have had the same batch in my studio for the last year or so. Quote Link to comment Share on other sites More sharing options...
Io Palmer Posted July 8 Author Report Share Posted July 8 1 hour ago, Min said: Is it a new batch of clay that the problems started with than when the slip didn't have this issue? I would suggest taking one of the slips and drying it out so it is at a clay like consistency and doing some laminated tests with it to see how it fits the clay. If you go to this link and scroll down to "Bi Clay Strips Compatibility" it shows how to run one of these tests. Thank you for this ! Quote Link to comment Share on other sites More sharing options...
Io Palmer Posted July 8 Author Report Share Posted July 8 And yes , it was a new batch of clay. Quote Link to comment Share on other sites More sharing options...
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