Shelly-jvp Posted January 17, 2021 Report Share Posted January 17, 2021 This is my first question on the forum and I hope I'm using the correct field to post it in. My friend in Germany is using BSZ Engobe((1020 c to 1180c) on top of Black Clay 25% grog . She applied to leather hard clay a base of white , waited 20 minutes and then applied a second layer of a different color. During the drying phase the engobe started to flake off. She also made another piece and did not use white as an undercoat but stuck to a solid coat (no second coat). There was no flaking during the drying phase. Does anyone have experience with engobe flaking during the drying phase? We are newbies to all of this and don't have a clue as to what is going on or how to fix the problem. Thank you in advance for your help! See image below Link to comment Share on other sites More sharing options...
Bill Kielb Posted January 17, 2021 Report Share Posted January 17, 2021 Since these were the same product, just different colors it would appear that as the second coat dried it pulled the first coat off due to shrinkage. She could try applying the second coat as soon as practical rather than waiting 20 minutes.. The problem with this is if shrinkage rates are significantly different than the body and the plasticity of the material applied or its ability to adhere to the body, it may be hard to get these to all stay together at the various stages they will need to go through. This can manifest itself more and more as the layer thickens. Testing is really the only way to find out. Not really something that can be calculated or predicted in my experience. Link to comment Share on other sites More sharing options...
Min Posted January 17, 2021 Report Share Posted January 17, 2021 Hi Shelly and welcome to the forum. Could you give a bit more info about the engobe your friend is using in Germany? It could be what we would call and underglaze in North America or it could be an engobe. There are different definitions of what an engobe is so if what the product actually is could be clarified first it would help. If indeed it is what we in North America call an underglaze the problem could be that it was applied too thick and needs thinning down with water. Link to comment Share on other sites More sharing options...
Sorcery Posted January 18, 2021 Report Share Posted January 18, 2021 Was it sgraffito'd too? The white was the same engobe? Why Engobe? I can't put slip(Engobe) over glaze or this happens. Sorce Link to comment Share on other sites More sharing options...
glazenerd Posted January 18, 2021 Report Share Posted January 18, 2021 A clay with 25% grog has a vastly different drying rate than a stoneware: or even porcelain. The porosity of a clay body is much higher: which means it will also wick moisture from anything put over it. An analogy would be a dry sponge wicking up water. ( extreme, but you get the picture) A body with 25% grog is primarily designed for sculptural or large format use. Link to comment Share on other sites More sharing options...
Shelly-jvp Posted January 20, 2021 Author Report Share Posted January 20, 2021 On 1/17/2021 at 11:04 AM, Bill Kielb said: On 1/17/2021 at 11:04 AM, Bill Kielb said: Thank you all for your help. Link to comment Share on other sites More sharing options...
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