KayleighpP Posted June 22, 2023 Report Share Posted June 22, 2023 I’m currently working on a project where we are making vases in Earthenware, (CWE from Valentines Clays), using coloured slip made from the clay body, and a commercial transparent glaze. Then we are using quite a few different enamel transfers from different companies layered up. Now we’ve had the first vases out the kiln and one has significant pin holes/(spit out?) all over it inside and out, the other two have slightly less but do have it on them. Does anyone have experience of this and know how to solve it? Quote Link to comment Share on other sites More sharing options...
Min Posted June 22, 2023 Report Share Posted June 22, 2023 Hi Kayleigh and welcome to the forum! Could you post a picture of the pinholes/faults and also a link to the type of enamel transfers you are using? Quote Link to comment Share on other sites More sharing options...
KayleighpP Posted June 23, 2023 Author Report Share Posted June 23, 2023 Hi Min There are various decals from Bailey's Decals and Heraldic (possibly other companies), these are from the other artist's collection she doesn't have much information on them which is overly unhelpful, and has had them for some time. I have been able to successfully fire them on to ready-made china, however once onto vases made by me I am having this pin holing issue. Due to the nature of the design they are complex, however the other artist I'm collaborating with has had success with this method with a previous ceramicist, but I unfortunately can't get the information from that ceramicist. I am just in the dark on how they've managed to achieve it. I've attached a photo of the inside of the worse one and a close up of the outside as it's hard to see in a zoomed out photo. It has a raised gritty affect but if rubbed with wet and dry you can see the holes. Hope that all makes sense. Quote Link to comment Share on other sites More sharing options...
Hulk Posted June 23, 2023 Report Share Posted June 23, 2023 (edited) Looks like small raised bumps/blips/blisters, also small open holes? My guess would be overfired* and naught to do with the transfers, as there appears to be same faults throughout. What cone was the ware fired to? Valentine indicates firing range 1080ºC – 1160ºC, hence, about Cone 04 to Cone 1 Had you fired this clay before, with different results? Were the faults about the same throughout the kiln? Were there less faults on cooler levels (if any, typically the bottom shelf)? Any special procedure for this/these firing(s)? Valentine indicates that's a new clay. I'm not finding any critical reviews ...you might reach out to Valentine? It appears they are responsive to inquiry. If you do, please post an update? *and/or rapidly cooled after reaching peak temperature. Edited June 23, 2023 by Hulk italics Quote Link to comment Share on other sites More sharing options...
KayleighpP Posted June 23, 2023 Author Report Share Posted June 23, 2023 I have since found out that the transfers should be fired to 780°C for Earthenware, these were originally fired to 820°C, 180°C degrees ramp per hour as suggested by the Bailey's Decals company. However, on further research that firing program is suitable for China not Earthenware. I am hopeful that an adjustment in the firing program will resolve this issue. The bisque firing was 1120°C, and glaze 1100°C. There were three vases in the kiln and the one in the photo was most affected, the other two had a smaller amount only on the outside of them. They were side by side on the same shelf. Kiln was cleaned thoroughly before firing so not debris as far as I can see, as definitely looks like little blister/ pinholes. Quote Link to comment Share on other sites More sharing options...
Min Posted June 23, 2023 Report Share Posted June 23, 2023 (edited) Top firing temp can vary between decal manufacture's. If the glaze is starting to soften/melt at the decal firing temp this could be the problem. Also, did you leave the pots to dry for 24 hours before firing the decals? this wouldn't have caused the glaze to blister though. Edited June 23, 2023 by Min Quote Link to comment Share on other sites More sharing options...
KayleighpP Posted June 23, 2023 Author Report Share Posted June 23, 2023 Yes they were left for several weeks as this is done by an artist and they get them delivered to my studio for firing. Quote Link to comment Share on other sites More sharing options...
Rae Reich Posted June 24, 2023 Report Share Posted June 24, 2023 If these bumps didn’t appear until the decal firing, I think maybe that could be because of incomplete/inefficient earlier firings. I would definitely show your results to the clay maker, especially since it’s a new formula. Quote Link to comment Share on other sites More sharing options...
Babs Posted June 24, 2023 Report Share Posted June 24, 2023 On 6/24/2023 at 3:58 AM, KayleighpP said: I have since found out that the transfers should be fired to 780°C for Earthenware, these were originally fired to 820°C, 180°C degrees ramp per hour as suggested by the Bailey's Decals company. However, on further research that firing program is suitable for China not Earthenware. On 6/24/2023 at 3:58 AM, KayleighpP said: I have since found out that the transfers should be fired to 780°C for Earthenware, these were originally fired to 820°C, 180°C degrees ramp per hour as suggested by the Bailey's Decals company. However, on further research that firing program is suitable for China not Earthenware. I am hopeful that an adjustment in the firing program will resolve this issue. The bisque firing was 1120°C, and glaze 1100°C. There were three vases in the kiln and the one in the photo was most affected, the other two had a smaller amount only on the outside of them. They were side by side on the same shelf. Kiln was cleaned thoroughly before firing so not debris as far as I can see, as definitely looks like little blister/ pinholes. I can hardly believe the bisque temp. 1120°C that's what? Cone 01ish, did you mean 1020? NIthing to do with your query but seems very high. Quote Link to comment Share on other sites More sharing options...
KayleighpP Posted June 25, 2023 Author Report Share Posted June 25, 2023 No I did mean 1120°c - when I was taught ceramics at University it was always to high bisque Earthenware and low bisque Stoneware. Quote Link to comment Share on other sites More sharing options...
Rae Reich Posted June 25, 2023 Report Share Posted June 25, 2023 (edited) 10 hours ago, KayleighpP said: No I did mean 1120°c - when I was taught ceramics at University it was always to high bisque Earthenware and low bisque Stoneware. If you are brushing on glaze, a high bisque for earthenware makes sense. It wouldn’t suck up the moisture in the glaze as fast. Would be worse for dipping, I think. Edited June 25, 2023 by Rae Reich Quote Link to comment Share on other sites More sharing options...
Callie Beller Diesel Posted June 26, 2023 Report Share Posted June 26, 2023 A high bisque/lower glaze is a cycle that’s designed to eliminate a lot of clay-based flaws in glazes, so I don’t think it’s your chosen firing cycles. I agree with Min that your glaze is likely beginning to re-melt in the decal firing, especially since the glaze is mature at 1100 C. I think you’re on the right track in trying the lower decal firing temperature first. If that doesn’t work, you may need to change your clear/base glaze. Rae Reich 1 Quote Link to comment Share on other sites More sharing options...
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