Judy SA Posted March 3, 2023 Report Share Posted March 3, 2023 I teach a ceramic class at The Salvation Army. I am using Standard low fire slip which I fire to cone 05. The bisque looks white. My problem is when I use a clear glaze and fire it to 05 or 06 it comes out looking yellowish or creamy. I am aware of the formula change. I have tried thinning it with distilled water, and putting on a thinner coat of glaze, and used a different brand of glaze. Nothing I have tried made a difference. My supplier has told me that they have not had anyone else with this problem. Most of the time there is no problem as my class usually use colored glazes. But, there are times when they want an item to be white and since we are a non profit I really don't want to use more expesive white glaze. Is there anyone that can help me? Quote Link to comment Share on other sites More sharing options...
Min Posted March 3, 2023 Report Share Posted March 3, 2023 Sounds like you are using commercial glazes? If so there really isn’t anything except trial and error to find one that is satisfactory to you. Yellow tinge is probably from trace amounts of iron in the glaze. Might be less expensive to buy a white glaze rather than trial and error testing of different clear glazes if white is what you are looking for. BTW, you can turn a clear glaze white by adding an opacifier, zircopax would be the least expensive one. Would need a glaze sieve, accurate scale and a small amount of testing to do this. Magnolia Mud Research and Rae Reich 2 Quote Link to comment Share on other sites More sharing options...
Judy SA Posted March 3, 2023 Author Report Share Posted March 3, 2023 Thanks. It sounds like something I am just going to have to live with. My seniors don' t know the difference and usually put a luster over the clear glaze. They are happy. It is mostly me that knows the difference. I'll just have to remember to use white glaze. Thank you so much. Blessings, Judy. Rae Reich 1 Quote Link to comment Share on other sites More sharing options...
Babs Posted March 4, 2023 Report Share Posted March 4, 2023 I use a white porcelain slip on red earthenware. Comes out white. Could it be the white slip turns Cream at glaze temp? A small unglazed test pot would sort that line of thought. Quote Link to comment Share on other sites More sharing options...
Judy SA Posted March 4, 2023 Author Report Share Posted March 4, 2023 If I change temperature do I go higher or lower. Do I change the greenware or the glaze firing? Quote Link to comment Share on other sites More sharing options...
Judy SA Posted March 4, 2023 Author Report Share Posted March 4, 2023 (edited) Thanks. I try that. Edited March 4, 2023 by Judy SA Quote Link to comment Share on other sites More sharing options...
Min Posted March 4, 2023 Report Share Posted March 4, 2023 15 hours ago, Babs said: Could it be the white slip turns Cream at glaze temp? Bisque is done to cone 05, glaze is done to cone 06 or 05. Could just look at an unglazed part of the pot to see the difference in the casting slip colour. Quote Link to comment Share on other sites More sharing options...
Judy SA Posted March 4, 2023 Author Report Share Posted March 4, 2023 Could the problem come from firing greenware and glaze together? Since I don't usually have enough for two separate firings I do one firing with both. Quote Link to comment Share on other sites More sharing options...
Min Posted March 4, 2023 Report Share Posted March 4, 2023 Anything is possible, it might be from firing bisque with glaze but my hunch it's less probable than being a slightly yellowish glaze colour from trace iron. Quote Link to comment Share on other sites More sharing options...
Merve Posted April 1 Report Share Posted April 1 Hi. I read your question cause I am struggling the same issue. I use standard low fire white slip 04 or 05 cone bisque and 06 cone duncan clear glaze. But my items come yellowisj. I am fed up with this issue please help me. Quote Link to comment Share on other sites More sharing options...
Min Posted April 1 Report Share Posted April 1 14 hours ago, Merve said: Hi. I read your question cause I am struggling the same issue. I use standard low fire white slip 04 or 05 cone bisque and 06 cone duncan clear glaze. But my items come yellowisj. I am fed up with this issue please help me. Hi and welcome to the forum. From Standard's website and their Lowfire Slip page there is a link with glaze recommendations. Duncan IN1001 "slightly yellow, may blur crisp underglaze lines". There are four other Mayco glaze result descriptions there also. It seems the least yellowing recommendation is Spectrum 700. Standard recommends doing both bisque and glaze to cone 04. Link here: https://cdn.shopify.com/s/files/1/0039/8177/0841/files/105-LFW_Glaze_Rec.pdf?v=1674848426 Hulk and Bill Kielb 2 Quote Link to comment Share on other sites More sharing options...
tinypieces Posted April 17 Report Share Posted April 17 I too have experienced the same issue with white clay firing yellow -ish under clear glaze. Ugh, so frustrating. While I'm not using Standard's white slip I do work with their white earthenware (STD 105). I recently discovered that same document from Standard (https://cdn.shopify.com/s/files/1/0039/8177/0841/files/105-LFW_Glaze_Rec.pdf?v=1674848426) and find it interesting. I've been using Mayco/Duncan PB001 which is on the list as compatible (crystal clear at cone 04) but it wasn't for me. That said... I did test the Spectrum 700 and was happier with the results. The clay is definitely whiter under that clear glaze. I bisque and glaze to 04. Hulk 1 Quote Link to comment Share on other sites More sharing options...
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