Blowing Rock Pottery Posted May 26 Report Share Posted May 26 the mug on left is WFB over Spearmint. Cone 5, slow cool, 04 bisque. Problem is pinholing when glazes overlap. This is new issue, been doing this combo for 20 years, no problem (when fired to cone 5, 12 minute hold, natural shut off.) would like any help and also a firing program. Thank you! Quote Link to comment Share on other sites More sharing options...
Min Posted May 26 Report Share Posted May 26 Hi and welcome to the forum. What has changed? New supply of one of the materials, claybody? Could you post a closeup of the problem? Quote Link to comment Share on other sites More sharing options...
Blowing Rock Pottery Posted May 27 Author Report Share Posted May 27 14 hours ago, Min said: Hi and welcome to the forum. What has changed? New supply of one of the materials, claybody? Could you post a closeup of the problem? Quote Link to comment Share on other sites More sharing options...
Blowing Rock Pottery Posted May 27 Author Report Share Posted May 27 Hi , thanks, I’m excited to be in forum. If you zoom in on the bunny mug, you can see the pinholes, and yes I will post another picture tomorrow. I’ve been doing the same combo of the two glazes for 20 years, WFB over spearmint. I do have a new kiln, but I’ve fire to cone 5, 5 minute hold, controlled cool down. The problem seemed to be solved, then it started again. I think I need a new program for firing WFBrown. Ancient Jasper is also pinholing. I do a bisque to 04 and have bought new glaze chemicals from Highwater clays, and I follow the recipe in Mastering cone 6 glazes mainly applied to speckled brown clay. thanks for your help Quote Link to comment Share on other sites More sharing options...
Min Posted May 27 Report Share Posted May 27 When I zoom in on my iPad I'm seeing blisters but the image isn't really crisp so not sure on this. Are you getting the problem with your white clay also or just on the brown speckled clay? Is rutile one of the materials that you have bought a new supply of? If so does the spearmint contain the new rutile? What is your controlled cool down schedule? Pres 1 Quote Link to comment Share on other sites More sharing options...
Blowing Rock Pottery Posted May 28 Author Report Share Posted May 28 Hi there, pits on white and brown clay, and yes both the Spearmint and Waterfall Brown glazes contain rutile. I had bought a new bag of light rutile over the last year, (or two) right about when the problem showed up. My cooling program is 150 an hour to 1400 degrees. I go to cone 5 With a 5 minute hold. I think you are on to the problem, much appreciation. having trouble sending you picture within the total size allowed. Quote Link to comment Share on other sites More sharing options...
Min Posted May 28 Report Share Posted May 28 (edited) 2 hours ago, Blowing Rock Pottery said: having trouble sending you picture within the total size allowed. Try emailing it to yourself and then try posting that image. Rutile changes can definitely cause pinholes/blisters, would be one of the first things I would test for. If you have some titanium dioxide I would suggest mixing up a couple hundred grams of both bases and sub titanium dioxide for the rutile. Glazes will be missing some of the trace elements found in rutile (that are missing from titanium dioxide) but it likely won't make a significant difference to either glaze. For the Waterfall Brown use 0.90% TiO2 in place of the 1.00% rutile and in Spearmint use 5.35% TiO2 in place of the 6 rutile. (I took the rutile amounts from the recipes as published on Glazy) It's usually best to just change one variable at a time. edit: you verify your glaze firings with cones, correct? Edited May 28 by Min Kelly in AK 1 Quote Link to comment Share on other sites More sharing options...
Blowing Rock Pottery Posted May 28 Author Report Share Posted May 28 Thanks soooo much. Yes I use witness cones. More on that later , I have two kilns, and they act like two different children ha ha Hulk 1 Quote Link to comment Share on other sites More sharing options...
Blowing Rock Pottery Posted May 28 Author Report Share Posted May 28 Hence I put three layers of cones in, top to bottom. Quote Link to comment Share on other sites More sharing options...
Min Posted May 28 Report Share Posted May 28 1 hour ago, Blowing Rock Pottery said: I have two kilns, and they act like two different children ha ha LOL. I've found glazes sometimes behave like children, some just don't want to play nicely. Others have issues interacting with others. Some think they are princesses and need special attention. Some will just hunker down and sulk and not move while others want to run all over the place. Mother of 4. Callie Beller Diesel, Kelly in AK and Hulk 3 Quote Link to comment Share on other sites More sharing options...
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