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Showing results for tags 'defects'.
Hi everyone, Hobbyist ceramist with a few years of experience here, but not so much glaze chemistry knowledge. I make work at a studio in Germany since a few years and since the summer, we noticed a lot of new issues with various glazes used at the studio. Nothing seems to have changed a priory with the way we do things. We fire with 2 different Rhode ecotop kilns at 1220 celcius. All ours work is made using a white stoneware clay from one distributor. We order commercial glazes from the same distributor and a few other glazes from another one. We've been using the same glazes for years and the same firing cycle as well. We received a new order of clay and glazes in August from our main distributor and since that, we started to notice an increasing amount of dunting. The issues are mainly with work from beginner students that are taking classes at the studio and that are perhaps applying glazes a bit too thick. This is something that happens regularly but didn't usually result in dunting before. Then recently, I also started to have shelling or slight shivering issue at the rims of cups on some of my own pieces when using one particular glaze. It's a matte transparent glaze I've been using for years and never had issues with. Is it possible that it is the clay body that is creating all these new issues? What is the best way to trouble solve from here? I emailed both distributors so ask if they know of any changes with their products already ( waiting on an answer) but any other tips I can get from someone with more experience would be much appreciated!
Hi all. Am having trouble with pinholes. I am using some commercial glazes and one glaze I mixed up from a recipe I found online. I clean my pieces very well before I glaze. I allow to dry before glazing, and leave them covered until glazing. I believe maybe it could be my one glaze recipe, or perhaps it could be the firing. I rent a space and the owner does the firings. He will not let anyone else fire and he blames all defects on you or your pots. Any help is so much appreciated. I am attaching a photo of a bad example of a glaze with a pinhole I got this firing. I saw where I could add flux, or remove zinc or rutile? Here is my recipe for floating blue cone 6 I used: Neph Sy - 45.2 Gerstley Borate - 24.5 Silica - 18.9 EPK Kaolin - 5.7 Whiting - 3.8 Talc - 1.9 Bentonite - 2 Rutile Flour - 4 RIO - 2 Cobalt Carb - 1