Jessicak Posted November 8, 2020 Report Share Posted November 8, 2020 Hi guys, I’ve just made a set of bowls using the spectrum 250 satin clear glaze. It’s on Draycott White Stoneware 1143 mixed with 3.5% best black mason stain. I fired up to 1200 with a 20 min soak. I was expecting a clear glaze with a slightly matte finish, but instead got this beautiful pool of blue at the bottom. I’m guessing this is something to do with the glaze running down the sides of the bowl and pooling at the bottom. I had some plates with the same glaze on, and they are all clear. I love it, but I’m concerned that with the crazing that’s developed in the base that these won’t be food safe. These are functional wares, so I’d like to keep the blue pool but remove the cracks. I have never mixed my own glazes so would be a complete novice in adjusting the formula. If anyone has any suggestions, I’d be most grateful! Link to comment Share on other sites More sharing options...
Bill Kielb Posted November 8, 2020 Report Share Posted November 8, 2020 1200 c would be cone 5-1/2 ish and spectrum 250 is a lowfire cone 06/04 ( Prox. 990c - 1060c) glaze. Your stoneware advertises 1200c - 1300c which is cone 5-1/2 to cone 10+. First thing would be to establish a matching clay and glaze combination, maybe midfire cone 6. For functional ware pick a clay that fully vitrifies at that cone and pick glazes that are made to fire to that cone. Right now, nothing you have matches. The glaze will simply overfire, melt and likely run at this temperature. Link to comment Share on other sites More sharing options...
Jessicak Posted November 9, 2020 Author Report Share Posted November 9, 2020 15 hours ago, Bill Kielb said: 1200 c would be cone 5-1/2 ish and spectrum 250 is a lowfire cone 06/04 ( Prox. 990c - 1060c) glaze. Your stoneware advertises 1200c - 1300c which is cone 5-1/2 to cone 10+. First thing would be to establish a matching clay and glaze combination, maybe midfire cone 6. For functional ware pick a clay that fully vitrifies at that cone and pick glazes that are made to fire to that cone. Right now, nothing you have matches. The glaze will simply overfire, melt and likely run at this temperature. Can’t believe that didn’t even cross my mind. I am thinking that the blue pool I have will be a result of the glaze melting and running. Any way you think I could achieve that without over firing? Link to comment Share on other sites More sharing options...
Bill Kielb Posted November 9, 2020 Report Share Posted November 9, 2020 Folks do get good at these looks using runny glazes. It’s an acquired talent usually using a known runny glaze or glaze combinations. They generally get very skilled at controlling the drips and safeguarding other wares and their kilns. Jim brown blue is a glaze I can remember runs a bunch but folks got proficient at edge dipping etc..... Link to comment Share on other sites More sharing options...
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