TS Studio Posted September 17, 2015 Report Share Posted September 17, 2015 I'm looking for your best cone 10 OXIDATION satin matte black food safe recipes. Any suggestions are greatly appreciated. Link to comment Share on other sites More sharing options...
High Bridge Pottery Posted September 18, 2015 Report Share Posted September 18, 2015 I think that is a very hard glaze to find. Even if you get a recipe, to fire it 'food safe' will require a fairly exact firing schedule. Having a high colourant semi matte glaze it sounds so easy to leach out metals and discolour in use. To get a safe satine matte I feel you are having to get many crystals surrounded in a glassy phase which is borderline devitrified. If the surface is not vitrified/glassy then it will mark and probably leach. Keeping it there and not going too far in either direction is the skill. This has been my experience anyway. Never tried for a black satin matte but I have searched for a clear/white one. Hardly looked into slow cooling which I think is part of the skills needed for plenty of crystals surrounded by glass. Link to comment Share on other sites More sharing options...
Mark C. Posted September 18, 2015 Report Share Posted September 18, 2015 I have one-that I have used for 30 years in large quanities Zacks black-named from the 1st large order (Zack was the customer)I had with this glaze Nepeline syenite-900 alberta slip-1980 cobalt oxide -105 This will look gunmetal if fired cone 9 and gloss up at cone 11 you will have to find your sweet matte spot-my guess cone 9 1/2 works in reduction or oxidation-very dependable-no flaws it will go blue if diluted with other glazes It expensive with all that cobalt but worth it. I mix this glaze every month in larger 10,000 gram batches-its looks great under glazes as well. This glaze is only oversaturated with If i recall 3.5% cobalt ox Mark Link to comment Share on other sites More sharing options...
Guest JBaymore Posted September 18, 2015 Report Share Posted September 18, 2015 The first task you have in this pursuit is actually defining what YOU mean by "food safe". There is no "legal" definition (in the USA) of that term, even although potters tend to toss it around like there is some single ASTM standard for it. What you are basically looking for is physical durability and chemical stability of the fired surface. Within that above criteria, a semi-gloss surface and also a black color. Physical durability, chemical stability, and black is not all that difficult. It is that "semi" surface part that brings in the potential issues. It is like you can easily have three of the four...... pick the three you want the most . For getting the black color...... use a commercial glaze stain not a super saturation of metallic oxides. For durability and stability... get the silica number as close to upper molecular limits as you can, as well as also maintaining high alumina numbers. Not saying it can't be done.... just that it is not easy. Lots of testing work coming up for ya'. Including lab leach testing. best, .....................john Link to comment Share on other sites More sharing options...
TS Studio Posted September 18, 2015 Author Report Share Posted September 18, 2015 That sounds like a slight variation on St John's Black. I like that glaze but it's not quite right for this line of production. I have one-that I have used for 30 years in large quanities Zacks black-named from the 1st large order (Zack was the customer)I had with this glaze Nepeline syenite-900 alberta slip-1980 cobalt oxide -105 This will look gunmetal if fired cone 9 and gloss up at cone 11 you will have to find your sweet matte spot-my guess cone 9 1/2 works in reduction or oxidation-very dependable-no flaws it will go blue if diluted with other glazes It expensive with all that cobalt but worth it. I mix this glaze every month in larger 10,000 gram batches-its looks great under glazes as well. This glaze is only oversaturated with If i recall 3.5% cobalt ox Mark Link to comment Share on other sites More sharing options...
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