Diana Ferreira Posted July 13, 2012 Report Posted July 13, 2012 Hi there Ok, first thing. I live in South Africa. There is no way that I am ordering clay from the USA! I am also very stingy, and would not mind to save some $$$ making/mixing something myself. I buy my glaze wholesale these days, and was shocked when I discovered that it is about a 1/3 what the supplier charged me ... I have been using a terracotta based slip with added oxides for the last year. But it gives me a lot of added on labour, as I have to sand each piece after a bisque firing to get rid of the roughness. Another supplier gave me a bucket of his black stoneware slip, and I love the smoothness of it. But the price is scary. I will have to add another 10% on my annual price rise, if I go this route. My customers will be unhappy ... Does anyone know what oxides to add to a white clay body to turn it black after firing? And the quantities? I would really appreciate it.
Guest JBaymore Posted July 13, 2012 Report Posted July 13, 2012 How true a black do you desire? Do you care about potential added studio working toxicity issues? Do you care about potential leaching of toxics relative to functional wares? best, .......................john
Chris Campbell Posted July 13, 2012 Report Posted July 13, 2012 I use Mason stains ... Best Black ... I think the number is 9900. If you want a black exterior you might want to try making a slip from the clay you are using for the wares and color it with 10 - 15% stain. This would be cheaper than coloring all of the clay.
Diana Ferreira Posted July 13, 2012 Author Report Posted July 13, 2012 hi John I know that the suppliers add manganese to the slip. I am aware of the fumes from firing, but we have extraction fans in the studio. I wet sand, and wet sweep my working area. I have read all the technical info I could lay my hands on with my clay and it's content. But, I want true black.
Diana Ferreira Posted July 13, 2012 Author Report Posted July 13, 2012 Thank you Chris. that is an option. I really love the black that I have. But I also have issues with the clay, and a lot of stains and glazes does not like the metal content of the clay.
Guest JBaymore Posted July 13, 2012 Report Posted July 13, 2012 I'd then go with ceramic body stains (like Chris mentioned) rather than oxides. A tad less toxicity issues. Manganese is (unfirtunately) the "go to" colorant for black clay bodies. And as far as the 'extraction fans"........ fine .... but have you done any air quality studies to KNOW that those fans are actually doing the job.... not just whirring away? best, .......................john
Iforgot Posted July 18, 2012 Report Posted July 18, 2012 If you are not worried about food safety you can use a hefty amount of black copper oxide, i think most pottery suppliers carry it, also www.axner.com has wonderful prices on raw materials, and global shipping . good luck!!!!!
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