Boudi Posted August 31 Report Share Posted August 31 Hi I have a fair amount of stoneware glaze in powdered form and I want to use it for earthenware firing. I don't have the recipe but understand I can add flux to lower the melting temp. I would really appreciate some help/advice. I am in the UK and know that things are slightly different here in terms of names of chemicals etc. but hoping someone can help me. Quote Link to comment Share on other sites More sharing options...
Dick White Posted August 31 Report Share Posted August 31 The usual way glaze recipes change from cone 6 to earthenware is by the addition of boron oxide to the chemistry. Boron is technically not a flux element, instead it has such a low melting point (relative to the other materials in the glaze) that it draws everything else into its own melt until it is all fluid. Your most likely source for additional boron is a boro-calcia frit. If you don't know the recipe, you don't know how much frit to add, so you will have to test adding measured amounts until the glaze finally begins to perform as desired. Bill Kielb, Hulk and Boudi 3 Quote Link to comment Share on other sites More sharing options...
PeterH Posted August 31 Report Share Posted August 31 Following on from Dick's suggestion Hulk and Boudi 2 Quote Link to comment Share on other sites More sharing options...
Boudi Posted August 31 Author Report Share Posted August 31 Hi Thanks for your replies, I have been reading more about it. I can buy various forms of boron in the UK: Borax (Decahydrate Borax) Borax frit Soft borax frit Possessing a higher flux content than standard borax frit, this frit will produce more alkaline colours without crazing. I am wondering which to buy. Or maybe I should get all 3 and see the results. I was going to add 0.5%, 1%, 2% 3%, 4% and 5%. Do think this is a good starting point? I am not good at chemistry and the more I read, the more complex it becomes. Quote Link to comment Share on other sites More sharing options...
High Bridge Pottery Posted August 31 Report Share Posted August 31 Calcium borate frit will give you the most boron in frit form. It disappeared for a few years and then came back at twice the price https://www.potclays.co.uk/calcium-borate-frit You may be better trying to resell what you have and buy an earthenware glaze. I make cone03ish glazes and they are 85-90% frit and 10-15% china clay. Chilly, Min and Boudi 3 Quote Link to comment Share on other sites More sharing options...
Boudi Posted September 1 Author Report Share Posted September 1 Hi Thanks for your advice, yes, I will probably be better off just making some work in stoneware to use the glaze. I am still running a little experiment though.🙂 Hulk and High Bridge Pottery 2 Quote Link to comment Share on other sites More sharing options...
High Bridge Pottery Posted September 1 Report Share Posted September 1 Always good to experiment I know there's some glazes that are pretty happy with a wide firing range so maybe you will get lucky and 5% frit addition will do it. Quote Link to comment Share on other sites More sharing options...
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