Cupels from scratch, calcination of bone, anyone have information?

[Ragnor]

So in my never ending journey to find the gold I have finally got a smelting forge up and running, made the cone mold and I have 20 years worth of ore samples on hand. I've got all the chemicals. But I need a cupel. So I went and grabbed some cow bones and chucked them in the furnace. I let em cook for about 2 , maybe 3 hours till they turned white and brittle and nothing more seamed to be happening. I let them cool and ground them down to discover I had made a grey/white powder with some small flecks of black in it. I was rather expecting a pure porcelain white powder. That is not what I got. So I ground the powder finer and fired it again, making sure to stir it regularly to allow it to oxidize and all I got was a more uniform grey powder. I find almost nothing concerning the calcification of bone procedure online. No alchemical texts or scholarly articles, nothing. So my concern is have I done it correctly?, will the material function as a proper cupel after forming? Has anyone on here successfully performed this process or have any kind of documents listing step by step procedures and/or indications that the calcination process is moving forward correctly?

 

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[ncclaymaker]

So in my never ending journey to find the gold I have finally got a smelting forge up and running, made the cone mold and I have 20 years worth of ore samples on hand. I've got all the chemicals. But I need a cupel. So I went and grabbed some cow bones and chucked them in the furnace. I let em cook for about 2 , maybe 3 hours till they turned white and brittle and nothing more seamed to be happening. I let them cool and ground them down to discover I had made a grey/white powder with some small flecks of black in it. I was rather expecting a pure porcelain white powder. That is not what I got. So I ground the powder finer and fired it again, making sure to stir it regularly to allow it to oxidize and all I got was a more uniform grey powder. I find almost nothing concerning the calcification of bone procedure online. No alchemical texts or scholarly articles, nothing. So my concern is have I done it correctly?, will the material function as a proper cupel after forming? Has anyone on here successfully performed this process or have any kind of documents listing step by step procedures and/or indications that the calcination process is moving forward correctly?
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Calcined clay – or metakaolin – is produced by heating a source of kaolinite to between 650°C and 750°C or 1200°F to 1382°F. Kaolin is both naturally occurring, as in china clay deposits. Check your local ceramic supply for a source of calcined clay. Cow bones... easier to use bone ash from a pottery supplier. I was a ceramic artist for over 20 years. Try adding a small amount of Portland cement as a binder/adhesive to the bone ash. Cure in a mold.

 

[russau]

GREAT comment / post !

 

[Ragnor]

Calcined clay – or metakaolin – is produced by heating a source of kaolinite to between 650°C and 750°C or 1200°F to 1382°F. Kaolin is both naturally occurring, as in china clay deposits. Check your local ceramic supply for a source of calcined clay. Cow bones... easier to use bone ash from a pottery supplier. I was a ceramic artist for over 20 years. Try adding a small amount of Portland cement as a binder/adhesive to the bone ash. Cure in a mold.

Thanks for the info, I found the bone ash to be quite delicate and crumbly, I will definitely try a binder.