How hot does a cupel furnace need to be? Can it get hot enough that PMs are oxidized into bone ash cupels?

[zamistroe]

I processed a couple thousand pins that were gold plated the full length. When I got to the cupeling part it seemed that the base metals were oxidizing nicely and getting absorbed. Eventually, my button was soft, dense, and 'rose gold' in color. Did this mean there was just some copper left to go? The 'baser' base metals leave first, right? Well, fresh bone ash cupel and back into the furnace. I don't know if I turned the propane up too high, left it too long, or what, but that cupel was fully spent and also empty. What happened?

 

[snoman701]

PM's are not necessarily oxidized into the cupel, but they are drug into the cupel. Read Bugbee, Textbook of Fire Assay.

 

[Yggdrasil]

I processed a couple thousand pins that were gold plated the full length. When I got to the cupeling part it seemed that the base metals were oxidizing nicely and getting absorbed. Eventually, my button was soft, dense, and 'rose gold' in color. Did this mean there was just some copper left to go? The 'baser' base metals leave first, right? Well, fresh bone ash cupel and back into the furnace. I don't know if I turned the propane up too high, left it too long, or what, but that cupel was fully spent and also empty. What happened?

I have two questions here.
Why did you select cupelling when you have a Copper rich material?
How much in weight was these pins and what kind of pins?

 

[4metals]

Generally copper rich materials benefit from scorification in assay quantities or in production quantities some form of parting to dissolve away the copper selectively.