Cupellation – from cupel to SILVER bead

Cupellation – from cupel to SILVER bead

warning this video is intended for demonstration purposes only trying to duplicate the shown procedures may result in serious injury or even death the most elaborately accurate but totally destructive precious-metal assay is fire assay cupellation is a refining process in metallurgy where ores or alloyed metals are treated under very high temperatures and have controlled operations to separate noble metals like gold and silver from base metals like lead copper zinc arsenic antimony bismuth the process is based on the principle that precious metals do not oxidize a react chemically unlike the base metals so when they are heated at high temperatures the precious metals remain apart and the others react forming slags or other compounds Cupel a shallow a porous container in which gold or silver can be refined or assayed by melting with a blast of hot air which oxidises lead or other base metals. I make the cupels from dry Portland cement compacted in a stainless steel measuring spoon for this video we’ll be refining some silver contact points for that purpose I’ll fuse the contact points with lead I am using a small propane torch as a heat source the cupola is preheated before placing the contact points and the lead as the temperature rises the contact points are slowly dissolved by the lead when the fusion completed the flame was positioned away from the centre of the cupel, pointed to the side creating tangent airflow above the molten lead the lead opens up and begins to drive at some point the buttons stop driving and it froze. This usually happens when there is too much copper present and the lead is absorbed by the Coupole before all copper is oxidized The solution is to add more lead the flash – a sudden brightening of the bead and disappearance of the red lines and their replacement by a rainbow is a sign that the cupellation is almost complete after sometime the rainbow disappears uncovering bright silvery mirror like surface the cupellation is complete and the button is left to cool viewed from the top I didn’t like the finishing of the bead so I’ve added a tiny amount of lead and continued cupelling one more time finally I’m happy with the result thanks for watching please don’t forget to Like comment and subscribe below


  1. Cool video. However burning lead and making fumes ..for me just won't work… I just refined a kilo of silver and used nitric…thanks for the videos buddy😁

  2. Классное видео! Объясни что это за песок и напиши что ты конкретно делал?

  3. Thanks for sharing !
    I usually add 3 times the initial weight with lead ( Like inquartation )
    This let me free time to do sth else while processing…
    Like trying to recover my first stock pot…
    Challenging a PH9 mixed solution…
    Wish me good luck on it ! 😀

  4. Okay… I found most information here.
    But WHY do you have to dilute the precious metals with lead first when you actually want to purify it?

  5. какую минимальную температуру должен создавать факел пропана , чтоб окиси забирались цементом ?? , у меня при 400 – 500 по Цельсию все шлаки остались в купели

  6. hi! thank you for the video! i know almost nothing about metallurgy except for what im learning at high school, so i wanted to ask, how long can you keep adding lead to purify the silver? is there a limit to doing that?

Leave a Reply

Your email address will not be published.