Thanks for the reply. I'll fill in as much as I can right now, with more answers to come...and likely more questions too.
I don't have the weights of the lead I am using with me right now. That's all at the office. I am currently using lead foil that is 3" wide which I usually cut into 1.5" x 1.5" squares and wrap my samples up in that. I had actually also quartered those thinking that perhaps I had too much lead. Now I am wondering if I don't have enough lead to pull away the other base metals during cupellation.
The bullion is primarily gold. Responses from the other assayers usually put it at around 55% gold and 7% silver. The pin samples I begin with are about 1.5g which I then separate into three sort of equal parts. I take the weight of the separated sample, multiply it by .553 (the average Au typically found) and then multiply that by 4 to get the amount of silver to add. Probably too much silver, I'm sure but what I had read is not enough silver meant separation in Nitric would be difficult.
Did not know about adding copper. So that's something new to me.
As far as ventilation, there is a top vent on the furnace, but as I've been reading more, I should have the door ajar to let more air in. And seeing the "blick"...nope...I'm usually involved in a dozen things at the time I'm running these so I toss the cupels in and give it a bit then come back. I've never read an expected time for them to be done, and even though I've read about the "blick" I don't think I've ever witnessed it.
To fill you in, I work for a
very small company that buys the scrap gold from the jewelry stores and other dealers in the area and takes the larger batch to the refiners. Typically we run a 200ozt bar about once a week and we send a separate pin sample to a third party assayer to keep the refiner honest. We're looking to reduce that by performing our own assays, and in cases of variance then using the other assayer as an umpire. I also understand that I'll soon be learning how to perform Aqua Regia refining in the year to come so that we'll be sending down already refined gold and getting a higher percentage of spot. The boss likes to make sure I don't get bored.
So, basically I'm squeezing learning how to do assays in between hammering out the handles on knives, sorting the silver we've received and testing the gold that's come in. I did just order a couple of books strictly on assaying that I saw mentioned on this forum, and I'm hoping that they'll fill in some of the blanks. But I'll be honest, I feel like I'm walking around a furnished room with the lights out, and my shins are getting pretty bruised.