Hi, I am new here, thanks for having me. Please could someone help me to learn how to clean & smelt Platinum filings. At this point I am keeping my filings separate from my paper and rubber wheel dust. Thank you.
I don’t have any experience with smelting platinum fillings in a small studio, but as far as I know it’s complicated. The closest I’ve come is torch welding platinum rings to size them. It will be very interesting to hear what others say.
As far as I know, it’s going to be best to return your platinum filings and scraps to a refinery to be professionally refined.
Like I said, let’s see what others say. Thanks for asking and welcome!!
Thank you for your time. I need to return my worked metal filings back to a metal supplier in solid form. I am making a piece for a competition, they loan me the metal and I must return everything. They allow a 5% loss, but I would like to return as much as possible so as not to be charged for any extra loss. I have tried to find information, but really can’t find much. I must say though that I am loving working with Platinum.
I did a little reading on this and found that you need an oxidizing flame for malting platinum. You also need to use a silica rather than a graphite crucible, so there is no reducing atmosphere, which is what the graphite crucible is for. As fuel, hydrogen is best (water torch), but natural gas or propane would also work. It takes a nigher temperature than gold or silver. I would assume that any organic material would burn off in the melting process. But it might be hard to deal with a small button of platinum, too. I think you’d have to finish the project and weigh it and the scraps and compare that to the original weight. Then you could see what your filings are worth and decide whether getting the equipment together to try to melt them is worth it. You could call a metals refinery and see what is the minimum they will deal with. Altho’ it seems cumbersome, you could possibly send your filings off to a refiner which would take them for credit and use that money to offset any loss charged against you. -royjohn
Okay, I think we’ve got it figured out here. What I’m reading into what you wrote is that you need to melt all of your filings and scrap into one solid platinum blob. That you don’t need to refine it, just melt it all together. Is that correct?
royjohn is correct with the type of torch that you need. I’m guessing that you already have a torch that will melt platinum, since you’re working with it.
Platinum melts at 3200 F. That’s substantially hotter than what any conventional jeweler’s soldering block can take. (1700 - 2000 F is the standard max temp for gold and silver soldering blocks) Probably the least expensive thing to acquire then to melt your platinum bits in is a platinum specific casting crucible.
Here’s a couple of options
Here’s a .pdf from Rio Grande about platinum casting. It says that you don’t need any flux. Just melt it. As long as you have the proper torch, it sounds sort of straight forward.
I’m sure you know this, but you’re going to need some seriously dark specialty safety glasses! Don’t melt the platinum without them! I can’t emphasize that enough!! For soldering platinum you need #5 or #7 shade lenses. For melting platinum you need #10 shade lenses. (I’ve read conflicting info about #7 or #10 shade lenses for melting platinum, I’d go with shade #10).
One final thing. Be very careful!! 3200 F is really, really hot. Make sure that your platinum crucible is on a fire brick and on a heat proof table. Wear #10 shade lenses, leather gloves, cotton or wool clothing. After you melt the platinum don’t quench it. Let it air cool.
This is one of those things that will take more prep time than actually melting the metal. But it will be worth it to do it right.
My husband TimothyW Green and I are old, (and I mean really old), school platinum hand fabricators. We always cleaned platinum of debris and solder by boiling it in aqua regia. This procedure is very dangerous and should be approached with extreme caution. In one of our studios it ate the metal blades of our exhaust fan. “Do not try this at home kids!”
Jo in doing your platinum fabrication work, did you ever melt your scrap together for some reason? I’ve melted platinum often when resizing platinum rings, but I’ve never melted platinum scrap together. To do that it needs to be on a proper surface.
I was surprised to see that I couldn’t find a soldering block capable of melting platinum. That’s why I recommended a platinum casting crucible.
Any advice for HeidiM68949 that I might have missed?