Pd and Pt soldering

[Les Riddell]

not sure if this has ever been covered but... ive been doing some work in platinum this week and thought that i should put on this tip for all of you that would like to construct in platinum and palladium.. work suspended from a third hand and do not use flux of any type when soldering. also use a very concentrated flame that is oxidizing (more oxygen) when casting or making wire use a clean melting dish with no flux and and an oxidizing flame. these materials are very easy to work with. have confidence and go for it.

 

[James Roettger]

I've rolled ingots successfully from platinum but with palladium it just cracked up when I went to roll it. Used clean crucibles etc and could not recycle palladium. Platinum is easy and should only be done with a fused silica crucible. I was told regular ceramic crucibles will contaminate the platinum and of course those type of crucibles melt at that temperature. If anyone has made palladium ingots successfully I would love to hear the details. I'm not a big fan of palladium, the seams are weak as far as my experience goes. I've had seams crack after I started working on the piece. Also palladium seems to become embrittled from the high heat required to solder it using palladium solders. I switched to 18K white gold solders as I get more durable seams with it than palladium solder. I once worked on an antique palladium ring from the 40's and was surprised to find it put together with gold solder. I took it as a solution to the brittle seams I was getting.
I have had trouble getting good info on palladium. I've read Hoover and Strongs tech tips as well as Stuller's. As far as I can tell it doesn't work that well in terms of solder seam strength. I like it for castings but find myself worrying about having to size rings and having brittle sizing seams. I think there is a reason palladium is not a mainstream metal and that is it's limited workability.

 

[diandwill]

When I melt platinum, to make wire etc., I use a charcoal block. I cut a groove in it and melt the platinum until it fills the groove. Then I can make into wire or narrow sheet. If I need wider, I buy it.

I don't/haven't used palladium. Most of the jewelers I've talked to have had problems with soldering. The answer apparently, is laser welding. The PUK 3 or Orion is a $4500-$5000 device that can substitute for the much more expensive machines, but even they are out of my budget at this point. I hope to get one, not for palladium, but for quick chain repair and re-tipping, plus eye glass repair etc.

Will

 

[James Roettger]

Are you sure it's not white gold you melted on that charcoal block? I never would have thought a charcoal block derived from a piece of wood could withstand the heat of melting platinum. I would expect complete vaporization of the block from the oxidizing flame and white hot temperatures. Sort of like the "China" syndrome talked about when a nuclear plant melts down. Why doesn't it burn away? I would be concerned too about carbon contamination using charcoal as I was told years ago by a great platinum smith to stay away from graphite crucible material warning of carbon contamination and embrittlement. This is why hydrogen is recommend over acetylene because of the carbon issue. I usually melt platinum on the back side of a round fused silica crucible. I grind a groove into the crucible back, then lay the platinum scrap into that and melt with an oxygen-hydrogen torch. Just after the ingot melts and forms and is still white hot I flip it over with a clean tungsten carbide solder pick and glaze over the back side to smooth it. Before it cools I then lift it again with the pick and scoot it to a cool area of the crucible so it doesn't stick to the slightly molten tacky surface.
With palladium I used a propane oxygen torch as my reading/study said to stay away from hydrogen. Again my results with palladium recycling were not successful.

 

[Les Riddell]

for palladium remelts i use a platinum silica crucible and heat up my ingot mold to about 550 celcius. i have had no problems with cracking as long as im careful to use clean material. you can gas weld palladium using a bit of the parent material to get a good join. object must be suspended and be careful not to contaminate. also you can add between 5 and 10% fine silver or gold to you remelts, this brings down the melting temp and increases the temperature difference between melt flow and getting it to hot. you can still use palladium solder for joining and i have even used platinum solder with it as well. i use alloys that start at 75% palladium using fine silver or fine gold without cracking issues in forming and will cast well in a centrifuge.

 

[Mike Cirelli]

You cannot weld pldwith a torch it will crack and pit, you may be able to us a laser I don't know. It solders very well though. Most metal suppliers have an array of solders for pld now. I us a hard for sizing rings and it solders beautifully. Do not flux or fire coat as that will contaminate the solder joint. You also need to us a fairly agressive oxidizing flame.

 

[diandwill]

Are you sure it's not white gold you melted on that charcoal block? I never would have thought a charcoal block derived from a piece of wood could withstand the heat of melting platinum. I would expect complete vaporization of the block from the oxidizing flame and white hot temperatures. Sort of like the "China" syndrome talked about when a nuclear plant melts down. Why doesn't it burn away? I would be concerned too about carbon contamination using charcoal as I was told years ago by a great platinum smith to stay away from graphite crucible material warning of carbon contamination and embrittlement.

Quite sure it is platinum, I have to wear welders goggles as it will burn the retinas without, and also pretty sure that black block, wrapped in wire, is charcoal. It gets to a very bright red glow, and you can't reuse the same section, but I've had no problem with contamination, or a nuclear meltdown, yet...but if you see a mushroom clowd over Spokane, I hope it wasn't me, but I won't be worrying about it at that point.

 

[jldj]

When I apprenticed at Picken's Inc. in Atlanta, they used Palladium as a Platinum solder instead of the Pt 1700. They just rolled down the Palladium sizing stock from Hoover and Strong into very thin strips (more thin than regular solder) - used spit on the hand then dipped the Palladium in it to stick to the Platinum - then fired it up - hot and fast. Joints held very well with an almost imperceptible seam after polishing.

 

[James Roettger]

Diandwill I did try a tiny piece of platinum on a charcoal block and was surprised to see it withstand the temperature. It didn't absorb a lot of heat the way a silica crucible does. I did notice the back side had some charcoal black on it. Don't know if it went in to the platinum. Could probably glaze the back side clean. I'll probably stay with the silica as it seems cleaner.
I have not tried cutting the palladium down with silver, sounds interesting.
To remelt the palladium I used an oxy-propane flame on a silica crucible with fresh new metal and it cracked like crazy when I tried to roll a square wire from it. I got the new palladium from Hoover and Strong several years ago. I also bought the palladium solders. On one project a large long seam cracked after I was working on the piece. It seems like the stuff doesn't like the heating and cooling process around seams. I like the color of the metal and would like to find a way to make more inviting like being able to recycle it. I don't want to have to scrap the leftover bits back to the refinery.