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Palladium White inquires

#1

Hello everyone,

At some point it will be time to upgrade from silver to white gold, however I would like to know what to expect in regards to this upgrade sooner than necessary. I plan on alloying the gold myself, with pure palladium, silver and copper with around 16% palladium in the finished alloy to have a nice, warm, steely grey colour and avoid the yellowish-brown of low palladium alloys. I am not averse however to using palladium master alloys, although I would prefer higher palladium content (50+ percent palladium) I am concerned about the melting point, will I need a different ingot mould than cast iron? Will I need a crucible designed for platinum work? Would I season this crucible as per usual (because I am working with gold, not platinum) if I do use a platinum crucible? Are there any other things about palladium white gold I should know before attempting this?

Additionally, would a smith’s little torch be sufficient for the alloying and melting of the finished gold or would I need a different torch. If so which one? Hydrogen is not an option, I use propane and oxygen. Thanks for any input,

ArgentumMoon

#2

Some thoughts on your questions:

  1. I think 16% is too high. Better at 13%. ‘Maybe’ 14% tops!. Same % palladium for 14K or 18K.
  2. Use a graphite mold. Too hot for cast iron.
  3. Don’t use a clay crucible. Only use a fused silica crucible. The melt temp for what you’re doing is pushing the limits of clay. Use the smallest crucible you can and rest it on a charcoal block or fire brick.
  4. No on the Little Torch. Will not produce enough ‘concentrated’ heat BTU. Smith, Victor, Gentec, etc., make Torches a little larger than the Little Torch (AW1A Torch body for the Smith) that would be better allowing more gas volume and a larger flame for small melts.
  5. You’re correct re: not using hydrogen with palladium due to embrittlement issues. Hydrogen / oxygen is ideal for platinum and some other precious metals but not palladium alloys.
    Good luck!
#3

Thanks for the reply, lots of good info there. I checked my supplier and they recommend not going above 1530 degrees Celsius for thier fused silica crucibles. Pure palladium melts at 1554 degrees, should I use a Morgan melting dish (wesgo) for the initial alloying, and if so should I season the crucible with borax as per usual?

In regards to the torch, have you ever used a meco midget? Do believe it would possess the “firepower” necessary for this purpose.

#4

1.The crucible you asked about is what I recommended. Also referred to as a Morgan Wesgo crucible. Used for platinum melting and is required for the high temps you need.
2. Do not use borax in this case. A good idea is to coat the crucible / melt dish on the inside only, before first use, with zirconium oxide (ZrO2) paint. Available from Gesswein and others. Can be painted or sprayed on.
3. We have used used the Meco for many years. A great, small soldering Torch but not what you need in this situation. Many people believe small Torches like the Meco (a very good Torch) and Little Torch will ‘do everything’ but they were not designed for some uses.

#5

My appologies for reading your original post too quickly! I thought you’d said 26% palladium rather than 16%. I’ll change my suggestions: (I think 26% is too high) Between 13% to 24% ‘tops’ is O.K.
All things considered re: this project I’d recommend buying a master alloy. Using high cost precious metals gets expensive when mistakes are made. Yellow gold alloying is fairly easy. Palladium & platinum alloying is not so forgiving.

#6

Thank you for all the information. It has been very helpful. :slight_smile:

#7

Would it be detrimental to coat the Wesgo crucible with borax? Would I use borax as a flux afterwards as this is a gold alloy?

#8

Follow-up to your questions…

  1. Coat the flask with ‘ZO’ compound first, before using any borax. ZO coating creates a seal so contaminants don’t get to the melted metals.
  2. Flux is not generally needed with a Pd master alloy but ‘just a pinch’ can be used if necessary.
  3. The Pd percentages I mentioned earlier applied to making things from ‘scratch’ vs. using a master alloy. Pd percentage in the master alloy are usually much higher. The master alloy might range from 20% to 59% Pd.
    Different refineries have different formulas, often proprietary. Master alloys are also formulated for casting grain and fabrication / rolling alloys so be sure to inquire.