Jump to content
I Forge Iron

Making Nordic Gold without boiling off all my zinc


Recommended Posts

I have made a few attempts to make Nordic Gold (89% copper, 5% aluminum, 5% zinc, 1% tin).  I am having trouble with the Zinc boiling away, which boils at a much lower temperature than copper melts. I usually have the temp of the foundry at  around 2,000F - 2,200F to melt the copper.

I have tried melting all 4 metals together. 

I have tried Adding the zinc last once everything else is molten

I have tried adding melted zinc to the other 3

Every time I try to make it, it seems like a lot of the zinc boils away.  All of a sudden I get a bright flash and big plume of smoke coming out of my foundry.

I have seen some videos of people making nordic gold, but they never seem to have the same reaction that I do.  Is there some trick that I am missing?

 

Link to post
Share on other sites

Look into the eutectic melting temps of all the possible combinations and pick one with either a low enough liquidus to not boil the zinc or one that raises the zinc's boiling point enough.

You could grind them all into dust, mix thoroughly and melt it with induction in a press. 

How is that alloy "Nordic" gold? al? It must be a pretty recent alloy to contain aluminum. How do you know the final zinc % isn't residue after the rest burns off? The flash of blue green and smoke is the zinc burning, NOT boiling. 

Frosty The Lucky.

Link to post
Share on other sites

When pouring brass; we always add the zinc last, stir and pour trying to beat losing too much of it.  Of course were are doing small pours or maybe a pound and so the amount of zinc is small and doesn't lower the temp much.

Link to post
Share on other sites

There's several things to consider.  You need to allow for zinc loss before adding it.  Done right, you shouldn't lose more than about five percent.  You don't want the copper  heated beyond the boiling point, then add solid zinc at the last minute.  You may also want to cool your alloy right after dissolving the zinc, and are you using flux?  A heavy layer of flux on the surface will keep more zinc in the mix, especially since it's harder for it to burn without oxygen.

 

I don't know your experience level in casting, but you're taking precautions working with molten zinc, right?  Zinc gasses do incredibly nasty things to the respiratory system, and I wouldn't give fume fever to my worst enemy.

 

It's just Aluminum brass, Frosty, they went to using it in coins after they had so many issues with Aluminum bronze tarnishing.

Link to post
Share on other sites

I do all my melting outside and I wear a 3M 6200 Medium Respirator Face mask as a precaution.  So anytime I get a lot of fumes from anything I just step back and let it burn out.  

I don't use any kind of flux.  I have been having some better experience wrapping the zinc in aluminum foil and dropping it in to the bottom of the crucible at the last minute and them mixing it quick.  That seems to burn off a lot less.  I will also try adding some borax as a flux to help reduce the zinc exposure to air.

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...