Romix
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Gold precipitate melting temperatures NaSO3, FeSO4
Hello Dear forum members, here is another question for you.
Why gold precipitated with NaSO3 melts very quickly with any cheap Chinese torch lighter in minutes.
Gold precipitated with FeSO4 melts only after heating it up with a MAPP torch for like 5 minutes. It is almost impossible to melt gold precipitated
with FeSO4 with normal butane.
  
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Romix
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Maybe because gold is dirty? That's why it requires higher temperatures?
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Romix
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Pure gold melts easy by the gram with any cheap butane jet torch.
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Rainwater
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There are several factors affecting the melt. Assuming you have a perfectly pure sample, these include the size of your melt dish, how the dish was
waxed/seasoned
And most importantly, any heatsinks.
Example,
holding the melt dish with steel tongues will suck heat away so fast your sample cant melt.
Placing the melt dish on a hard firebrick will have the same effect to a lesser degree.
Soft brick - same to a lessor degree.
K wool, is what ive started using. Pretty much stops conductive heat loss,
With any impurities the melt temps change a lot.
An alloy of 6 parts gold, 1 part copper, 1 part tin has a melting point of 650c. Its 18c gold solder.
With an iron impurity id imagine the melt temp would increase
"You can't do that" - challenge accepted
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Romix
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Maybe you are right.
I used a crucible made out of nickel, and it cools very quickly.
That could be the reason.
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