My melted 24k has pink film

I melted new 24k in a silica graphite mold and when it cooled it had a pink film over part of it.

How do I get rid of it and not have it happen again?

Thanks,

Barry

How did you melt it?
The film has only three places to come from as far as I can see.
The melting crucible
The Mold
Or that the 24 karat is not 24 karat.

From the picture it looks like some kind of flux, like borax or such.
Pure gold do not need borax or flux.
If you use a melting dish, it should be pre-glazed with borax that is all.
If it is borax then dilute sulfuric or hot water will fix it, but it takes time.
If there are impurities in the Gold some use a pinch of Nitre on the metal just after pouring.
That will remove surface tarnishing, but will not do anything withe Metal/Alloy as such.

Regards Per-Ove

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