Understanding reactions (gold processing, and Identification)

[upcyclist]

Back on the testing, Schwerter's Solution can also be used for gold-plated materials, as long as it's NOT white gold. Schwerter's turns blue in the presence of nickel, and if it ain't white gold, nickel has no business in that alloy. Nickel is a powerful whitener in alloys (hence the use in white gold), but it's also common in pot metal alloys used in plated jewelry. If the Schwerter's turns blue, and it's not white gold, it's not a gold alloy past the first few microns.

Which makes me think of another random test: if you put a cheap disposable butane torch on it, and it melts into a blob in 15 seconds or so (perhaps with a gold skin), it ain't a gold alloy

More details on Schwerter's reactions (a nice addition to any test kit) can be found in the General Reaction List on this forum.

 

[orvi]

DMG is very very sensitive to nickel, very visual (nice piknish-red colour forms). maybe drop bit of nitric to the contact, let it dissolve a bit from under gold, drop some neutralizer like solution of soda and finally drop of DMG in say ethanol. Ni-DMG complex cant be dropped well from acidic solutions and if there is pH higher than 5 (also could be tested with pH paper), nickel, if present, wont hide
maybe bit complicated, but access to dichromates (now classified as carcinogens=regulations) needed for Schwerter could be limited for somebody.

 

[CattMurry]

Back on the testing, Schwerter's Solution can also be used for gold-plated materials, as long as it's NOT white gold. Schwerter's turns blue in the presence of nickel, and if it ain't white gold, nickel has no business in that alloy. Nickel is a powerful whitener in alloys (hence the use in white gold), but it's also common in pot metal alloys used in plated jewelry. If the Schwerter's turns blue, and it's not white gold, it's not a gold alloy past the first few microns.

Which makes me think of another random test: if you put a cheap disposable butane torch on it, and it melts into a blob in 15 seconds or so (perhaps with a gold skin), it ain't a gold alloy

More details on Schwerter's reactions (a nice addition to any test kit) can be found in the General Reaction List on this forum.

I actually found that the HCL with not even heat will eat any paint trying to fool observations. It will also act like de-plating acid and flake gold away from brass if it is the underlying metal (usually is). It eats the zinc, and really wants to get at it. For my case with the door handle trim/guard it was clearcoat which did get jellified. Thus showing the brass material was painted.

Also, Ni is ferromagnetic for the most part. Wouldn't just using a magnet be suitable if that was present? No clue what is happening to my test.

Also #2, Ni reacts with HCL so again. It will eat zinc in brass, and nickel basically flaking away the Au.

 

[upcyclist]

Also, Ni is ferromagnetic for the most part. Wouldn't just using a magnet be suitable if that was present? No clue what is happening to my test.

Also #2, Ni reacts with HCL so again. It will eat zinc in brass, and nickel basically flaking away the Au.

Nickel is magnetic, but it's not necessarily detectable with a ferromagnet (ye olde style magnets). You might be able to use a ferromagnet to tow a nickel alloy in a paper boat, but that's about it I think. You can definitely detect even a nickel underplate with a neodymium/rare-earth magnet, though it's quite subtle for anything heavier than a plated pin (though float tests can work).