Testing Gold buttons with acids, how long should I let the test go for?

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ImTechMan

Member
Joined
Aug 14, 2017
Messages
13
I have a lot of buttons and no stone, I know I need to invest in a stone at some point but if I scratch the button and drip a drop of test acid on the button, lets just say 10k, how long should I leave the acid on the button with no reaction? a lot of buttons have little or no reaction in the first few minutes-30 minutes, but if I leave it overnight they will develop a small green/blue discoloration around the button.

Is that just the test acid eventually breaking down the base metal? and if so, does that mean its a lower Karat? or that is just going to happen to any impurities in acid over time regardless?

I have read elsewhere that (with testing on a stone anyway) no reaction after 15-30 seconds is good enough, I have also read minutes etc. when testing jewelry for gold plating. I haven't come across anything regarding test time for buttons however and am just looking for some input, Thank you in advance!
 
Depending on the test and what you are looking for, sometimes the acid drop will go onto the scratched metal (ring, chain...) like when checking for plating, or for silver... but normally to check the karat of the gold, the acid drop goes onto the scratch mark made on the stone by the ring, the scratch mark dissolved in a certain concentration of acid, or the acid did not attack the scratch mark...

Like Jimdock said even the bottom of a coffee cup can act as a stone.
with the stone, the reaction of the acid is very quick, maybe not instant in chemical time, but almost instant in our time.

Putting the acid on a scratch onto the gold button, to test gold buttons (for karat) would not work well, sitting there forever would not help.

Now testing the scratch made by the gold button on the stone or tile would tell you something. But then again not much really, unless your button had an awful lot of base metals, it could tell you your button is greater than 22K, or maybe better than 90 % gold, but in refining that is just an indicator that your gold still needs to be refined anyway, but heck I can tell that by just looking at the gold button with no pipe, and the color of my melting dish, no need for the acid stone test.

A better test for the buttons without a pipe would be to weigh the buttons, dissolve and refine them twice, and then re-weigh the beautiful gold button with the pipe, to see how much base metals was lost in the process, then gauge the purity of the buttons before refining with the math.
 
You compare the scratch made onto a stone (or similar) of the button of unknown karat against the scratch from a button of known karat. When you use the acid test, a drop on each scratch (made on a stone) is used to see how one dissolves compared to the other scratch. You keep comparing the scratch of a known karat piece to the unknown piece until you find that the acid dissolves both about the same, then you know the karat of the unknown button is approximately that of the known karat button. Note that you may need a range of known karat buttons (10k, 14k, 18k, 22k, etc.). These reactions are fairly fast, less than 20 seconds, but can vary based on acid concentration, acid makeup, temperature, etc. As you get experienced, you will be able to quickly know the approximate karat value based on how fast the scratch reacts.
 
I sure missed a lot while I wasn't here these last few months.

I couldn't seem to find this in the "books" section (I swear it's in there somewhere), so I'm re-uploading it for others, incase they need more information also.
 

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