Touchstone Assay Precautions

[Anonymous]

If I'm going to be performing touchstone acid tests of gold jewelry with Nitric Acid and Aqua Regia, what safety precautions do you recommend I take? Especially with regards to acid vapors? I know the 3M masks are recommended for refining operations, but are they also necessary for testing? I really enjoy working lungs, so thanks in advance for any advice.

 

[leavemealone]

If I'm going to be performing touchstone acid tests of gold jewelry with Nitric Acid and Aqua Regia

Am I reading this correct?Are you going to be testing gold using aqua regia?

 

[Anonymous]

Yes, but only using Aqua Regia for high karat pieces (22k+) with a scratch stone.

 

[Barren Realms 007]

Yes, but only using Aqua Regia for high karat pieces (22k+) with a scratch stone.

Why are you wanting to disolve your gold? This is what you are going to do with the AR. And what test will you use to tell when the AR is used up? It starts reacting when you mix the chemical together.

 

[Harold_V]

Yes, but only using Aqua Regia for high karat pieces (22k+) with a scratch stone.

Why are you wanting to disolve your gold? This is what you are going to do with the AR. And what test will you use to tell when the AR is used up? It starts reacting when you mix the chemical together.

That is the accepted method of testing with a touch stone. It would benefit both you and Johnny to do some research in that regard, so you'll understand what kingmolson is talking about.

Tests on a touch stone are generally accomplished by comparing a streak against a known standard of gold fineness. Touch stones and test needles are a part of a kit, as are three different solutions, one of which is AR.

Harold

 

[Barren Realms 007]

Yes, but only using Aqua Regia for high karat pieces (22k+) with a scratch stone.

Why are you wanting to disolve your gold? This is what you are going to do with the AR. And what test will you use to tell when the AR is used up? It starts reacting when you mix the chemical together.

That is the accepted method of testing with a touch stone. It would benefit both you and Johnny to do some research in that regard, so you'll understand what kingmolson is talking about.

Tests on a touch stone are generally accomplished by comparing a streak against a known standard of gold fineness. Touch stones and test needles are a part of a kit, as are three different solutions, one of which is AR.

Harold

Thank you I will do that.

 

[Anonymous]

Harold, thanks for the clarification assist. Do you have any advice on the acid vapors?

 

[Harold_V]

Certainly I advise against breathing them, but you will be working with just tiny containers, generally a bottle with a dauber. Fumes shouldn't be an issue, although when you mix your AR there is some gassing. I suggest you have no more than a liquid ounce made up at any one time. It will do hundreds of tests. Just avoid breathing the obvious fumes, and don't get the solutions on your hands. I used test solutions, including concentrated nitric, for years with no problem, aside from some very yellow burned skin on occasion. Make sure you wear rubber gloves. My favorites were a blue glove with yellow cuffs. Flocked inside, they cost about $2.00/pair, and lasted about three weeks before a hole would spring in the left ring finger. Same place every time! I wore these gloves for several hours daily, often more than ten. They were the best glove I ever encountered. Thin enough to retain some sense of feel, and easy to get on and off. I used corn starch inside once the flocking wore out.

Harold

 

[goldsilverpro]

I think you'll find that the 10K acid is usually the only one made up of just nitric and distilled water. The 14, 18, and 22K acid are varying strengths of aqua regia.. I posted the makeups of these a long time ago. I also think they're on the Shor site.

 

[Barren Realms 007]

I think you'll find that the 10K acid is usually the only one made up of just nitric and distilled water. The 14, 18, and 22K acid are varying strengths of aqua regia.. I posted the makeups of these a long time ago. I also think they're on the Shor site.

This is not something I have read up on, But I am guessing that when you rub the item on the stone that the test liquid is disolving the gold on the stone and that is determing what karat it is.

 

[goldsilverpro]

Barren Realms,

Download and read the Pawnbroker's Guide from the 1st post in this thread. It is one of the best info sources for using the touchstone.
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=54&t=3624&p=30753&hilit=pawnbroker+bob%27s#p30753

 

[Barren Realms 007]

Excellent thank you sir.

 

[goldsilverpro]

Here's an old thread on the acids.
http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=39&t=311&hilit=touchstone+acids

Also, an interesting article in the attachment, using a little different approach

 

[Anonymous]

Thanks for the information, I really appreciate it.

 

[Barren Realms 007]

Thanks for the information, I really appreciate it.

Sorry for steering you worong on the start of this thread.

 

[61 silverman]

this may be a bit late too help but here is a picture of a touch stone in use..