Could anyone help me identify this machine?

[jimbalaiya]

Could anyone help me identify this machine?

http://www.youtube.com/watch?v=3ZYaTHbO-0k

I am looking for the model , app. price ( I wonder if this is less expensive than the hald held gun type), and if this machine is capable of analyzing gold flakes and gold dust

I looked for this machine on spectro.com but no luck.

Any response is greatly appreciated :lol:

 

[rusty]

Could anyone help me identify this machine?

http://www.youtube.com/watch?v=3ZYaTHbO-0k

I am looking for the model , app. price ( I wonder if this is less expensive than the hald held gun type), and if this machine is capable of analyzing gold flakes and gold dust

I looked for this machine on spectro.com but no luck.

Any response is greatly appreciated :lol:

http://www.spectro.com/pages/e/index.htm

 

[goldsilverpro]

A comment about the touchstone the guy used.

What that guy on the video and most everyone else don't seem to realize is that the touchstone test is a "comparison" test and not a test where just using the acids alone automatically tell you what you have. The way to correctly use the touchstone is to compare the reaction, the reaction time, and the reaction colors to samples of karat golds with known karat compositions. You make streaks side-by-side of the standards next to the unknowns, apply the acids to all, and then immediately observe and compare, for about 10 seconds, or so. The more standards you have, the more accurately you can narrow in on the true karat of the unknowns. I read an article about the British Assay office that said they could use the touchstone with an accuracy of 1/4K - about 1%. They must have had a ton of different standards. I don't know what they presently use there, but I wouldn't be surprised if they still use a touchstone.

Please note that you can't buy, for example, 13K or 15.5K acids. The standard 10K, 14K, and 18K acids will work for all the karats in between, as long as you have standard karat golds to compare.

The 14K, and higher, acids are some form of aqua regia and they will slowly lose their strength over time. They can also get contaminated. Therefore, the reaction on, say, 14K yellow, will change over time. However, by comparing the sample against standards, this change will occur on both, equally.

After spending a lot of time with the touchstone, since they have developed a good feeling for the reaction times and the colors produced, a person might dispense with the standards. However, standards should still be used often to check if anything has changed. A place I once worked for bought and liquidated an old pawn shop that had 1000s of rings and other items which had to sorted by karat. I soon was able to sort them with decent accuracy while occasionally using standards.

When buying, I prefer the touchstone, any day.

It was interesting that the x-ray came up exactly 14K on both pieces. Why not 13.8 or 13.3, both of which being much more likely?

 

[4metals]

I agree with GSP, you can get very good with a stone. This guy is pushing fast and reliable, if it says 14K he will pay on .56 just so he is covered. He downplays the stone because he spent over 30K on an XRF

Most of the guys that I know who test on the stone use nitric acid, they do not use the mixed 10 14 or 18 blends. They do however use test needles routinely. Today if you buy a test kit it comes with no needles to use as standards, if you're serious about stone testing you should invest in the test needles. If you save dip tube samples from melts and match them up with fire assays, you can use them for standards.

 

[goldsilverpro]

A long time ago, a guy I knew used only nitric at first and observed it for awhile. Then he added a tiny drop of HCl (I think - he may have used some other chloride solution) and watched that for awhile. He claimed this was the best way. He was amazingly close to fire assays. I wish I had watched more carefully. He was pretty secretive.

In the Gold Bulletin, there was an article where they used CuCl2, instead of HCl, mixed with HNO3. Another article I have somewhere used a white stone and different mixes.

I must admit that the results from the mixed acids can get foggy after they have sat around for awhile.

 

[4metals]

I watch them line up a row of 20 pieces to test, the people who are selling are actually buyers so the goods are sorted by karat already, and make 20 streaks in a row and run a line of nitric acid through the bunch of streaks. Then by looking at the row they quickly pick out anything suspect and test it further. They can test a lot of pieces quickly that way. Believe it or not it can be faster than the machine assay.

It is an art though and the more samples you run, and how frequently you do the testing can make a well practiced touchstone tester fast and accurate.

 

[goldsilverpro]

I watch them line up a row of 20 pieces to test, the people who are selling are actually buyers so the goods are sorted by karat already, and make 20 streaks in a row and run a line of nitric acid through the bunch of streaks. Then by looking at the row they quickly pick out anything suspect and test it further. They can test a lot of pieces quickly that way. Believe it or not it can be faster than the machine assay.

That's exactly the way I did it when I was checking those 1000s of rings at that pawn shop, except I was using fresh bottled acid mixes. I had an 8" stone and also ran about 20 at a time. Goes fast and you don't have to wait 10 (or 30) sec for each ring for the x-ray to compute.

I'm going to try the nitric only. I would think it would go slower on the stuff above 10K and enable you to catch every change. Like in slow motion.

 

[4metals]

The concept is that the nitric will react with everything but the gold, the higher the karat, the more encapsulated the base metals are and the longer it will take a 18 k piece to react vs a 14 k piece.

If you line up a 10 k streak, a 14 k streak and an 18 k streak and run a line of nitric through all 3 you can see the progression.

 

[4metals]

In the Gold Bulletin, there was an article where they used CuCl2, instead of HCl, mixed with HNO3.

That was in a 1981 Gold Bulletin (4) an article called "Touching Precious Metals" I had posted a copy of the article on the forum, I'll have to find it and post it again. This article mentions the accuracy of 10 to 20 parts per thousand is possible, or 1 to 2%.

Interestingly he mentions the difficulty encountered with white gold and the touchstone. Ironically I know of a few buyers who have been beat on the white gold by castings which indicated a higher karat due to the presence of excessive nickel.

 

[jimdoc]

That was in a 1981 Gold Bulletin (4) an article called "Touching Precious Metals" I had posted a copy of the article on the forum, I'll have to find it and post it again.

Ralph has it on Scribd;
http://www.scribd.com/doc/29496340/Touching-Precious-Metals-Testing

Jim

 

[jimbalaiya]

Thanks everyone for the input.

So from the feedbacks, ... acid testing is still preferred over the XFR machines to test the purity of gold flakes and gold dusts...?

:lol:

 

[qst42know]

I would like to see what his machine showed on a US bullion coin.

I added his results.

40.87 base metals for the bangle.

42.2 base metals for the earrings.

A bit off from the start.

As a surface read device wouldn't you need a cleaned item and gloves to get an accurate result?

 

[jessica]

Thanks everyone for the input.

So from the feedbacks, ... acid testing is still preferred over the XFR machines to test the purity of gold flakes and gold dusts...?

but i think XRF machine is much better, for it is less complicted, more stable and you just need several minutes to get the results.

 

[philddreamer]

GSP wrote:
"It was interesting that the x-ray came up exactly 14K on both pieces. Why not 13.8 or 13.3, both of which being much more likely?"

That was the first thing that caught my attention. Why not show the % of gold. too? From my expirience, most sellers don't have a clue of how to figure the % of gold in the items & those that can't, end up getting paid much less.
On the other hand, the sellers that do know, will expect to get paid for full 14k as the machine states. I have a Mizar24, but I don't use it as I used to, because it rounds to the next highest 2k; & when I refined @ home, I found I was short & lost in the transaction. After that expiriece, I bought some items stamped 14k; well the Mizar24 read 12k, the touchstone test proved even less. I paid for 11k. After refining it was a bit over 11k.
Touchstone is what I use & rely on; I don't need such an expensive device @ this point, maybe some day, but not today!

Thanks gentlemen for sharing your expertice!

Phil