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Testing silver, turns black?!?

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Pillar of the Community
Mexico
1277 Posts
 Posted 11/09/2011  11:20 pm Show Profile Bookmark this topic Add harrison2 to your friends list Get a Link to this Message

Since there are a a few chemists and those with experience in testing PMs here on the forum, your input on the results of a test that was performed on some questionable silver would be greatly appreciated .

I brought a marked, reliable piece of sterling along as a "control" and it payed off.

The jeweler use nitric acid and another acid (half a drop of each) to test both the sterling scrap and a recent purchase. The sterling piece turned creamy in color. The questionable piece did not change colors at first. When the acid was wiped away, it left a black carbon-like mark on the white rag and the test spot was left quite dark, almost seemed pitted (was a bit that way to begin with). The white deposit on the sterling wiped right off for the most part, no pitting.

The jeweler stated that the questionable piece was not silver and he had no idea what it was.

That said, I want to ensure that this test actually checks the presence of silver, not some other base metal. One less than reliable source stated that a black result on a nitric acid test for silver means it's coin (90%) silver and white/cream result means it is sterling.

Is this true?

Edited by harrison2
11/09/2011 11:32 pm
Valued Member
United States
286 Posts
 Posted 11/09/2011  11:55 pm  Show Profile Bookmark this reply Add jimineez to your friends list Get a Link to this Reply
my silver test acid turns red with 90%, red with 92.5%, and red with .999 ...
not really an answer to you, but my observation fwiw...
Pillar of the Community
Mexico
1277 Posts
 Posted 11/10/2011  10:47 am  Show Profile Bookmark this reply Add harrison2 to your friends list Get a Link to this Reply
Thanks for the input jimineez!
Pillar of the Community
United States
2024 Posts
 Posted 11/10/2011  11:45 am  Show Profile Check trdhrdr007's eBay Listings Bookmark this reply Add trdhrdr007 to your friends list Get a Link to this Reply
The last silver acid I had also turned red as an indicator. Two things to keep in mind if you use this type of acid. If the acid is old it will not turn as red as quick, & will eventually fail to indicate the presence of silver. A quality(heavy) silver plate will also test red.
Pillar of the Community
Mexico
1277 Posts
 Posted 11/10/2011  12:51 pm  Show Profile Bookmark this reply Add harrison2 to your friends list Get a Link to this Reply
This is what the sterling looked like during the test:

I need to get me some of that red stuff!
Valued Member
United States
58 Posts
 Posted 11/10/2011  1:45 pm  Show Profile Bookmark this reply Add silversam to your friends list Get a Link to this Reply
I use the same method for my silver.

90 to 100% silver, the acid will show a creamy color.
77-90% silver, the acid turns a gray color.
65-75% silver, then the acid will show a light green color
Pillar of the Community
Mexico
1277 Posts
 Posted 11/10/2011  2:01 pm  Show Profile Bookmark this reply Add harrison2 to your friends list Get a Link to this Reply
Thanks silversam! Does this look familiar? It didn't seem to change color at all...until after about five minutes later.



Five minutes later...
Valued Member
United States
58 Posts
 Posted 11/10/2011  2:13 pm  Show Profile Bookmark this reply Add silversam to your friends list Get a Link to this Reply
Yea I believe it's probably coin or 90% silver. as long as the acid isn't a gold color its some sort of silver.
Rest in Peace
United States
9104 Posts
 Posted 11/12/2011  12:04 pm  Show Profile Bookmark this reply Add biggfredd to your friends list Get a Link to this Reply
I thought tests were for the presence of copper. The more copper content, the closer to deep green/black. Pretty sure lead also shows black.
Pillar of the Community
United States
617 Posts
 Posted 11/12/2011  12:57 pm  Show Profile Bookmark this reply Add tokenmast to your friends list Get a Link to this Reply


Still learning about acids. But I think we are talking about 2 different acid testers. one starts out clear, the other orange. The orange one (the one I use) turns different shades of red depending on purity, if no silver is present; then brown or green/blue depending on copper %.
The coin is a force, TFDwall. TrueField Detective . .. Tools and Instruments.cr.tm.pat/pend. Counterfeit/off metal, silver
Pillar of the Community
Mexico
1277 Posts
 Posted 11/12/2011  2:53 pm  Show Profile Bookmark this reply Add harrison2 to your friends list Get a Link to this Reply
Agreed...I have been doing some reading on the matter and I think tokenmast is correct. There are at LEAST two different types of testing liquids...one is orangish and turns shades of red etc...the other is clear (what I was using). I haven't seen any videos of the clear, but have seen some photos of sterling being tested. I'm hoping to go back to get a 90% coin and some other purities tested for comparison purposes.
Pillar of the Community
Mexico
1277 Posts
 Posted 11/24/2011  11:15 pm  Show Profile Bookmark this reply Add harrison2 to your friends list Get a Link to this Reply
Silversam, would you please enable private messages or send me one?
Pillar of the Community
Mexico
1277 Posts
 Posted 12/02/2011  7:30 pm  Show Profile Bookmark this reply Add harrison2 to your friends list Get a Link to this Reply
Well folks, I had to go back and get this piece double-checked, and this time against some know-purity silver items. So, for your viewing pleasure, the test with nitric acid and uric acid. What do you think? Only the 10% Mexican Peso didn't show any sign of cream. Even the 35% nickel showed some cream color.

When wiped, they are showed clear or slightly green for low purity...the item under question: black. Not a good sign.

Valued Member
United States
58 Posts
 Posted 01/22/2012  8:09 pm  Show Profile Bookmark this reply Add silversam to your friends list Get a Link to this Reply
harrison2
Quote:
Silversam, would you please enable private messages or send me one?


Sorry haven't been on in sometime but I'm not sure how to do either?
Pillar of the Community
Mexico
1277 Posts
 Posted 01/29/2012  4:28 pm  Show Profile Bookmark this reply Add harrison2 to your friends list Get a Link to this Reply
Thanks for the follow-up. Was just hoping to compare your results with my own as seen above.
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