Base metals test with stannous chloride

[sayf]

Hello everyone,
C M hoke says that the stannous test gives no result for the base metals such as iron or copper

but am sure that iron and copper gave me a false positive when i tested them separately

i dissolved a piece of iron in aqua regia and did the same for a piece of copper
the stannous test for the AR containing copper was a temporary brown color

the stannous test for the AR containing iron was a temporary deep black color

am i mistaken guys??

 

[Torpedo Tech]

I have seen that same result for FE & Cu, also yellow result for Pt. I wouldn't rely on it to heavily.

 

[Lino1406]

When it is temporary - no PM. With high concentration copper does precipitate with stannous

 

[MicheleM]

Hello everyone, I have the same question, I did a stannous test and obtained this:

Because i m not expecting Palladium, it could be copper contamination?

 

[nickvc]

Stannous is very sensitive but learning to read what it shows takes some experience , it’s advised to have small quantities of known value bearing solutions at varying strengths to compare what the test is showing until you have a full understanding of the test results.

 

[MicheleM]

Yes you're right, Au is easy to spot, but I have no experience with Pd and no sample solutions. I have tested a couple of contacts taken from Reed relays that should have Ir/Rh/W plating (according to literature that I found). 2 days in HCl , 2 days in HCl + 3 % H2O2 (50:50) to remove base metals (No positive to stannous test)and then HCl-Cl with the brown/green result shown in the picture above, but I still have some undissolved foils (that should be Ir or Rh ) so I'm not expecting Pd at all

 

[kurtak]

am i mistaken guys??

No you are not mistaking - there are all kinds of things that will give a false positive

That is why it is important to get samples of the metals you are testing for (Au/Pd/Pt) - even if you have to go buy a gram or two of those metals & then do the stannous acquaintance tests as described in Hokes

once you are acquainted with the results of a stannous test on those pure metals you will never again mistake a true positive from a false positive --- that is with one exception - that exception is testing for Pt

IF (the big if) you have molybdenum in solution it will give you a false positive for Pt that looks very much like Pt

you can read about that here -------

https://goldrefiningforum.com/threads/stannous-test-result-platinum.25126/#p266162
if you read what I posted in that thread it tells you how to test for Mo

Hello everyone, I have the same question, I did a stannous test and obtained this:
View attachment 48530
Because i m not expecting Palladium, it could be copper contamination?

Those are clearly false positives

There is a ton of info about false positive here on the forum

Here are some links to threads where there are detailed discussions about false positives --- though these threads are about things other then stannous testing - stannous testing & false positives are discussed in detail as well --- so you will have to go through the threads to find the info on stannous testing

https://goldrefiningforum.com/threads/ka-drivers-videos-where-may-i-find-them.29615/#post-314186
https://goldrefiningforum.com/threads/palladium-precipitation.29787/
https://goldrefiningforum.com/threads/sodium-chlorate-palladium-process.29659/
https://goldrefiningforum.com/threads/cement.29596/
https://goldrefiningforum.com/threads/here-is-one-for-the-experts-here.26651/
https://goldrefiningforum.com/threads/stannous-test-result-platinum.25126/#p266162
Kurt

 

[MicheleM]

Thank you very much @kurtak I am going to read all of them

 

[Liquidau]

Gents, I used AR on some IC memory flatpaks (471) and was processing some fingers (481). The Stannous test images are attached. Can anyone read what 471 shows? Thanks!