How long should the stannous chloride test take?

Dr_Code · Oct 11, 2012

I tried to make a stannous chloride test using solder...as I don't have a pure source of tin powder. So I used my solder. That didn't do much in the muriatic acid untill I added (waht I thought was a tin can)

Things started to heat up after that and the solder started to dissolve. After looking at the MSDS for the solder I was using. It is about 60% tin and 40% lead.

To test the stannous chloride, I dissolved a few gold leaf fingers that I got using the muriatic acid/hydrogen peroxide method. I then disolved them using the muriatic acid and bleach method.

It was difficult to determine the test result (I assume because of the lead in the mix...it was always kind of dark/purple)...not clear like it should have been. The darker things seemed to settle out in the bottle. I assume that was the lead from the solder.

I tried a new mix using what I thought was a 'tin can', but I get no reading.

I assume the can I thought was tin is not tin.

This is all very small scale tests - maybe a ml or two of liquid and a few gold foils. I am trying to figure out if my gold solution test is accurate or not.

Should I filter out the lead and use what I get from that?

Is there another source of tin that I could use?

jimdoc · Oct 11, 2012

You should look for lead free solder. It will be 95% tin with some antimony.
The antimony will settle to the bottom as a powder and not have any effects on your testing.

Jim

butcher · Oct 11, 2012

Lead chloride is insoluble in HCl, and the lead in solution of tin chloride probably dragged down some of the violet gold reduced by the tin chloride in your stannous test, lead would be a variable I would not want in my testing solution.

The stannous chloride works the way it does because the tin chloride reduces gold chloride in solution as a colloidal elemental gold metal in solution with the tin solution, this colloidal gold does not settle and the gold suspended in solution looks violet as it reflects light, if the gold settled we would not see the positive in the test like we do.

Tin cans are steel some older cans had a very fine plating of tin to keep the food from dissolving iron, so you actually had a solution of iron chloride not stannous chloride.

95% tin solder is what you want, this is usually easily found now a days as they are trying to limit the lead in solders, some types of fishing weights are made from tin also.

When dealing with chemistry the less variables added the better, and with testing for such valuable metals where a mistake in results can end up costing you a lot of money or gold, why experiment with loosing your gold by adding other variables or trying something other than known working procedures, get some tin (95% solder or pure tin) and study making and using stannous chloride, and follow known working procedures, when learning you will be making enough mistakes, but you will make less mistakes and learn to recover and refine gold easier by studying following the procedures to the letter, and this can keep you from loosing most of your gold while learning.

cnbarr · Oct 11, 2012

Dr_Code said:
I tried to make a stannous chloride test using solder...as I don't have a pure source of tin powder. So I used my solder. That didn't do much in the muriatic acid untill I added (waht I thought was a tin can)

I see a few things wrong here,
1. Most modern "tin" cans are aluminum, that should definitely be keep out of your stannous solution, as well as lead. Go to your local hardware store and find a solder that is 95% tin 5% antimony, it will make a good stannous test solution.

Dr_Code said:
It was difficult to determine the test result (I assume because of the lead in the mix...it was always kind of dark/purple)...not clear like it should have been. The darker things seemed to settle out in the bottle. I assume that was the lead from the solder.

2. A purple to dark purple almost black is a positive stannous test result for gold, a clear test result is a negative or an indication of a bad stannous test solution.

3. Have you download and starting reading hoke, if not please do so, the link is found in many members signature lines? It is the holy grail of the forum, and is must for success.

Good luck,
Chris

Dr_Code · Oct 12, 2012

Thanks for the help.

I do have Hoke's book. I have read it, and am working on a notebook using the book, this site, and my own experiments.

I think the main thing I got from the book is there are many ways to 'chemically skin a cat'. Know the type of scrap you have, so you know how to deal with it. Know what metals are in it, and how to test for them.

Also, don't put all your eggs in one basket, till you know it's a really good basket. Start with small ammounts and learn the process, what happens, and what things should look like.

It's all right there, it's just a puzzle that I need to get all the pices put together.

Dr_Code · Nov 1, 2012

I never did find any lead free solder in any of the hardware stores I stopped at. Yeah, I could have placed an online order, but didn't. Still plucking away at motherboards and the likes while I read more. Today I went to get some lead for a sulfuric cell. I was in the fishing isle, and on the shelf were lead free sinkers, made of tin. Picked up a pack. I'll have to see how they work for the stannous chloride.