# Stannous false positive?



## takenbyvultures (Aug 16, 2012)

I've done 4 batches and every time I do the stannous test, i get this same color. Is this a false positive or bad stannous? I purchased the stannous in 1/2oz vial from ebay seller sparky112 and keep it in a cool dark place.


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## jimdoc (Aug 16, 2012)

Do you have a known good standard to test the stannous with?
That is just as important as having stannous.

Jim


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## takenbyvultures (Aug 16, 2012)

I have some gold powder precipitating right now and just took a light sweep of the bottom of the glassware so there is a small amount of actual powder on the swab, I added a few drops of stannous and got the same color (?)


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## jimdoc (Aug 16, 2012)

Stannous only tests for metals in solution, it won't work right with powders, unless you get them into solution first.

Jim


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## takenbyvultures (Aug 16, 2012)

The solution should be stronger or more concentrated at the bottom right? So if i took sample from the bottom where the powder would be settling, it should give the best reaction with stannous? I've never gotten a purple, orange, green, or anything that I've seen in photos indicating other metals either, only this one rusty color, this leads me to believe the stannous is bad.


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## jimdoc (Aug 16, 2012)

I would put everything on hold until you figure out what is going on, or get some other stannous.
It does go bad after a few weeks. It is always best to make it fresh when you plan on needing it, and test it first, so you know you can trust it.

Jim


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## takenbyvultures (Aug 16, 2012)

I've never made it before, are these instructions correct? Do you recommend a certain place to purchase tin powder from?

*Place 2 grams of pure Tin powder in an eye dropper bottle and Dissolve it with 30 ml of hydrochloric acid 32 % (HCL). You can give it a short boil to get the reaction going or just let it react at room temperature, when stop fizzing & bubble and cooled down your stannous chloride test solution is ready to use.*


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## jimdoc (Aug 16, 2012)

takenbyvultures said:


> I've never made it before, are these instructions correct? Do you recommend a certain place to purchase tin powder from?
> 
> *Place 2 grams of pure Tin powder in an eye dropper bottle and Dissolve it with 30 ml of hydrochloric acid 32 % (HCL). You can give it a short boil to get the reaction going or just let it react at room temperature, when stop fizzing & bubble and cooled down your stannous chloride test solution is ready to use.*



That should work, or this from Hoke's book;

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=48&t=2082&p=17541&hilit=stannous#p17541

I think Lazer Steve sells tin on his website.

Jim


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## takenbyvultures (Aug 16, 2012)

Thank you for the info, I remember seeing a video where pieces of solid tin are dropped in to make stannous, can solder be used or is there too much lead in it?


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## jimdoc (Aug 16, 2012)

takenbyvultures said:


> Thank you for the info, I remember seeing a video where pieces of solid tin are dropped in to make stannous, can solder be used or is there too much lead in it?



Look for lead free solder that is at least 95% tin, the rest should be antimony and should settle to the bottom of your container. The tin in the solution helps it to stay fresh.

Jim


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## takenbyvultures (Aug 16, 2012)

Thank you very much jim, my name is Jim also, maybe we can overtake the numerous Steves on the forum :lol:


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## jimdoc (Aug 16, 2012)

takenbyvultures said:


> Thank you very much jim, my name is Jim also, maybe we can overtake the numerous Steves on the forum :lol:



I think there are probably just as many Jims as Steves if you check.

Jim


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## lazersteve (Aug 16, 2012)

Just so happens one of my brothers is named Jim (and one Joe, and one Mike).

Steve


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## Palladium (Aug 16, 2012)

takenbyvultures said:


> The solution should be stronger or more concentrated at the bottom right? So if i took sample from the bottom where the powder would be settling, it should give the best reaction with stannous? I've never gotten a purple, orange, green, or anything that I've seen in photos indicating other metals either, only this one rusty color, this leads me to believe the stannous is bad.




It will not test for metals once they have been precipitated. Think of this. In order for you to have gold precipitate then your free oxidizer must be used up. Other wise you would have no gold on the bottom. Two if you have done it right the gold will drop completely from solution because the free oxidizer is gone and the smb can produce gas which saturates the solution and causes your gold to drop. If you had free oxidizer then so2 would be consumed because of this and no gold would drop. So what you are seeing as brown is a false positive from the reaction of a solution that has free so2 gas that is reacting with your stannous chloride to produce the brown stain. Had gold been there and it turned purple then this would have told you the excess so2 was gone and you need to add more smb to produce more gas to drop your gold. Stannous chloride tests for gold ions. You have metallic gold which has been reduced to a metal in the solution and will not react with stannous cholride. Did you test it before the drop of your gold to see if it tested positive? This would have told you if your stannous worked or not.


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