# Various methods for making stannous chloride



## 4metals (Apr 27, 2018)

This is a thread we are starting, by request, to get all of the formulations into 1 place for making this necessary refining tool. Stannous chloride is the eyes of the refiner, it indicates the presence of values out eyes cannot see and it does so on a real time basis so the test is definitive and quick.

If you can just purchase the reagents required, I prefer this formula;

Stannous chloride test solution

2 grams stannous chloride crystals. 

1 gram of tin metal. 

40 ml of water

5 ml Hydrochloric Acid

Both of these chemicals are available from Carolina Biological Supply. These are the best prices I have found to date, and they seem to blow away the pricing of Action Mining. 

https://www.carolina.com/specialty-...de-100-g/892380.pr?question=stannous+chloride

https://www.carolina.com/specialty-...atory-grade-25-g/896304.pr?question=tin+metal

And now I invite the other formulations used by members.


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## Shark (Apr 27, 2018)

I use two tin sinkers, 30ml of water and 10ml of hydrochloric acid. I then run very hot tap water around the sides of the bottle until I can see a reaction starting to take place around the sinker. I then sit it aside, usually in an area where sunlight can get to it for warmth. I normally start using it within 10 to 15 minutes. The sinkers I use are made from tin, (the eco friendly type) they are 3/8 inch in diameter and weigh 3 grams each. (sorry I don't recall the size and just grab them by eyeball view. 

I do substitute a 96% tin 4% antimony solder at times. I still use the the 6gram weight and every thing else the same. If I don't have access to hot tap water, I heat a glass of water on a coffee maker and dip the stannous bottle in and out of the water until I see the reaction start up.


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## g_axelsson (Apr 27, 2018)

I have a beaten up pewter bowl I bought soon after joining the forum. I spent about a dollar and with this rate it will last me a lifetime. The stannous usually goes bad before I run out of it.

Swedish pewter or tin objects usually is 97-99% tin and 1-3% antimony... I think. When the tin dissolves it leaves some black residue behind. I usually decant the liquid and discard any solids.

What I do when I start a new batch is to cut a few grams of tin metal in cm-sized pieces and put it into a beaker. I then add around 5-10 ml of hydrochloric acid and put it away in a safe spot. Then I check it daily to see if I have too little tin or if the reaction have stopped. (No more hydrogen bubbles forming.) If the metal is all dissolved then I probably have an excess of HCl so I just add a few more strips. The goal is to have some metal left when the reaction dies down.
When the reaction is finisher and there is still some metals left I decant the clear liquid and put it into a dropper bottle.

As I do this outside I add a dust cover as it usually takes a few days when running it cold.

The stannous chloride is tested against a gold standard at first when I make it, and then daily every time I need to use it.
... actually I'm cheating there. I only test the stannous if I get a negative result in the first test, a positive test is also a test of the stannous chloride.  

For storage the most important rule is to keep it in an air tight vessel, then it can easily last for months or even years.

Göran


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## g_axelsson (Apr 28, 2018)

Some links to previous discussions :

* GRF : Making stannous chloride
* GRF : Stannous chloride formula and test results
* GRF : Testing for rhodium
* GRF : False positive with iodine
* Wikipedia : Tin(II) chloride
* Hoke : Stannous chloride testing solution, for all precious metals
* ScienceMadness : Tin chemistry summary (pdf)

And some videos :
* Video of testing with and making stannous chloride
* Making stannous chloride from solder

/Göran


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## snoman701 (May 2, 2018)

I use 95/5 solder. I cut up a bunch at a time...usually ten lots worth. 

I have Boston round dropper bottles that I put the pre-weighed tin in, so that all I have to do is add liquid and wait. When I add liquid, I date it. Two weeks later I throw it out and make a new one. 

At 50 cents for a dropper bottle, it would only take one false negative to pay for a lifetime of always fresh test solution. 


Sent from my iPhone using Tapatalk


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## 4metals (May 2, 2018)

The only time I have noticed the stannous chloride I have made go bad is when it sits for a few months in a bottle that is almost empty and has a lot of air in the bottle. But in an active shop using it every day it is usually used up quickly enough that it doesn't go bad. 

BUT, whenever I get a negative result the first time using the stannous on any given day, I always test the stannous chloride on a solution of aqua regia I know has gold dissolved in it. In an active shop there is always a solution sitting around that you know should test positive but if not I always have on hand a solution in a dropper bottle made by digesting a fraction of a gram of gold sponge in a small quantity of aqua regia and diluting it to fill a small (50ml) dropper bottle.


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## g_axelsson (May 3, 2018)

About storing stannous chloride solution.

When I started refining gold 10 years ago I made stannous chloride by just dissolving a couple of pieces of tin in HCl, adding more until no more dissolved. It worked great and I kept it in a small beaker with some saran wrap over the top. I used a pipette with a small rubber bulb to pull stannous solution for testing. The solution worked perfectly for a month before going bad.

Later I did a batch but never wrapped the top in saran wrap... that batch went bad in just a week, teaching me a valuable lesson about stannous chloride and oxygen.

Now I'm making my stannous in the same way but I store it in a small dropper flask with a rubber seal, no excess oxygen gets into it. Last time I made a batch was over a year ago and it is working just fine, just tested it.

Easiest way to see that stannous has gone bad is to look for a white precipitate in the storage bottle, it usually starts to show (according to my experience) when stannous chloride might still work but the reaction is weaker than when freshly made.

And of course, most reliable way to see if stannous chloride has gone bad is to use a test solution of known (or at least consistent) strength so you can compare it to the reaction in previous runs, then you know when the reaction is weaker and the stannous is starting to go bad.
The test solution I have is made from a few drops of pregnant gold chloride solution and diluted to the point where it only shows a pale yellow tone. If I would guess I would say at a level of around 1/10 of a gram per liter.

Göran


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