The solid metal in the solution is not required. It just extends the life of the solution. I bought a 1 pound roll of tin/antimony solder when I truly started refining about ten years ago and still have about a half roll left. You should always have HCl, and you should always have tin metal. That way you can have fresh stannous chloride in a couple of hours any time you need it. You should sacrifice 1 gram of gold as soon as you get 1 gram available. Dissolve 1 gram of refined gold in 1 liter of chloride solution. I would make a bead and beat it flat. Dissolve it in HCl and household bleach. Place the bead in 100 ml's of HCl and add bleach 5 ml's at a time and give it 10 minutes and add some more until the bead is completely dissolved. Boil the solution until all tiny bubbles stop being generated. Put the solution in a container that will hold 1 liter with a screw on cap. Place the solution inside and top it off with distilled water. This is your gold standard. Test your stannous chloride against your gold standard each day you will be using it. If you get a negative on your gold standard, make fresh stannous chloride as what you have has gone bad. Gold standard solution has no expiration date and should last your whole refining career.
It is not required.
All you need is Tin dissolved in HCl.
So I dissolved some 5-10 grams Tin, I really don’t remember,
in full strength HCl.
When it didn’t do anything more I topped the bottle with water, 5ml or so.
There was plenty Tin left so I left it there and it held at least two years.
I have now been absent another two so it will be interesting to see how it will perform when I get back.
So as they say, all roads lead to Rome, or if you prefer,
there is many ways to skin a cat.
It can be done many ways, what you really
need is Tin dissolved in HCl, either by dissolved salts or metal.
How you do it makes no difference.
Just make sure you have a test solution to test it against.