source of tin?

[Scott2357]

Ha ha, looks like Steve was finishing his post will I was fixing breakfast in the middle of mine.

 

[Irons]

I've never made it with solder, but the way I make stannous is to simply combine 1 gram of tin with 30 mL of ~31% HCl, heat until it begins fizzing , be sure to leave some solid tin in the bottom of the container to keep it fresh. After the fizzing stops you can put a top on the solution to keep the air out and store it in a cool dark place.

Follow these advices and your stannous will stay active for several months.

If you feel the test becomes unreliable confirm the stannous chloride is still active by testing a standard gold solution.

Steve

The key point here is keeping the air (Oxygen) away from the solution. Every time you open the bottle, Oxygen gets in and Oxidizes a little of the Stannous to Stannic.

Always store the solution in glass bottle. Polyethylene and many other plastics are permeable to Oxygen.