Contact Plating is a very simple way of coating noble metals with lesser noble or even reactive metals, in this case Copper is more noble than Tin, people usually coat copper with Tin using electric current or very nasty chemicals, but with cotact plating all you need to do is to make the copper piece come in contact with a metal more reactive than Tin, in this case aluminum, the electrolyte is a simple Tin Chloride(SnCl2) in water, I wanted to use copper pennies but I had a hard time sourcing them from my local banks, so I used the copper plated quarters that I coated earlier on my other instructables(copper plating a quarter without electricity).
on the to pic(copper plated quarter, Tin plated quarter and normal quarter).
Step 1: Materials.
Gerber baby food container and lid.
Stannous Chloride(SnCl2, 10 grams per 100ml)
Safety glassess and latex gloves.
Step 2: Coating Copper With Tin
Mix the 10 gme of SnCl2 with 50 ml of water, then pour the rest, wrap the inside of the container lid with a thick aluminum foil cover(dont make it too thin as the foil will desolve too fast to act as a negative contact), pour enough electrolyte to cover the copper piece, turn the piece from time to time to make an even coat of tin, the coat will be a dull whitish coat but it shines very easily and is very strong, this process can be used to coat Copper PCB with Tin using the same principles.