We had a plastic box with a plastic grid insert. We put the aluminum foil at the bottom, the grid on top of it to separate it from the silver, and added hot salt water. The cutlery needs to be moved around occasionally so every surface is treated evenly (and the water moves around).

Can confirm the sulphury smell, I usually did this out on the balcony.

And: the aluminum foil partially dissolves during this procedure, it looks like the moths got to it afterwards.