Someone was about throw away an old Swedish knife because it was rusty, but our friend the Tinker rescued it. He gave it to me. It certainly was rusty:
.

I decided to use electrolysis to remove the rust. So I set up the zap tank:

I did this on the back porch because the process emits Hydrogen, and I did not want to re-enact the last flight of the Hindenburg at this time :-)>

Two and a half hours later the rust was gone:

I will use some steel wool and oil to clean it up some more. Then I will refinish the handle, sharpen the blade, and make a sheath.