Watch as I make a bottle opener out of an old rusty railroad spike!
The finish that I applied after cleaning the spike off is a pure beeswax. After heating the spike to a straw yellow I applied the beeswax and continued applying heat until the metal turned black.
I tested the finish by putting water on the spike and leaving it overnight. No rust at all, and in actuality the water beaded off immediately.
Full disclosure, I the top tooth of the opener should be at a more aggressive hook, While this does work it is a little slippery.