Waterproofing but not wood.

I thought that you people could help me out, or give me some ideas.

What I would like to do is waterproof a custom made metal coin. I use galvanized steel and paint it with an epoxy acrylic paint. Then place a custom logo I made on the computer printed on a clear label. I then tried spraying it with Krylon Triple Thick clear glaze. The coin looks great but I have found out that when it gets wet or damp the clear glaze deteriates and then the logos ink smears. I'm looking for a coating which has a good possiblity of getting damp that can hold up better then what I originally tried.
Any ideas? A spray would be best.
Thanks.

Have you thought about encasing it in casting resin? then machining it back to a thickness that will still protect the coin without making it seem so bulky?

What about etching the logo on the coin instead, google it bound to turn up plenty!