Fun with Copper

Copper is my current obsession, probably because it is beautiful to look at, easy to work with, and relatively inexpensive. Just recently I learned how to solder several flat pieces together. It's like making a peanut butter and bananna sandwich, except that the flame is the knife. What a cool feeling when the two pieces of metal "squish" together as the solder flows, very similar to smashing the bananna into the bread!
The thing about copper is that it likes to change from copper color to green. It's ony natural. I like bright copper, for jewerly at least. So I have searched and read about how to seal copper, to prevent it from doing the natural thing. So far all of the techniques that I have read about either chip off (like nail polish) or slightly change the appearance of the fihished copper.
If you have any suggestions I'd love to read about them!!