I know how you feel about blast white coins. The exception to blast white is when wear is obvious. This coin is great for blast white, but I think the future is not good.
I've heard to get old copper pennies and put them in. Some people do that with their safe deposit boxes in the bank.
Use Zincolns. Their copper surface is even more pure than a "copper" cent, and if the zinc gets exposed, it's a LOT more reactive even than the copper. Plus, you're getting rid of Zincolns, which is always good.
I have found that dipped coins will develop a secondary toning much quicker than mostly white coins with an original skin, which is one of the reasons I am not a "blast white" guy.