Hi, I am aware is not recommended to clean the old coins, but most if the coins in my collection have been poorly stored and handled so far, and I'd like to rinse them to remove the fingerprint/sweat traces. What would you recommend to do in this case. I'm not interesting in scrubbing any dirt or to change the surface in any way. But I understood in time the fingerprints and sweat can damage the surface. Any advice? I also imagine there might be different substances to use depending on the material each coin is made of. I would appreciate any opinion or guidance in this matter. Many thanks!