I have had some experience with dice.

The ones that smell like vinegar...DEFINITELY isolate them from any other dice. They're on their way out and I'm not aware of any way to save them.

The ones that are crystallizing...if there's no smell, you might be able to stop them from totally decomposing with a coat of clear laquer. The late Jeff "the Diceman" Laudeman recommended using clear nail polish on them. CAREFULLY dab the polish on the logo side, or you might smear the logo. Just do one side, then let it dry really well before doing another side.

I once tried using the nail polish trick on some that smelled like vinegar, just to see if it would help, and all it did was make them sticky.

Here are some examples of why we don't really collect dice anymore .