How to dilute inks to paint with

This will seem funny at best. I have a lot of inks that are too old to print with, but run a school that could use the inks to paint/create with. I wonder what solvent to use to dilute the inks? Water? Some acrylic medium? Adults would use the inks, not kids, and would wear gloves and the like. But these are so rich it would be a shame to dump them when there are so many ways we could use them.

Distilled water should work just fine. Shake the inks before use if they are kept on a counter for long periods.