Partial OT: Cleaning sharpening stones

I needed to put a better edge on some of my tools and was ready to go out and buy some stones. The wife mentioned there were a couple laying about in a closet. I looked and indeed there was a coarse and a hard Arkansas stone. Both were rather crudded up and rather slick. Now I have read recently that the crud is most likely a combination of old oil and metal shavings. Thinking back even further, I recall that for a time I was using water rather than oil as a lubricant. In that recently-read article was written that boiling the stones for 15 or 20 minutes and allowing to cool will soften up the old oil and crud and allow it to be removed. Are there any methods used here that are tried and true to clean up old stones? Note that both are flat and really don't need flattening. Thanks,