I do a water rinse when "necessary" on my one and only meer. The material will quickly soak up water, just be sure to let it dry for several days before using it again, as you don't want any steam expanding within the material.
Meers need only a wipe with paper towel right after smoking. Remember, the inner bowel will look black from the heat of the smoke, and it will stay black. But the key is to not build up cake. The black (or dark) bowel doesn't effect the smoking qualities at all.
My understanding is that the meerschaum gets soft and vulnerable after the smoke and should be allowed to cool and dry before doing any care. (referring more to inside the bowl)
The reason for wanting to rinse is more for the smudgy handling marks accumulating on the outside.
With the disassembly for cleaning, invariably I end up transferring some ash stains to the outside of the bowl and was hoping it was OK to rinse them a bit.
Cake has not been an issue, so far. In fact, just wiping the outside with a damp cloth would probably address my concerns. I just want to make sure I wouldn't be violating any known care standards.
Our venerated late member fishnbanjo sent me my first Meer, an estate pipe, which I rinsed out under the tap briefly, and cleaned up the bowl and shank with a paper towel and pipe cleaner. I cleaned the stem out with dish detergent and a pipe cleaner. No harm done, smokes great, a keepsake of the great man himself, 'banjo that is.
Prolonged soaking in water can cause the meer to double its weight! Then you'll need several days dry time.
But a quick rinse with hot water will not add appreciable moisture, and you can clean the outside as well as flush the airway (and chamber of course) inside of 30 seconds. Mild dish detergent with a cotton cloth should remove most dirt and markings from the exterior. I've smoke a meer or two right after such a cleaning, but some dry time is a good thing.
Funny, I took the Meer to show my local independent pipe shop owner, and his assistant looked over his shoulder, and when I mentioned I'd rinsed it off, his helper went into a pitch about how wrong that was. I just passed it off, having had some advice on Forums, and I noticed the proprietor didn't echo his helper. So that was pleasing. Knowledge is power. It's good to be conservative about how you treat your pipes, but it get exaggerated quickly.
Quite right, Tom.
Some 50-100 years of a few manufacturers printing out "Don't ever use water on your pipe!!" has caused generations to believe that. Odd those folks would print that, given that if you were afraid of water, you'd buy their patented "pipe cleaner" or sweetener, often alcohol based. Ah, commerce.