I have a piece of Emery Cloth - far better than sandpaper tucked in my double Pot call Pouch on my vest....it has to be at least 10 yrs old...Emery cloth stands up to moisture far better than sand paper. Also condition the pot call (sand or stone) in one direction only!
For Pot call care we have a FAQ section written by a longtim HNI contributor.
Link
http://www.huntingnet.com/forum/specific-turkey-tips-tactics/244283-guide-pot-calls.html
I also stitched a piece of green Scotchbrite, to my vest, in a convenient spot, as I use this to touch up the tip of any striker quickly. It helps me if the striker starts to go sour or got damp asI just rub or scour it on the pad quick like.....
Lastly I carry a Bic Lighter to flame the surface of the pot such as slate to help dry it quickly. Or even flame a wooden striker.....
JW