Primos brand chalk is what I use
#1 rule keep in dry place ....ziplock bag if your in the swamp, in a vest or bag I often times use a NYLON sock to keep in snug ...nylon doesn't absorb moisture
#2 here is the BIG ONE...never ever leave a push pin call in a hot car....NEVER ...the heat will cause the resin in the wood to "migrate " the glue will do bad things and joints and lamination will buckle , shift, seperate ...you get the drift
In fact ...never pun ANY Turkey call in a hot car ,diaphram , pot box ...it ruins calls more than anything ,IMO the main culprit for most calls going sour on a hunter is a hot car
Back to chalk , I know some folks use railroad chalk for the calls they make ...that works for you keep doing it, I like the primos chalk , couple swipes and it will last many many hunts ....it doesnt clog up the pores in the wood , like other types of chalks that have a wax binder in them
Chalk has away of absorbing moisture and pulling it off the call surface of the call and replacing it with new chalk being rubbed off ....adding bite or grip to the friction surface , if your call sounds slick rub just a LITTLE bit on and your good to go , I even use chalk on aluminum pot calls too......
Always keep your DRY chalk in a small ziplock bag , if you leave it in your vest pocket (loose / no bag)then the chalk will absorb moisture out of the air , and when you go to rub it on your call , you will be rubbing humid or slightly damp chalk on your call and it will take up the pores in the wood
Best way to dry out damp/hunid chalk is to........leave on your hot car dash...lol.the chalk ...not the call
Shannon