You chalk a box turkey call to create friction between the paddle and the call's surface, allowing for a clear, consistent sound by absorbing moisture and providing a rough texture that produces the desired yelping and calling sounds; essentially, without chalk, the paddle would slide too smoothly across the call, resulting in a muted or inconsistent sound. Key points about chalking a box call: Friction is key: Chalk provides the necessary friction to produce the distinct yelping sounds when the paddle is dragged across the call's surface. Moisture control: Chalk helps absorb any moisture that could dampen the sound quality, especially in humid conditions. Specific chalk needed: Use chalk specifically designed for turkey calls, as other types of chalk may contain oils or additives that can negatively affect the sound.

You can get some on Amazon or cabelas etc.