I just took delivery of a Cut-N-Paddle by American Friction the other day. It came chalked from the callmaker, Bruce Wurth, who tunes them before sending them out. He had used white chalk so I called him and asked what kind of chalk he recommended. His answer was a large white stick similar to the size of a child' s sidewalk chalk, about 4" long. He said it was called " railroad chalk" or " construction" chalk and could be found in places like hardware stores. He said to stay away from the colored camo chalk. I can' t seem to find anything like it where I live but am going to look at a Lowe' s store tomorrow. What kind of chalk do the rest of you use on your box and boat paddle calls??