Like Dewey, I've never heard of it. However, according to the custom call maker, Billy White of White Hunter Game Calls, the only chalk one should use on boxes is white because it has no color pigment that contains the culprit, oil. I will say that I have used colored chalk and have "gotten away" with it. It seems that call makers that sell the colored chalk wouldn't do it if it would run the calls they're sellin'. Just sayin'
"Chasin' gobblers has a lot in common with dealing with a wife, 'bout the time ya' think ya' got 'em figured out, they change the rules!!!"