"Wax crayon" refers to a colored drawing tool made of wax in a stick-like shape that is used to make colorful marks on paper or other surfaces. Full definition
He draws in white wax crayon on paper covered with wet chalkboard gray paint — a favorite wet - dry technique — to creating wobbly spirals, tumbling figure eights and lasso - y loops that suggest an artist working on a tightrope. (nytimes.com)
I have a thing with wax crayons I like our set in the art caddy to be whole — so any broken crayons get put into a container which I have all sorts of plans for. (rainydaymum.co.uk)
Here, however, he replaced the white wax crayon with red paint evocative of both blood and wine. (dreamideamachine.com)