What year did Edward Binney and Harold Smith invent crayons?

Edwin Binney had created this "black crayon" in a sense. It was called Stayonal = "Stay on all" and they used to mark boxes for shipping. It sold so well with other companies that they had the idea to test more with the product.

At the time they also had made a new type of slate school pencil and when at the schools they noticed that the kids needed something to color with. So they took the idea of Stayonal (made of wax) and made it smaller, less toxic, and changed the pigment color.