Popular Science, marraskuu 1933
Combining crayons and water colors, a new outfit for children has been introduced into this country from England. All of the crayons leave black lines when they are used to trace the outlines of pictures. But, when a brush, wet with clear water, is drawn ower crayon lines, they turn into water-color paint, producing the color indicated by the label. They are then spread like ordinary paints.