Popular Mechanics, marraskuu 1951
As blackboard paint made from the following formula can be used on almost any smooth surface, it is especially suitable for painting a section of a shop wall on which bulletins, production notations, etc., can be chalked. To make the paint, mix lampblack, 2 oz., fine pumice stone, 8 oz., boiled linseed oil, 16 oz., and enough turpentine to make four pints. When applying the paint several coats will be required. Let each coat dry and then sand it smooth before applying the next.
Frank M. Butrick, Jr., Alma, Mich.