Since research in paint problems has developed the fact, that sublimed blue lead acts as a rust-inhibitive in paint for iron and steel surfaces, and since it has become a practice to bake priming coats as well as finishing coats on the metal parts of automobile bodies and even on steel cars, it will prove interesting to note, what can be done along this line. Naturally it would hardly seem practical or economical to employ a pigment like sublimed blue lead on the pressed steel of which ordinary coal cars are composed and yet, after giving the subject serious consideration, it may be found to be worthy of extensive trial. The first or priming coat would be nearly dead flat and when baked on the metal at moderate temperature, say 150 degrees, it would also be practically non-abrasive, and on account of its superior spreading properties, the paint the author has in view would not be out of reach on account of price.
Priming Coat for Steel Freight Equipment, etc. Pastel Mix and grind without overheating:
50 pounds sublimed blue lead;
American zinc oxide;
gas carbon black;
hard gum japan drier;
heavy petroleum naphtha;
78 pounds soft paste.
If the paint is to be used for air drying, it is best to thin the paste with enough pure turpentine to make 100 pounds. If for baking, it may be thinned with turps substitute. In either case the batch should make 7 gallons of paint, ready for application, after a thorough stirring. This primer will air dry inside of 4 hours and readily bake hard enough in 2 hours to admit of a second or finishing coat, which can be of the type usually specified by the various railroad corporations.