Mix and grind fine as possible on water cooled mill:

4 pounds finest jet carbon gas black;

12 "

bodied drying linseed oil;

20 "

color grinders' japan;

36 pounds.

Add enough good rubbing varnish to the above to make 40 pounds of material, which thin with 4 gallons gum spirits of turpentine and 5 gallons good turpentine substitute. Result 13 1/2 gallons. If selling price permits doing so, omit the substitute turps and use 9 gallons gum spirits.