Grind a soft base as follows:
pure graphite of 85% carbon;
bodied linseed oil;
color grinders' (hard gum) japan;
Thin this paste, when sufficiently cooled, with 2 gallons hard gum rubbing varnish and 2 gallons pure spirits of turpentine. Result: - 9 gallons of dove gray paint, weighing 14 pounds per gallon, that will permit any good paint applied over it to adhere to the metal indefinitely.