For a batch of 50 gallons jet black locomotive enamel grind 13 pounds finest grade carbon black, that has been freed from moisture in a drying oven or kiln, in 12 gallons of a good grade of rubbing varnish through a water cooled mill as fine as possible, and when this soft paste has cooled sufficiently, place it in a liquid paint mixer, beating it with 3 gallons gum spirits of turpentine, then add gradually 35 gallons of long stock kauri varnish and strain through very fine mesh wire sieve or strainer. The rubbing varnish used in grinding may be replaced in part by say 4 gallons of a good coach grinding japan to 8 gallons of rubbing varnish and the latter should be short stock kauri gum of the 8 gallon oil variety while the long stock finishing varnish used for thinning is best for the purpose, when of the 20 gallon oil formula. The former practice of using genuine ivory black or drop black has been pretty well abandoned, because of its settling tendency, no matter how fine it was ground.
Follow the formula for black with the exception, that instead of grinding 13 pounds carbon black, only 9 pounds of the black and 7 pounds of chemically pure chrome green, medium are ground in 4 gallons coach grinding japan and 8 gallons of rubbing varnish. If any special shade of this green is desired, the proportions of black and green may be changed to suit or the shade of the green changed to light or dark as required.
This is usually green and the practice is that chrome green in japan is thinned with turpentine and so applied, drying flat and finished with clear varnish. However, this is not the rule with all roads and when cab enamel is called for it is wanted in ready-for-use form. The light or medium shades of chrome green are preferred and chemically pure green is the best to use for this class of goods to avoid sediment in the package. The following formula will give very good results:
Grind 25 pounds chemically pure chrome green light or medium shade, or a mixture of these shades as may be required, in 2 gallons of coach grinding japan, through a water cooled mill fine as possible and on the last run add one gallon rubbing varnish of not too dark a color. Thin the resulting soft paste, when cooled, with at least three gallons pure gum spirits of turpentine, then add gradually 42 gallons of a good hard drying varnish, that dries of itself within 12 hours. Result 50 gallons.