Testors Enamel Paint 1/4 ounce Graphite Gray Metallic by Testor Corp. If you are airbrushing Testors Enamels, use 8824 or 8825A Enamel Airbrushing Thinner Use the following ratio as a starting point Gloss: 3 parts paint to 2 parts thinner Flat: 3 parts paint to 1 part thinner Enamels require 48 hours to complete cure.