Protective coatings which are used to inhibit corrosion of metal parts and to retard the penetration of moisture into wood parts and thus prevent fungus growth may be classified as follows: (a) Organic coatings; (b) Metallic coatings; (c) Application of chemicals which break down the outer layer or surface of the part and form new compounds which are more corrosion resistant than the original metal. This report deals with the materials which come under the first classification, namely enamels, which are generally manufactured from a varnish base by adding pigments. ... The Air service has [published] an approved list ... of manufacturers who have furnished samples ... which have met a satisfactory outdoor exposure test [and] a specification has been prepared which is used in conjunction with the approved lists [outlining appropriate] laboratory tests ... The acceptance of any shipment can be based on these laboratory tests, but in order to determine the actual serviceability of enamel an exposure test must be made on each sample ... [The purpose of this document is ] to revise the present approved lists of enamels and to determine the appropriateness of Air Service Specification 14028-B for aircraft enamels and make such changes, if any, as the results would warrant.