By Paul Lucas
SAM SUBS S EC T ION
During the course of my articles dealing with the camoulage of British military aircraft, I have made frequent reference to the various Air Ministry Directorate of Technical Development (DTD) Speciications for aircraft inishing materials. It has been suggested that a short summary of these speciications might be useful. The listing given here for the Second World War period is arranged in numerical order. Contrary to what was implied on page 79 of the author’s book ‘Battle for Britain’ these speciications along with the letter suffix ‘C’, which denoted a Cellulose inish or ‘S’ which denoted a Synthetic inish, were not marked upon the aircraft until 1942. The DTD Speciication Number marking was introduced by DTD Technical Circular No. 293 entitled ‘Identiication of Camoulage Finishes’ dated 28 June 1942. The letter ‘C’ or ‘S’, which appears at the end of the following paragraphs, denotes a Cellulose or Synthetic inish respectively. DTD 63A Material Speciication for Cellulose Enamels and Primer, which could be used on metals or timber, was issued in April 1939. Originally speciied to have a glossy inish, the speciication was changed in March1940 to have ‘reduced gloss’ to give a smooth satin inish pending the introduction of Type ‘S’ inishes in the other DTD speciications in use at that time. It superseded the original DTD 63 of March 1927. (C)