Heinkel He.III Luftwaffe bomber.
The existance of the Luftwaffe was first revealed by Germany in February 1935 and until that time it had been building in secret,since the Treaty of Versailles conditioned Germany to building only civil aircraft.Such types as the Heinkel III,easily converted to a bombing role,were built as civil transports.The civil registrations looked strange on the Dornier Do.17 & Heinkel aircraft being flown with early segment camouflage consisting of steel grey,dark green,mid green and brown done in a curved pattern on the upper surfaces of the aircraft,later this was changed to a straight splinter camouflage,prior to this factory finished machines left the works in an overall steel grey and the additional camouflage was usually added in the field in many variations with the squadrons.
In 1936 the German Air Ministry had invited tenders for large quantities of dopes and paint finishes,the winning company was called Ikarol,this company produced huge quantities of basic brown primer,camouflage green,aluminium base silver,light blue,white and sea green,they also developed a finish similar to the British velvet black RDM2 called 'caput mortum' meaning dead black.
Dark green uppersurfaces with light blue undersides were normal for most German bombers in the early war years,progressing to the splinter camouflage finish mentioned above.Another way of quickly changing the finish from a daylight bomber to one suitable finished for night operations was to spray on a temporary coat of black,this was made from non drying glyptal resin which would easily hose off if required quickly for other tasks.