On December 6, 1938, the French Air Ministry issued an official circular [Instruction No.1422], calling for the immediate camouflage of all land-based operational aircraft. Initially, the order only specified Kaki for the upper and side surfaces, and [Gris bleu clair] for the undersides. The [French Kaki] paint had in fact a more or less yellowish olive green shade. Both colours had a matt finish and were applied following a 'flowing' soft-edged demarcation line along the fuselage flanks and the wing leading edges.
As this measure was deemed insufficient, it was stipulated that these two basic shades were to be further mixed using [Vert fonce, Ombre calcinee, Terre de Sienne naturelle, Blanc, Noir], and even [Rouge] and [Bleu] in order to obtain various darker colours that should be applied in large soft-edged blotches, with no particular geometrical shape, over the upper and side surfaces of aircraft. As can be easily imagined, the resulting variations in tone and shade could only be described as almost infinite.
A certain degree of standardization was attained, however, with the issue of standard colour charts by the paint producers during 1939-1940. Thus, the [Gris bleu fonce] and the [Terre foncee], used almost universally thereafter in combination with the ubiquitous [Kaki], made their debut. In late 1941, a new official note instructed that the demarcation line between the upper surfaces camouflage colours and the undersides [Gris bleu clair] was to be re-situated higher up than before on the fuselage sides for a better air-to-air concealment.
The aircraft already in service were progressively camouflaged by the units during 1939, while the new machines got their camouflage finishes at the factories. The painting of the latter was made following the instructions issued by the [Direction Technique et Industrielle - DTI], which gave them, if not a perfect harmonization, at least a certain degree of uniformity according to series, type or factory. In general, the camouflage was applied without following a precise pattern, and although some types ([MB.174, LeO 451]), received a more or less homogeneous scheme, all that can be said for sure about the application of the [WWII French multicolour scheme] is that it remained fairly random throughout the entire war.
Note: Due to the lack of an official standard colour chart, the colour of French paints could have different values depending on the manufacturer or even the production batch. The samples above must be considered only illustrative, as the shades of the actual camouflage paints applied onto aircraft could vary slightly in hue.