Alittle while back I posted asking for colours for Austro-Hungarian shell, and as always, received really helpful replies.
I mentioned that I had some information on colours for French shells. I must apologise to the fellow-lister who sent mer this as I've mislaid his details, but the following is taken from a US Publication Notes on French Ordnance 1717to1936, by Capt. James E Hicks. I believe it was published c. 1938.
Given the low rate of change in French kir from 1918 to 1938, I think it's possible to be faily confindent that these colours would be Ok for 1918, if not earlier. The text gives only a selection, but in lieu of anything else, may serve as a guide.
220 Mortar - "charge en nitrate" = shell has yellow head, red body.
220 Mortar - "Charge en nitre" - all yellow
155 GPF - as above
75mm AA - Shrapnel - Red with blue tip or red, blue tip grey band about half way down
75mm Mountain Gun - As 155GPF and 220 Mortar
65mm Mountain Gun - HE as 155 GPF etc, Shrapnel all red; drill rounds blue
Just when this looks like setting up a handy system - HE = yellow or yellow and red, shrapnel = red a table states
Explosive - 1900/1915 = Yellow/Red
Explosive 1918 - yellow/black
Shrapnel - Red
Shrapnel "charge in body" - white
Fragmentation m1910 - unpainted head (ogive) orange yellow body
Gas - black head, green body
Incendiary - Red ogive, green body
Practice - Black with blue band
Hope this helps: I don't claim its definitive, and I've not been able to cross-check it, but its source does seem to be French texts from at least 1938.