Frank, thank you for your kind reply !
Fred, I'll help you as good as possible :
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Smog one :
- base color : white, yellow ocre, emerald green, ultramarin blue, burnt umber (for the darker areas in the base color add more ultramarin blue and burnt umber, better than just black in my opinion).
- brown camo : white, burnt sienna, burnt umber, a bit of ultramarin blue (softens the brown).
- green camo : white, emerald green, ultramarin blue, a bit of burnt sienna (softens the emerald green color wich is quite bright).
Smog two :
- base color : white, yellow ocre, burnt umber, just a bit of emerald green.
- brown : white, burnt sienna, burnt umber, a tiny bit of ultramarin when darker tone needed.
- green : ultramarin blue, yellow ocre.
It's a matter of good reference pics and a lot of fiddling with a brush in the paint, untill you are satisfied.
I hope this will help a bit ?
Greetz ! G.