Hi GD
I see what you mean by the gris bleu colour. It might be hard to find a spray paint that matches this. I already have plenty of light grey and dark grey paints though.
Okay, vibrant poison green for the hull seems sure. As for the colour of the waterline strip, it's up to me whether I want it black or bright red, correct? Or do you think all French warships in service during WW1 would have had them painted black?
I found these Danton-class pictures which clearly show dark, black gun turrets:
Mirabeau
http://battleshiplist.com/battleships/f ... rabeau.jpg
Diderot
https://s-media-cache-ak0.pinimg.com/or ... 12ef88.jpg