While we are on the subject of French paint I have to say that Leroy Merlin’s own brand is very good. For Acrylic I don’t buy an undercoat, I dilute (with water of course) the ‘main’ paint I will be using. Had some very good results, especially with white, that I used at a friend’s house to paint over some old ceiling beams. Hasn’t yellowed at all after a few years of use including a poêle a bois in the room.