Mary, how paint will read is determined by many factors, including what direction a room faces, the furniture in the room, the light factors in both the room and outside , how each person sees color, and of course, the paint itself. I normally do not recommend toning paint (adding white) to achieve a lighter look. The reason is that it is that, as Lori points out, it is a guess as to whether or not it will work and I can predict better from a paint chip. However, sometimes clients want to try it. Ironically, I just had a client paint a room SW Requisite Gray. She is one of a only a few of my clients willing to paint her ceiling. She wanted to try Requisite Gray at half. It turned out perfectly. Does that mean it would work in your space? You cannot be sure. I always recommend painting on a piece of lightweight drywall instead of on the wall or ceiling itself. That way, you have the opportunity to move the piece of drywall around the room at different times of day to see if it will work for you. Much success to you in your project!

Would you do simply white walls with super white ceilings and trim? Won’t the contrast make the walls look yellow? I would in a heartbeat. It's a very pretty combination. There's enough difference in Chroma that one won't make the other look dirty/dingy. But, yes, Simply White is more colorful, has more Chroma than Super White and it is yellower. The contrast of hue between the two could result in Simply White looking like a very pale creamy off-white. Considering the floor, I'd go with a little more color on the walls. Shoji White, Greek Villa kind of pale, subtle greige-y vibe.

Why would you want the screens painted black? It might interfere with the view, and the feeling of just a black edge/frame. Casement windows open fully, although there are some types with large windows with one big fixed pane, and tilt-out separate smaller bottom section; or a fixed middle pane and casements on either side. My post was in response to the one above mine by Greta An that suggested just do the inside of the window casing. This is another way to achieve a similar look but only if you have full window interior screens. Judging from the pictures posted for this question, those are not casement windows she’s debating about painting black. ...So what I suggested wouldn’t work for her windows...

Hi sorry no one has answered yet, did you go through with anything yet? I think it’s not easy giving advice on white without being there in person. However, there can be some clues like lighting conditions / direction of window facing, uou said you are using terracotta, so you can find something with an orange, red or yellow undertone in it and avoid anything with blue or green… unless you want it to stick out. I think you getting samples is a great idea. I found light colors arent easy because it can have indertones that you might or might not expect to show up & can look dofferent from room to room. Shoji white I think has green undertones, but depending on the light snd surroundings, it can look different. you can see how you like it and maybe play with some color cards on the fsn deck first and look at the darker version on each to see what undertones are at play, but thats just the start. Do update when your finished!