I have plaster ceiling in my master bedroom only and as I painted one of my wall dark color, I notice there will be white dust on that wall. After I clean it up, the white dust will appear again after a week. I think there are white dust everywhere in the room, just that it's visible on this wall cause it's dark color. Shouldn't be anything wrong with the paints, cause my other rooms don't have such problem, so I think it's because of the plaster ceiling - maybe the contractor didn't apply sealer?

Is there anyway I can remedy this? My plaster ceiling was already painted to match the other walls in the room.

But there's no problem with other rooms (that do not have plaster ceiling) and I used the same Nippon paint range for these rooms, just that the colors are different. The paint guy do not have to skimp on the paint cause I bought more than enough for him to use. Did you have the same problem too previously? After you apply the sealer, are there anymore white patches on your wall?