I recently purchased a 1930's home. Every room in the house has horsehair plaster walls and ceilings. The walls are speckled with black dots. We are about to embark on painting all of the walls (after hours of removing wallpaper and washing the walls). I am afraid that the black dots, which I am assuming is the horsehair peaking through, is going to show through the white paint. Will a good primer solve this problem? Any advice on how to deal with painting horsehair plaster would be appreciated.