We repainted a wall that had been painted 12 years ago. I washed the walls well, used Mr. Clean eraser on crayon and other spots and washed again with water. When we painted, the paint separated in some areas and shows several areas where the paint wouldn’t cover. We used a stain blocking primer and the primer doesn’t stick to these spots either. What is the next step? Thanks for help on this.
Definitely some kind of contamination interfering with the primer. Try a tinted shellac primer, might take 2 coats. Also, if your walls are smooth, no texture, sand the affected areas with 150 grit paper or medium sanding sponge. This will help get things to stick.
I'm also wondering if the Mr. Clean eraser left a residue. Do you noticed this problem mostly where the eraser was used?