I am currently remodeling a bathroom and am ready for painting after removing the old vanity and furniture. I have several questions regarding the prep work.
a) There are white thick stuffs (about 1/16") beneath the old paint (the arrows shown in the photos below). They are located over the drywall and easily sanded. What are they? Is there anyway to easily remove them without sanding which would cause a lot of dusts?
b) Should I completely scrape off the old paint before applying a primer? Or, could a primer be applied over the old paint?