This is my first attempt at painting the exterior of my house. I was advised to use Zinsser Primer Bulls Eye 123 to cover the previous oil base paint on the soffit and facia in order to prepare it to receive a water based latex. The wood is really rough, a sort of plywood finish. I am eventually going to paint it a dark chocolate color similar to the original color, so covering the color is not the problem. My question is: how thick must the primer be? Must the wood be turned completely white from the primer or can I have the darkness coming through?