Behr Premium Concrete & Masonry Bonding Primer No. 880
For my last pick, I've changed directions slightly. This is a specialty primer, designed for use on masonry and concrete. These surfaces are highly porous, absorbing paint just about as fast as you can apply it. Without the right sort of primer, its easy to waste a lot of paint sealing off the surface of masonry surfaces. The other problem is gaining good adhesion, as some masonry surfaces are fairly crumbly (like mortar). This primer also acts as a bonder, helping to strengthen these surfaces and help them to last longer. Moisture in the masonry can wreck havoc with paint as well, causing it to peel. With this primer, your paint will have optimum adhesion to these difficult surfaces.