Rust-Oleum Specialty 30-oz. Black Flat Magnetic Latex Primer
The Rust-Oleum 30-oz. Black Flat Magnetic Latex Primer helps create a magnetic surface for hanging a variety of items including notes and photos. The primer can be applied to wood, metal, masonry, drywall or plaster and dries to a flat black finish in as little as 15 minutes for your convenience. The latex formula can be cleaned up easily using soap and water.
As others have stated you need to make sure the metal is stirred up well in this product. By the nature of it the metal sinks quickly to the bottom of the can. You need to use the foam roller as suggested (wish i read instructions before painting but as my wife says...I'm a man). This is not a quick easy project. But combined with the chalkboard paint makes a great play area for kids...although one has to wonder if teaching kids to write on walls is a good thing.