What ifurita said....
Yeah, if you want to coat a smooth surface, and use it to stick small light refrigerator magnets on, it works well.
(great projects for kids!).
If you want to use it to paint cases or surfaces and hope minis or models with magnets on the bases will stick to it - not enough ferrous materials in it to work.
(and no, use more coats does not work well either).
Now, as a guy who magnetizes tons of stuff.....did you have a project in mind?