I have been wanting to mess with this for awhile now. A friend of mine had a can of magnetic chalkboard paint, which was lucky for me because did you know the pint costs something like $20 at Home Depot or Lowes?!!? My husband is a tile contractor, so finally I was able to make use of his unsanded grout leftovers. Anyway, here is how I did it:
1. Tape off the desired area on the back of your painted surface (in my case, it was my kitchen-garage door) using Frog Tape. *Tip: Use a level to make sure you have straight lines and 90 degree angles.
2. Following the instructions on the can, I did the first coat of magnetic paint only. I applied a thin layer with a roller.
3. Allow the first coat to dry for 30 minutes.
4. Then mixing a ratio of 3/4 cup paint and 2 tablespoons of unsanded grout, apply the second coat.
5. Allow to dry for 30 minutes.
6. Remove the frog tape carefully. I find that doing this while wet works best.
7. Use some leftover trim or shoe molding to create a the frame; cut the corners on a 45 degree angle. I am going to paint mine green to match the rest of the trim in the kitchen.
I mixed the unsanded grout directly into the magnetic paint because I liked the dark grey chalkboard color. If you want to use a different color, you can do the second coat of magnetic paint, and then a third coat with desired color + unsanded grout to create the chalkboard consistency needed.