Once you have found the piece you are going to make in to a chalkboard, tape the inside edges of the frame with painter’s tape to avoid getting paint in undesired places. If the mirror or glass comes out of the frame, that is also an option to avoid the frame altogether by removing it and remounting later.
Stir the chalkboard paint and paint the mirror glass with four coats, allowing 20-30 minutes of drying time in between coats. You’ll want to get the corners done with a smaller paint brush. Make sure to do your painting away from little hands that could touch your wet paint.
Once your fourth coat of paint is finished, remove the painter’s tape (carefully, as not to get it on yourself) and prime your chalkboard by rolling chalk on it’s side on top of the chalkboard and erasing it.
To clean your chalkboard, an all-purpose kitchen cleaner with a paper towel will do.