Foam board, often called foam core, is a sturdy board created with two thick pieces of paper laminated to a core made from foam. Boards come in a variety of sizes and thicknesses with different finishes on the outer paper. Foam core is a wonderful material due to the fact it is study yet lightweight. The board can be used in a variety of applications and is a great surface for painting.
Select a type and thickness of foam board based on how the painting will be used. Thicker foam board is more durable and can withstand warping and transportation. A thinner board might be suitable if you do not plan to transport or handle the painting a lot or plan to secure the painting in a frame. It is recommended to get a matt finish on the board to ensure the paint will stick properly.
Cut the foam board to the size needed. Be sure to use a straight edge such as a metal ruler and a very sharp craft knife -- a dull blade will cause the foam core to have a torn or chewed look along the edge.
Prime the foam board with a neutral base coat using a material like gesso. Be sure to get gesso that is suited for the type of paint you plan to use.
Once the gesso has dried thoroughly, draw an outline of a design you like. This will act as a guideline for the final painting.
Begin to apply paint in the pencil guidelines. Do not add too much water to the paint as it might get too wet for the outer layer of the foam board. Add matt or gloss medium to thin the paint.
Allow each layer to dry before applying the next layer.