I guess its odd that I have had nearly 100% success painting pink foam board with spray paint.
I created this board as a base for my Heroscape by making all of the hex impressions and then spray painting with a dark color to create hex lines. I wish I had taken more pictures of the creation process, but I do have some pictures of the board before I painted the hexes green.
There were only 2 places that got damaged by the spray paint. I used duck tape to keep the boards aligned while I was laying in the hexes. When I removed the tape and painted those areas got damaged by the paint. Fortunately, they are on the border and no actual hexes were messed up. The key I found was to have light trigger finger.
Most importantly, I learned that whatever I am doing, I test things on a scrap or discarded piece before working on the project focal point.