There are lots of benefits to choosing rigid boards instead of rolls or batts. One of them is that you can apply paint directly to the board.You can only paint foil-faced insulation if you prepare the board, however. Foil facings are nonporous, which means that they will not hold the paint. If you pre-treat the facing with galvanised metal etching primer, you can expect a better result. Always consult with a professional before painting a rigid insulation board. The painting process might involve dangerous chemicals that are better left to the professionals.