Masonite is an excellent panel for painting both in oils and acrylics. It is prefered by many professional artists. It has to be treated first or it will suck up all your paint. You can use gesso or latex wall paint that you can buy in any paint or hardware store. I use white. It must be applied both sides and all edges. This seals and balances the panel so it is less likely to warp. I give each panel at least two coats each side, sometimes more. Allow to dry overnight before applying the second or third coat. If you apply the second coat in gray or some other color, you will not miss spots. White is hard to cover a second time without missing a spot or two.