I will be mounting tree roots, an art display, on a surface to be displayed on an outside wall in full sun. What would the best type of paint be to use on the mounting surface and roots? Also, any suggestions on the mounting surface? I don't really have any particular type of mounting surface in mind, just something that will be smoothe and will hold paint. The roots and mounting surface will be contrasting colors. The display will be subjected to sun and rain. The display size will be about three ft. X five ft. I would have to use spray paint on the roots due to the varied surface. The roots, from hair thickness to about 1/2", should be sufficiently dry. I've been air drying them for 2 months.