Simple test methods show that the surfaces of spruce and pine degrade rapidly on exposure and that after only one month of outdoor exposure the woods' paint holding properties are affected. Further weathering makes the condition worse. Latex paint does not adhere well to a weathered surface; alkyd paint fares better but not as well as on new wood; primers with good penetrating strength do not improve the performance. Planing the weathered wood surface to a depth of one millimeter is necessary for the paint to adhere well. The performance of coatings on wood that has been made porous due to attack by microorganisms can be improved by saturating the wood with a very low viscosity penetrating primer.