A study of the durability of roofing made with Asplund wood fibers was conducted from 1942 to 1967. Concentrations of 0 to 60 percent wood fibers (oak or pine) prepared by three variations of the Asplund process were evaluated. All the mineral-surfaced roll roofings and shingles were performing well after 25 years, with only four specimens showing more deterioration than the controls (only rags and paper in their felts). No differences in performance could be related to the felt composition. (Author)