Supervisory Research General Engineer

Unfinished and finished fiberboards prepared from untreated and acetylated (IS weight percent gain) aspen fibers were exposed to accelerated or outdoor weathering. Acetylated fiberboards swelled less than untreated fiberboards after weathering. Acetylated fiberboards were smoother than untreated ones after treatment, and acetylation helped retain surface smoothness of both finished and unfinished fiberboards after weathering. Finished and unfinished acetylated fiberboards also had less mildew growth after outdoor weathering compared to untreated fiberboards, demonstrating the greater bio logical resistance of the treated boards. A penetrating semitransparent oil-based stain did not perform as well on acetylated fiberboard as on untreated fiberboard because the finish could not penetrate the treated surface. Therefore, not as much material could be applied to the acetylated boards. Film-forming finishes (paints and solid-color stains) performed equally well an acetylated and untreated boards after 2 years of outdoor exposure