The performance of 35 finishes (clear water-repellent preservatives; lightly pigmented, water-repellent preservatives; semitransparent stains; solid-color stains; and paints) applied to newly planed, vertical-grained; factory-planed, flat-grained; or saw-textured, vertical-grained western redcedar bevel siding was evaluated for cracking, erosion, and general appearance over 14 years of outdoor exposure at two sites (Madison, WI, and Gulfport, MS).
Previous information on the service life of finishes on western redcedar was obtained from studies of vertical-grained lumber from old-growth forests using finishes that are no longer available.
We report here the performance of 35 finishes used in 49 finish systems on newly planed vertical-grained; factory-planed flat-grained; or saw-textured vertical-grained western red-cedar bevel siding.
The vertical-grained siding was an all-heartwood clear grade having growth rates in the range of 26-28 growth rings per inch (10-11 per cm).
FINISHING -- Within each type of bevel siding (factory-planed flat-grained; newly planed vertical-grained; and saw-textured vertical-grained), the 4-ft boards were randomized, and three boards were used for each finish system.
DATA REDUCTION -- The data for each of the finish systems were plotted to show performance over the 14-year exposure on each of the three different surfaces (newly planed vertical-grained (NP VG); factory-planed flat grained (FP FG); and saw-textured vertical-grained (ST VG)).
For example, the service life of finish C-5 (solid-color oil stain, Figure 2) was about nine years on newly planed vertical-grained, 13 years on factory-planed flat-grained boards, and more than 14 years on saw-textured vertical-grained lumber.
In general, each of the finish systems had longer service life on the saw-textured vertical-grained bevel siding.
However, in general, the type of surface (smooth-planed or saw-textured, vertical-grained or flat-grained) had little overall effect on the general appearance ratings of these finishes (Group A-1 to A-14), primarily because of mildew growth.