The performance was about the same for both the flat-grained and vertical-grained smooth-planed bevel siding but was greatly improved for almost all finish systems on the saw-textured western redcedar bevel siding.
Nor had any work been done to compare the performance of these new low-VOC finishes on flat-grained bevel siding from second- and third-growth forests.
The flat-grained bevel siding was all heartwood select-knotty grade with small tight knots having approximately two to three growth rings per cm.
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, we found little difference between the newly planed vertical-grained surface and the factory-planed flat-grained surface with some exceptions noted in the following subsections.
In some cases, finishes on the factory-planed flat-grained siding gave better performance than on the newly planed vertical-grained siding, but this was not universal.
Note that the service life was higher at Gulfport and Madison for the factory-planed flat-grained siding than for the newly planed vertical-grained siding.
Little apparent difference was evident between the WRP-treated and untreated for the newly planed vertical-grained siding and the factory-planed flat-grained siding.