• Julie Cool The University of British Columbia Forest Sciences Centre 2424 Main Mall Vancouver, BC, Canada, V6T 1Z4
  • Roger E. Hernández Université Laval Pavillon Gene-H. Kruger 2425, rue de la Terrasse Québec, QC, Canada, G1V 0A6


Black spruce wood, oblique cutting, face milling, helical planing, water-based coating, adhesion, weathering


Oblique cutting, face milling, and helical planing were used to surface black spruce wood prior to the application of an exterior acrylic water-based coating. Surface characteristics were assessed using an environment scanning electron microscope and coating performance was evaluated through pull-off measurements before and after a 3-year natural weathering exposure. Microscopically, oblique-cut surfaces were smooth with plateau-like areas, had a low level of fibrillation and few open lumens. Face-milled surfaces were characterized by a high level of fibrillation and numerous open lumens that favor coating spreading and penetration. Helical-planed specimens had an intermediate level of fibrillation and number of open lumens. After coating application, oblique-cut and helical-planed surfaces presented similar overall visual quality, whereas face-milled samples had an irregular appearance that degraded their quality. As a result, the latter were subjected to erosion during weathering exposure which further degraded their overall quality as well as pull-off strength. More specifically, face-milled samples had a significant inferior pull-off strength both before and after weathering. Oblique-cut specimens yielded higher initial pull-off strength but were associated with higher adhesion loss. According to the results, helical planing reduces adhesion loss of the coating studied over a 3-year exposure to yield a superior pull-off strength after weathering. Therefore, surfaces having a certain level of fibrillation still firmly attached to the surface and open lumens are desirable to increase mechanical anchorage of coating on black spruce wood surfaces.

Author Biographies

Julie Cool, The University of British Columbia Forest Sciences Centre 2424 Main Mall Vancouver, BC, Canada, V6T 1Z4

Assistant Professor

Department of Wood Science

Faculty of Forestry

Roger E. Hernández, Université Laval Pavillon Gene-H. Kruger 2425, rue de la Terrasse Québec, QC, Canada, G1V 0A6


Centre de recherche sur les matériaux renouvelables

Département des sciences du bois et de la forêt

Faculté de Foresterie, de géographie et de géomatique


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Research Contributions