Shelling of Growth Rings at Softwood Surfaces Exposed to Natural Weathering

Abstract

Shelling is the delamination of growth rings and the projection of woody tissue from wood surfaces. Shelling disrupts coatings and makes refinishing difficult, and a better understanding of the phenomenon is needed to help alleviate its unwanted effects. We tested whether confocal profilometry could quantify shelling in flat-faced and profiled-faced western larch deckboards exposed to natural weathering and examined the effects of growth-ring orientation and angle on shelling. Confocal profilometry was able to quantify shelling in both deckboard types. Shelling developed at the surface of flat-faced deckboards oriented pith-side-up, whereas it was absent from boards oriented bark-side-up. We found an inverse correlation between the height of shelled growth rings and the angle of growth rings to the surface of flat-faced boards. Shelling occurred in profiled-faced boards oriented pith-side-up due to the delamination of growth ring tips and projection of latewood from wood surfaces. A superficially similar although less pronounced phenomenon was seen in profiled-faced boards oriented bark-side-up. The shelling of profiled-faced boards oriented pith-side-up created lanceolate-shaped slivers of latewood that projected from the peaks of profiles. Some of these latewood tips were sharp and, for this reason, we suggest that profiled-faced western larch deckboards should always be oriented bark-side-up rather than pith-side-up.

Surface Protection of Wood with Metal Acetylacetonates

“…Panels were scanned with a digital desktop scanner, as above, using the same instrument parameters used to scan thin wood veneers. Confocal profilometry (Altisurf 500 ® , Altimet, 298 Allée du Larry, 74200, Marin, Haute-Savoie, France) was used to measure the erosion of wood panels after weathering [22]. After outdoor exposure, stainless-steel masks were removed from panels.…”