Investigation on wax-impregnated wood. Part 1: Microscopic observations and 2D X-ray imaging of distinct wax types

Abstract

The migration and deposition of hot melting wax in wax-treated wood is not described in detail in the literature, although such products are available on the market. In the present study, this topic was investigated based on pine sapwood (Pinus sylvestris L.) and beech (Fagus sylvatica L.). The behavior of three different waxes was studied by means of 2D X-ray measurements and scanning electron microscopy observations. The three waxes did not show distinct differences in their deposition patterns. An intensive wax deposition could be observed within the vessels, tracheids, and fibers. In P. sylvestris the ray tracheids were penetrated with hot melting waxes, therefore there is a lateral wood penetration from the outer to the inner wood. In general, no wax penetration was visible within the parenchyma tissue and epithelium cells. Cracks were detected within the wax deposits as well as secondary microcapillaries, which were visible between the deposits and the cell walls.

Exploratory study on the impregnation of Scots pine sapwood (Pinus sylvestris L.) and European beech (Fagus sylvatica L.) with different hot melting waxes

“…1, 4 and 6). The deeper penetration depth in the radial direction of pine can be explained by Buro and Buro (1959) and Scholz et al (2010a). These authors observed wax deposits in the ray tracheids of pine.…”

“…The acid number of wax 1 lies between 15 and 20 mg KOH g -1 , and it has a viscosity of 28 mPa s (q.v. Scholz et al 2010a). The importance of the polarity is obvious for wax 3 and wax 2 (Fig.…”

“…2 and 5) and show much lower penetration depth compared to that of pine. According to the cited authors, this could be explained by the absence of conductance for liquids via the parenchyma tissue (Buro and Buro 1959;Scholz et al 2010a). On the other hand, it is more difficult for non-polar particles such as carbon (Murmanis and Chudnoff 1979) or wax to cross the hardwood pits due to their membrane structure (Scholz et al 2010a).…”

“…Buro and Buro (1959) and Scholz et al (2010a) investigated the deposition of hot melting waxes in solid wood. They observed wax-free void space within the parenchyma tissue of pine and beech sapwood such as ray parenchyma cells or resin canals.…”

“…They observed wax-free void space within the parenchyma tissue of pine and beech sapwood such as ray parenchyma cells or resin canals. Furthermore, Scholz et al (2010a) investigated the uptake of different wax types in wood due to their molecule size and properties. These results and observations are the basis for further investigations in the present article.…”