Mapping process-related chemical variation in resin-treated wood on different spatial scales

Impregnation-modification of wood typically results in an inhomogeneous chemical distribution, which reduces the effectiveness in wood protection. Macroscopic gradients in modification degree from the centre to the surface of boards create stresses that lead to honeycomb splits and cracks (Klüppel and Mai 2013). On the micron level, the penetration of the modification agents into the cell wall is a prerequisite for a sufficient dimensional stability (Altgen et al. 2020) and decay resistance (Biziks et al. 2020). A spatially resolved quantification of the modification degree is thus an important step towards developing more efficient treatments that result in a homogeneous chemical distribution. Here, two chemical imaging techniques that differ in their lateral resolution and field of view were combined to map the distribution of phenol formaldehyde (PF) resin in impregnation-modified wood on different spatial scales. Hyperspectral NIR image regression quantified the PF resin distribution across board sections, and this was combined with cellular UV microspectrophotometry (UMSP) on the cellular level within selected regions.