Colour-Based Prediction of Hardness and Microstructural Integrity in Beech False Heartwood

This paper investigates the colour and mechanical properties of European beech (Fagus sylvatica L.) false heartwood to propose a framework for its enhanced utilisation in interior furniture components. The primary objective was to examine the relationship between wood hardness and CIE L*a*b* colour coordinates across different false heartwood zones. Regression analysis revealed a strong negative relationship between the b* colour coordinate and Janka hardness (R2 = 0.716). Additional analyses of reflectance spectra coupled with scanning electron microscopy (SEM; Tescan Vega and UHR-SEM Tescan Amber) distinguished degraded from non-degraded zones based on their microstructural integrity. Microscopic analysis showed that early-stage colour changes occur without structural degradation or the presence of fungal hyphae, thereby preserving the microstructural integrity of the wood. Conversely, significant hardness loss was associated exclusively with advanced stages of biological degradation characterized by the evident presence of fungal hyphae within the wood microstructure. These findings suggest that optical parameters can serve as reliable, non-destructive indicators for the automated and objective grading of beech wood containing false heartwood, thereby optimizing its value and utilisation in the wood-processing industry.