Investigation of surface properties of poplar wood impregnated with lauryl alcohol after densification

Abstract

Impregnation and densification processes, widely used to enhance wood performance, can substantially modify not only mechanical properties but also surface characteristics. In this study, poplar ( Populus x canadensis) wood samples were impregnated with lauryl alcohol ( LOH) and subsequently subjected to densification (Dw). The resulting changes in color, gloss, and surface roughness were systematically evaluated. Surface color was measured using the CIE Lab* system, and color differences (Delta L*,Delta a*,Delta b*,Delta E) were calculated for control, impregnated, and densified samples. A Delta E value of 2.303 for control samples indicated minimal color variation, whereas LOH-treated samples exhibited a notable color change (Delta E = 10.84), primarily due to surface darkening (Delta L = -6.36) and a marked increase in yellow tones (Delta b = 7.49). Densified samples (LOH/Dw) showed trends like LOH-only treatment. Surface roughness parameters (Ra, Rq, Rz), measured according to ISO 1997, decreased significantly after both impregnation and densification, with the lowest values observed in Dw and LOH/Dw groups. Gloss measurements at 20 degrees, 60 degrees, and 85 degrees angles revealed that densified samples exhibited the highest gloss values, particularly at 85 degrees, indicating improved surface reflectivity. In contrast, LOH-treated samples showed lower gloss, while the combined LOH/Dw treatment resulted in moderate gloss enhancement compared to the control. Overall, densification played a dominant role in improving surface smoothness and gloss.