Fig. 3
From: Effect of density on the hygroscopicity and surface characteristics of hybrid poplar compreg
Roughness of untreated wood and compregs of different densities (A untreated hybrid poplar; B 0.60 g/cm3; C 0.71 g/cm3; D 0.80 g/cm3; E 0.90 g/cm3; F 1.01 g/cm3; G 1.10 g/cm3; H 1.20 g/cm3). The average values of roughness with different letters on the column indicated a significant difference at p < 0.05 (analysis of variance (ANOVA), followed by Duncan’s multiple range test)