Fig. 4From: Effects of preheating temperature, preheating time and their interaction on the sandwich structure formation and density profile of sandwich compressed woodSoft X-ray images and SEM micrographs of transverse section of sandwich compressed wood. Three sandwich structure formation types: (I) surface layer sandwich compressed wood, (II) internal layer, and (III) central layer; a, c, e magnifications of compressed layer; b, d uncompressed layer; f both compressed and uncompressed layersBack to article page