Fig. 6From: Effects of preheating temperature, preheating time and their interaction on the sandwich structure formation and density profile of sandwich compressed woodEffects of preheating time and preheating temperature on the position of compressed layer(s). a Distance increment with each 15 °C elevation interval during 4, 8, and 12 min preheating time; b distance increment with each 4 min extension interval under different preheating temperatures. Distance means from the position of compressed layer to top or bottom surface of woodBack to article page