Weathering Characteristics of Wood Plastic Composites Reinforced . Jul 23, 2016 . It was selected because it is the most common WF used in commercial WPC decking. Wood flour was sieved through a 40-mesh screen (0.425 mm) to remove the larger particles and through a 60-mesh screen (0.250 mm) to remove the fine particles. HDPE with a melt flow index of 33.0 g/10 min (according..