Data show that sanded Douglas fir and southern pine lumber, sanded on present high-speed commercial sanders and then glued, will not pass tests for structural water-resistant gluelines. Sanded ponderosa pine can be glued for these applications. Techniques for detecting and evaluating the problem with physical tests and microscopical analyses are presented. Accelerated aging physical tests are required to detect a difference in glueline performance between sanded and knife-planed lumber. Microscopical analyses indicate increased gross surface roughness and cellular damage of sanded lumber as compared with knife-planed lumber. Effects of online processing variables such as feed speed, belt speed, grit size, and amount of wood removed per stage are discussed. Possible technical solutions to make sanded Douglas fir and southern pine structurally gluable are presented. -- AATA