Phenol formaldehyde glue penetration into wood was compared in Norway spruce, birch, and aspen (<i>Populus tremula</i>) with a holding open time delay of up to 60 minutes between glue application and joining. Strength variability increased with increased holding-open time, but only to a small extent with two-sided application which gave generally stronger joints. Results suggest that joints should be closed before penetration is complete so that excess glue remains to lubricate the joint. -- AATA