A.This is one of the most difficult joints to glue. The epoxies and reactive hot-melts are better than water-based wood glues. (Reactive hot-melt glues are industrial glues that differ from typical hardware-store hot-melt glues.) Since the end grain of wood is very porous, water-based wood glues are easily absorbed into the grain, leaving little glue for bonding. A method for combating this is to thin some of the glue with water and use that to seal the end grain, then glue up as normal after an hour or so. There are some wood size products on the market that work to seal the end grain as well.
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