Finish carpentry relies heavily on glued miter joints, which means you’re gluing end grain. The problem is end grain sucks up wet glue more readily than edge grain, leaving little glue for bonding the two sides of the miter. But you can get a better bond with glue sizing. Here’s how to do it: Apply a thin layer of glue to both sides of the miter joint and then immediately wipe the glue off so the pieces look dry. Set them aside for the remaining glue to dry fully—usually about 2 minutes— then reapply glue and assemble the joint as normal. The thin layer of glue sizing prevents the end grain from taking up all the glue, resulting in a much stronger bond.
—Jon Proniewski, Menomonee Falls, Wis.
Edited and Illustrated by Charles Miller
From Fine Homebuilding #292
More gluing tips:
The Glue Roller – Easy and professional way to spread glue.
Use Glue to Fasten Blocking For a Drywall Patch – When there are hidden pipes or wires you need to avoid hitting, this tip is a simple way to install backing without using screws.