How to do it
Step by step
- Take the joint fully apart and scrape off the old, failed glue.
- Dry-fit the parts; if the tenon is loose in the mortise, plan to fill the gap.
- Brush wood glue onto both surfaces.
- Reassemble and clamp square — check with a quick diagonal measurement.
- Wipe the squeeze-out with a damp cloth and leave clamped overnight.
Conditions
When the answer changes
A badly worn, wobbly tenon needs gap-filling epoxy or a wood shim instead of PVA. If the joint can't come apart, inject glue with a syringe rather than forcing it.