All glue types
Glue type
Polyurethane
Waterproof and multi-material. Expands as it cures, so use a light touch and clamp well.
Best for
Where it works best
Wrong toolVisible glue lines — it foams as it cures, and the expanded foam is weak and ugly.
Using it
What actually matters
- 01Dampen one surface first — moisture triggers the cure.
- 02Use sparingly; it expands two to three times as it sets.
- 03Clamp hard and leave it — the foaming stage pushes parts apart.
- 04Scrape or sand the cured foam; it paints poorly.