Hey everyone! I recently glued two walnut boards after planing both sides perfectly flat with my freshly sharpened No. 5 hand plane. The joint looked flawless, and I clamped it for 1.5 hours. However, when I removed the clamps, the boards came apart as if I hadn't used any glue at all. This was really surprising because I'd never faced this issue before. I decided to replane the surfaces and lightly sand them with 60 grit, then re-glued them, and this time it worked. I'm left wondering, can wood surfaces be too smooth for glue to bond effectively?
4 Answers
Totally agree! Smooth surfaces usually lead to much stronger glue bonds. Don’t worry too much about the smoothness—it sounds like you just had a quirky experience.
Actually, no! Smoother surfaces are typically better for glue joints. A smooth surface keeps the wood's pores open, allowing the glue to penetrate better. Sanding can clog up those pores with dust, which isn't ideal.
It's possible that too much clamping pressure can be the culprit, causing excessive squeeze-out. When the surfaces are extremely smooth, even if they look perfect, it might actually make it trickier for the glue to hold. Just something to think about!
I've never had this issue myself and I usually plane before gluing. What type of glue were you using? Could it be old or perhaps not suited for your wood type?
I used Titebond 2, which is less than 2 months old. I tried the same glue on the second attempt, so I don't think that was the issue. I always plane before glue-ups, and this time my plane was exceptionally sharp, too.
This is really confusing for me too! I've been woodworking for over 10 years and never had this happen.