I recently built a simple maple dining room table. I edge glued (using Tightbond type 2) random width 5/4 pieces together for the top and took the slab to a local shop to run it through their door sander. Finally, I sanded the slab using successive grits to 320 smoothness. Wow, felt great. I finished the wood using Mosers polymerized tung oil, followed the directions, screwed up, resanded, then refinished. I realized that it was time to bring it into the house. It’s been inside for a couple of months now. Everyone thinks it’s great, but I know better. I can feel all the joints on the top- like a little ridge where each board is glued to the next. The legs, which were glued up from 8/4 stock have the same problem. The table leaf, which resides in the shop, also has the ridges. There are a couple of factory made maple slabs in the house which we use as work surfaces which have been unaffected. Is this a tung oil problem? Glue problem? Wood problem? Summertime moisture problem?
Thanks for any help. Rick
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Replies
Rick,
I think it could be either (or both) of a couple things. The titebond could be swelling, especially if the glue lines were really thick to begin with (insufficient clamp pressure), and if the humidity was really low at the time of glueup. I've also noticed this effect when I've glued edge grain to face grain, like a slab-sawn board to a quarter sawn board. The different expansion rates of the two pieces will make one rise above the other enough to feel, moreso when the pieces are thicker.
Regards,
Ray
Ray, The humidity was really low at the time of gluing up the panels. It hadn't rained for a couple of months. I then brought it into the house and fired up the swamp cooler which was hardly conducive to the stability of the wood. Next time I'll try different glue and pay more attention to the way the wood was sawn. Thanks, rick
Rick,
Unibond 800 is also highly recommended for edge gluing, laminates and veneering.
Doug
The glue line ridges are a form of "creep" that is fairly characteristic of PVA adhesives. The Type II PVA's (Titebond II) seem to be most affected. It is a function of moisture content of the wood when the joints were glued and whether the panel has gone through a moisture change cycle.
If the glueline has expanded due to the wood's increased moisture content and then shrunk with reduced humidity, the PVA adhesive does not shrink with the wood in the joint.
In the shop I was involved with we finally stopped using PVA for panel glue ups. Adhesives with no creep are much better. We used a urea formaldehyde like DAP/Weldwood Plastic Resin and eliminated all the problem.
I had the same problem three years ago with Titebond II. I will never use it again unless the waterproof feature is the most important thing. In that case, I would probably us Gorilla. The Lee Valley cabinett makers glue is just fine.
Hans
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