What to do about joints separating.

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Forum topic by SmithRanchFurn posted 09-16-2015 09:28 PM 882 views 0 times favorited 5 replies Add to Favorites Watch
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1 post in 982 days

09-16-2015 09:28 PM

Topic tags/keywords: rustic joinery moisture content shrinking question

I built this table top gluing each 2x block to plywood base and gorilla glued each block joint. I cut each joint using a tablesaw, I dont own a joiner. Each piece is stained and the table is sealed with three coats of polyurethane. After a few months now, even though I used kiln dried wood, my customer has noticed the joints are slightly gapping and separating due to moisture content I suspect.
I build rustic pieces and I expect to have imperfections, but I want to see if there is something to place in these areas that can stop the wood from shrinking. i.e. Epoxy, glue, etc. ?? or how extensive can the shrinking become with kiln dried pine?

5 replies so far

View AandCstyle's profile (online now)


3052 posts in 2255 days

#1 posted 09-16-2015 10:46 PM

Unless the wood will live in a humidity controlled space, it will shrink and expand with the changing humidity. Your design was a disaster waiting to happen; the plywood substrate will not expand/contract significantly but the 2x pine will move. How much depends on the change in the ambient relative humidity.

You might be able to make these successfully by gluing the 2x’s together to make a single panel and then capturing that in a frame without the ply substrate, somewhat like traditional frame and panel construction. HTH

-- Art

View joey502's profile


535 posts in 1516 days

#2 posted 09-16-2015 10:49 PM

Are the pieces of 2x material glued to the plywood 1 1/2” thick still or have they been planned down? How thick is the plywood?

I think you a couple problems with the table top moving on you. First is the level of humidity in parts of Texas, the wood is expanding and contracting with changes. Coating wood with a film finish like poly will not stop the moisture content from changing, it will slow it down but not stop it.

Second issue is the switching directions of the grain/ boards. The border around the table itself and the border around the center are moving in a different direction than the rest of the table. Wood more across the grain that is does along it. Framing solid wood with solid wood is going to be a problem.

The gorilla glue is also a concern to me. Polyurethane glues expand as the cure, foaming out of the seams, pushing your pieces apart.

How wide are the aprons the top is attached to? Is the wood movement causing the table top to cup or twist? A lot of time gluing wood thicker than about 1/8” to plywood is going to be problematic.

View JayT's profile


5631 posts in 2209 days

#3 posted 09-16-2015 10:54 PM

+1 to Art’s explanation and advice.

The other thing to consider is that kiln dried construction lumber is still usually around 19% moisture content. Though fine for construction, that’s pretty wet for furniture building. If you can buy the lumber well in advance and let it finish drying in your shop for a few months before using it, that would help, as well. A bunch of it will likely twist, bow and otherwise warp on you, but it’ll be more stable once you start using it.

Good luck

-- In matters of style, swim with the current; in matters of principle, stand like a rock. Thomas Jefferson

View pintodeluxe's profile


5659 posts in 2811 days

#4 posted 09-16-2015 11:04 PM

Tables like that, built from sections of short lumber, can be glued together. Omit the plywood next time and it will work out better.
Also, don’t wrap solid wood with edging across the end grain. That will usually fail unless specific techniques are utilized such as breadboard ends or frame and panel construction.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

View mahdee's profile


3883 posts in 1766 days

#5 posted 09-17-2015 01:04 AM

Looks like tongue and groove flooring material. They are usually nailed to the sub-floor so they can move. No glue needed.


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