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Discussion Starter · #1 · (Edited)
Hey Guys,

I'm having an issue with ridges forming along my joinery lines after I have completed a glued up table top. My boards are square edged and glued up flat with no filling. These ridges form between a month or 2 months after I have completely finished the project. So I end with a super flat and smooth surface complete with my finish, only to find that after a couple of months these ridges form.

I use Titebond III and Arm-r-Seal. These small ridges seem to be my clear coat finish, because I can go back and knock them down (very carefully) with a chisel. I'm guessing this is the wood acclimating to the area (my garage has a different humidity level than the table's final usage spot). Is this something people have seen before? And are there tips or things I can do earlier in the process to help eliminate this?

Thanks so much for the help and let me know what other details I need to provide. The pictures below are of a walnut table top with Arm-R-Seal Satin finish and a maple table top with Arm-R-Seal High Performance water base. I had these issues with both and with a few other tables (I mostly use oil based Arm-R-Seal).

The pictures attached were taken right after the projects were completed, so the ridges are not present. I tried to take some pictures of them now, with their ridges, but you couldn't see that small of a feature in a picture.

Thanks for any help!
 

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You may be able to photograph through a magnifying glass. My first thought is if the ridges are noticeable with a marble rolling across them...I would suspect the glue held the joints preventing further shrinking which occurred between the glue lines as the wood dried further and shrunk between the joints. That is common after taking wood acclimated to a damp environment and moving it to a dehumidified climate (say un air conditioned to air conditioned room).

Your tables look awesome by the way, Nice Work!
 
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Discussion Starter · #3 ·
At first I had no idea what to even search for, so I couldn't figure out my issues just by googling myself. But after looking again I'm finding a ton about "sunken joints" and "raised glue lines". I have a few things I'm going to try on my next table to help avoid this. I use biscuit joinery, and I'm going to try and use slightly less glue than I normally do. I'm also going to let my tables sit a couple weeks ago being glued up before sanding, and I'm going to let my tables sit in my house after sanding for a while before doing any finishing. Hopefully that will allow things to acclimate.

Thanks gmercer!
 

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Coincidentally, I was talking with a custom furniture maker last week and he warned me against using biscuits with glue. There can be problems with swelling.

(Personally, I've never used biscuits with or without glue).
 

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Oh really? Did he mean that he just didn't put glue on the actual biscuits themselves and just glued the boards themselves? Right now I put glue on the biscuit and the board surface so all contact surfaces do have glue including the actual opening the biscuit seats into.
 

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Biscuits swell when glue is applied to them. On boards that are really thin, the swelling will cause football shaped silhouettes in the surface. If they're still swollen when the wood is planed, it will create low spots when it shrinks. It doesn't sound like that's your situation.

Certain glues can affect the finish if they shrink or swell when they fully dry.
 

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Oh really? Did he mean that he just didn't put glue on the actual biscuits themselves and just glued the boards themselves? Right now I put glue on the biscuit and the board surface so all contact surfaces do have glue including the actual opening the biscuit seats into.

Just saw this. If you were replying to me--I don't know. He didn't say.
 

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Biscuits swell when glue is applied to them. On boards that are really thin, the swelling will cause football shaped silhouettes in the surface. If they're still swollen when the wood is planed, it will create low spots when it shrinks. It doesn't sound like that's your situation.

Certain glues can affect the finish if they shrink or swell when they fully dry.
So true...I've had some pretty frustrating projects using biscuits on plywood. They are my least favorite method of joint reenforcement.

One memorable moment was doing built in closet shelving, it looked great during the install but I wanted to die the next day when I saw how bad the swelling was. I almost pulled the trigger on a domino because of that job alone but I'm holding out until their patent expires. I still can't justify the price of those things.
 

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Sounds like you have gotten some good advise for dialing in this issue...What I was going to offer...was:

Watch the amount of clamp pressure you use (not too much!!!) and use just enough glue...again, not too much!

The other is...loose the "biscuits" they are worthless for strength and a simple peg can do aligning for you if need be...Better yet a spline or a spline and a free toggle like a "domino" system offers...

Good Luck...
 

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I'm more of the "..lose the biscuits" kind of guy. I do much better by just lining the boards up as I clamp - no biscuits, no dowels, no nothing.

The only time I use splines is on heavy office furniture where the top is double layered plywood at the edge and surrounded by a heavy solid wood edge like 2" thick or better.
 
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