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Stumped with Arm-R-Seal

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Forum topic by Jarmo posted 05-31-2018 11:34 PM 776 views 0 times favorited 11 replies Add to Favorites Watch
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Jarmo

34 posts in 1827 days


05-31-2018 11:34 PM

I recently completed a table in cherry. The board for the table top were glued up using Titebond Liquid Hide Glue.

I finished the table top with 3 or 4 (can’t remember) coats of satin Arm-R-Seal, with the last coat being applied about 3 weeks ago. The finish seemed to be raised a bit at the seams of all the glue joints, enough to be easily felt by hand. A few days ago I wet sanded the table top smooth using 400 grit on the ROS and a mixture of mineral spirits and mineral oil, which smoothed everything out nicely. Since then the finish is again raised up at all the seams, enough to catch your fingernail on.

What’s the deal? I’ve never had this happen before.

I’m in Maryland and it has been 80-100% humidity for the last few weeks.

Could the humidity be affecting the finish?
Could the expansion of the wood be somehow causing this? The top has expanded approx 1/8” in 3 weeks.
Could the glue be expanding in the humidity and forcing the finish to pop up?

I’m assuming this will stop eventually, but it’s just strange to me.

Any ideas?


11 replies so far

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Tabletop

139 posts in 1231 days


#1 posted 06-01-2018 01:33 AM

According to rep from titebond, as the wood moves the glue does not. However that doesn’t explain your situation. My situation was wood shrunk exposing a slightly raised glue line.

With that said I’m sure it’s the glue and at some point it will become more stable. For now just keep buffing it out.

View wncguy's profile

wncguy

455 posts in 2796 days


#2 posted 06-01-2018 01:20 PM

Similar shrinkage to Tabletop.
I had a glue up with maple, walnut & cherry laminated together. Box was finished with Arm-R-Seal. After very dry stretch you could feel a slight ridge where boards were glued. For me I’m pretty sure it was the moisture changing in woods differently. Not due to finish or the glue.

-- Any man can be a father, but it takes someone special to be a Dad

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ChefHDAN

1443 posts in 3333 days


#3 posted 06-01-2018 01:45 PM

I just went & checked, (I’m in southern MD) and I’m a bit surprised to find a minute raised glue line on some of my tops. Ironically it’s not consistent for the entire joint and does not show on thin panels, just the 1” or so thick tops. Looks to occur at joints where grain is not parallel. Mine are TBIII with a BLO & WB poly finish…..

-- I've decided 1 mistake is really 2 opportunities to learn.. learn how to fix it... and learn how to not repeat it

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builtinbkyn

2942 posts in 1424 days


#4 posted 06-01-2018 02:02 PM

Could it be the wood is expanding due to more humid conditions than when the table was glued up and the glue is now being squeezed out of the joint? Just spitballing.

-- Bill, Yo!......in Brooklyn & Steel City :)

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Lazyman

3883 posts in 1871 days


#5 posted 06-01-2018 03:03 PM

Is the grain orientation about the same on either side of the joint? If one side is quarter sawn and the other rift sawn for example, I could see you could get what feels like a slight ridge if the moisture content fluctuated.

More spitballs. Close up picture looking down a seam might help.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

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pintodeluxe

5975 posts in 3297 days


#6 posted 06-01-2018 03:32 PM

I agree with some of the other folks here, it may just be expansion and contraction of the lumber. It’s especially noticeable on thicker tops. Boards move individually… even if they are part of a tabletop glueup.

Starting with lumber that is kiln dried to a uniform moisture content of 6-8% helps, but I don’t think you can escape it regardless of glue or finish type. It’s just one of those things that proves it’s a real wood top.

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

View Lazyman's profile

Lazyman

3883 posts in 1871 days


#7 posted 06-01-2018 03:59 PM

I got curious and after doing a little research, this sounds like classic PVA glue creep, though I have never see this myself. Some of the usual suspects are:

  • Wood was not dry enough at the start (10% or less)
  • Not waiting long enough (a week is recommended by some) after glue-up to let glue moisture escape and wood to stabilize before applying a sealing finish
  • Significant moisture swings
  • Joints between different types of wood and/or different grain orientations

Unfortunately, MC changes can cause this over time even if you have done everything right. Supposedly, hide glue won’t do this but PVA is notorious for it under the right (wrong) conditions. Short of striping off the finish and letting the top stabilize, there may be nothing else you can do.

Did you seal the underside of the table top? If not, that could play a role, especially since you said that the humidity has been high lately.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

View EarlS's profile

EarlS

3033 posts in 2832 days


#8 posted 06-01-2018 05:07 PM

I’ve had this happen several times with Titebond. I tried everything Nathan mentioned and still got glue lines. I even sanded things back down after they showed up and refinished, only to have them reappear. My solution is to use Gorilla glue (ploy-urethane) when gluing up boards that are butted up together. It doesn’t have the problem and the joint is probably stronger as well.

-- Earl "I'm a pessamist - generally that increases the chance that things will turn out better than expected"

View pintodeluxe's profile

pintodeluxe

5975 posts in 3297 days


#9 posted 06-01-2018 06:54 PM

I have taken oversized panels to an industrial shop with a 50” wide drum sander. The glue had cured for a few days before it was sanded. The panels came out of the drum sander flat, smooth and straight. Perfect.

In time (months) small ridges will develop at the joint lines. That’s seasonal movement. It’s usually not a problem with 3/4” thick panels, but can be noticeable on 5/4 and thicker panels. Some panels do it, some panels don’t. I really believe that if you start with wood that wasn’t adequately dry (or picked up some moisture in the shop) it magnifies the problem.

Your experience may vary.
Good luck with it.

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

View Rich's profile (online now)

Rich

4845 posts in 1073 days


#10 posted 06-01-2018 06:59 PM


My solution is to use Gorilla glue (ploy-urethane) when gluing up boards that are butted up together. It doesn t have the problem and the joint is probably stronger as well.

- EarlS

Polyurethane glue is only 58% as strong as PVA according to Fine Woodworking No. 192, July/August 2007. Patrick Edwards has the glue test article on his Old Brown Glue site:

http://oldbrownglue.com/images/articles/HowStrongisYourGlue_FWW.pdf

-- There's no such thing as a careless electrician

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Woodknack

12894 posts in 2864 days


#11 posted 06-01-2018 07:12 PM

Jarmo, how were the growth rings oriented? I had this happen in a table and didn’t understand it until Rich posted an article by Tage Frid. In my case, I had ripped a flatsawn board into strips and flipped it to make a quartersawn panel but two of the boards I joined barkside to pithside and just as Tage predicted, they expand/contract at different rates and sometimes there is a seam I can catch with a fingernail. Even if you didn’t rip and flip, it could possibly happen if you have rift or quartersawn joined to flatsawn.

-- Rick M, http://thewoodknack.blogspot.com/

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