Author Topic: Raised Glue Lines  (Read 2910 times)

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Offline Owego

  • Posts: 114
Raised Glue Lines
« on: June 06, 2016, 11:40 AM »
I made an end-grain cutting board using Tite Bond III.  Sanded down to 220 using an RO.  Used suffix as a finish.  Two weeks later I notice all the glue joints are proud of the surface.  Not much but enough to feel and it is definitely a ridge as I can feel resistance in both directions across the  joints.  This has happened on both the top and bottom surfaces, but not on the side of the cutting board. 

So I'm thinking one of two things happened: 1) the wood has shrunk below the glue line, 2) the glue has swelled due to the surfix oil.  But I'm open to other explanations.

The woods used (cherry, walnut, maple) were all kiln dried and remained flush and smooth.  A previous board of similar design has not done this (raised glue joints) but it was finished with plain mineral oil.  Board is 45mm thick.

Tom

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Offline HarveyWildes

  • Posts: 788
Re: Raised Glue Lines
« Reply #1 on: June 06, 2016, 12:38 PM »
It's pretty common for a water based glue like Tightbond III to cause wood next to a joint to swell slightly.  The swelling is temporary, and the wood will slowly return to it's "pre-glue" shape over a few days.  A couple of times I have planed or sanded a panel more or less as soon as the glue dried, and then had a slight dip on the glue joint with an even less noticeable ridge (e.g. almost nothing - but almost nothing is, of course, something) right on the glue line a few days later.  I've never seen it on end grain, as end grain swelling and shrinking is normally insignificant relative to radial and tangential shrinking.

It would be interesting if the finish was affecting the glue.  I've never seen that with linseed or tung oil, and Titebond III is my general purpose wood glue.  For a finish, I general mix linseed or tung oil with poly and mineral spirits - high on the mineral spirits and low on the poly to start with, and reversing those proportions over 4-6 applications.  I'm sure that Festool's mix has more exotic ingredients that might interact with certain glues.

Offline ear3

  • Posts: 3594
Re: Raised Glue Lines
« Reply #2 on: June 06, 2016, 02:58 PM »
Was the one that sweleld using a mix of wood species.  On previous cutting boards I've done with multiple kinds of woods, I have noticed the development of ridges after a few days of letting it sit, which I just attributed to differential rates of shrinkage after cutting the board open.  I just resanded and reoiled.

I made an end-grain cutting board using Tite Bond III.  Sanded down to 220 using an RO.  Used suffix as a finish.  Two weeks later I notice all the glue joints are proud of the surface.  Not much but enough to feel and it is definitely a ridge as I can feel resistance in both directions across the  joints.  This has happened on both the top and bottom surfaces, but not on the side of the cutting board. 

So I'm thinking one of two things happened: 1) the wood has shrunk below the glue line, 2) the glue has swelled due to the surfix oil.  But I'm open to other explanations.

The woods used (cherry, walnut, maple) were all kiln dried and remained flush and smooth.  A previous board of similar design has not done this (raised glue joints) but it was finished with plain mineral oil.  Board is 45mm thick.

Tom
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Offline RJNeal

  • Posts: 333
Re: Raised Glue Lines
« Reply #3 on: June 06, 2016, 09:18 PM »
I have made more than 50 end grain cutting boards. I found the best results is to let the boards age,rest for about 3 weeks or more after final glue up. That pretty much solved the glue line problems.
I have sanded the boards after glue up and later came back for finish sanding only to find the boards have twisted or cupped.
Boards are like fine wine... Both need a little time
Good luck.
Rick
Have you walked your saw today?

Offline Holmz

  • Posts: 4010
Re: Raised Glue Lines
« Reply #4 on: June 07, 2016, 04:07 AM »
I made an end-grain cutting board using Tite Bond III.  Sanded down to 220 using an RO.  Used suffix as a finish.
...
Tom

Is Suffix food safe?
And is linseed or Tung oiled food safe?

Offline HarveyWildes

  • Posts: 788
Re: Raised Glue Lines
« Reply #5 on: June 07, 2016, 07:55 AM »
Is Suffix food safe?
And is linseed or Tung oiled food safe?

Good point -  I use walnut oil on any project related to food.