Replies

1. 
   Samson | Sep 24, 2008 10:12pm | #1

   Guess you'll have to wait for a power tool guy come along.  I own an ROS, but I can't remember the last time I used it - must be years now.  I use planes, scrapers and handsanding pretty much exclusively.  Sorry.

2. 
   SteveSchoene | Sep 25, 2008 06:51am | #2

   In a well fitted glue joint there should be very little glue to do anything--sanded or planed.  "Jointed" edges can vary quite a bit in how much glue line will result.  So a really tight fitted joint--no light between the boards--will have very little glue line.  And, of course, joints need to be well clamped.  The recommended clamping forces are quite high, so if you aren't clamping down VERY hard, with plenty of clamps you might be underclamping the joint, making for thicker glue lines. 

   With open pore woods, such as walnut, I suppose you also have the factor of glue in pores that aren't possible to clamp away. 

   You could use hide glue, which takes stain and finish, and also has no creep.  It is as strong as, or stronger than, PVA. 

    

3. 
   ring | Sep 25, 2008 07:55am | #3

   Bill,

   I recognize this phenomenon also, and I can't say that I understand exactly what's going on. It appears most often in walnut, and I really suspect that it's just an optical effect of the endgrain contrasting strongly with the glueline when that first coat of finish hits it. If it were a result of sanding it wouldn't be limited to the endgrain.

   So while I'm not sure about the cause, I can tell you one way to get around it. Add a few drops of water-soluble dark brown color (like what's sold for tinting lacquers) to your Titebond before you use it. This is a trick that I've learned from gluing up dark veneers in porous woods like wenge. We tint the adhesive to approximate the final shade. Those few drops in the glue will apparently not affect its performance, and you won't see any gluelines.

   David Ring

   http://www.touchwood.co.il/?id=1&lang=e

1. 
   philip | Sep 25, 2008 08:47am | #4

   "Add a few drops of water-soluble dark brown color (like what's sold for tinting lacquers) to your Titebond before you use it".
   Yah Ring, he could do that or try another glue....
   Despite what you have said*, looking at the chair seat, it looks horribly like there is either some timber drying movement going on -the ends opening, or the boards were not well jointed . If they came straight off a jointer without a touch of hand shooting..... Another good reason to always hand shoot to get a spring joint and be sure of eliminating any mis-use of machinery (;). (Not allowed to say "snipe" here).
   *I have only used a little American walnut-and didn't have that problem, but the pva glue was not TiteBond since it was not available anyway.Philip Marcou

1. 
   ring | Sep 25, 2008 10:41am | #5

   It's impossible for me to make out from his photos if there's any of the dreaded nemesis at work here ("Snipe! Snipe!") but I'm assuming that Bill is observant enough to have picked up on it if it was anywhere in the neighborhood. Could be as you suggest that the jointing was perfectly done and that the walnut has subsequently dried further, starting at the ends which were not yet sealed. Whatever the case, while his investigations continue I'd tint the glue and move on. Maybe the root cause will become apparent one day, maybe it won't...regards,David Ring

   http://www.touchwood.co.il/?id=1&lang=e

1. 
   Lindau | Sep 25, 2008 01:50pm | #6

   David, you seem to have understood what's happening more than the others. It is not a problem with the edges being ill prepared or any type of springback. The wood did not dry after the glue up and pull apart. I've done over a hundred of these seats and have the mechanics of it down.

   I know the second picture is a little blurry, but you can see that the glue line disappears after having been rubbed out with steel wool.

    The only thing that I can think of is that during the sanding, ROS, that the glue is heated enough to smear slightly, and like you said the end grain being porous is absorbing some of the smear. But if this was the case, then rubbing out the first coat wouldn't remove the glue from the pores.  The chair looks great now and is on it's way to the new owner. I'm including one of the last shots I made of it. Thanks for your relpy. I'll try your suggestion of the adding color to the glue. Bill

   
4. 
   flairwoodworks | Sep 26, 2008 08:38am | #7

   I would guess that it has to do with either the fit of the joint before glue up (should be absolutely no gaps) or not enough clamping time or pressure.  By the way, the seat looks otherwise very good.  Be sure to post pictures when it's done!

   Chris @ www.flairwoodwork.spaces.live.com

    - Success is not the key to happines.  Happiness is the key to success.  If you love what you are doing, you will be successful. - Albert Schweitzer

1. 
   Lindau | Sep 26, 2008 02:09pm | #8

   there are no gaps