Laminating wood question

[mtaylor]

I'm making frame blanks for a Hahn method build using 3/32" thick cherry that's 1" wide.  I edge glue the pieces for both layers and then after that dries, spread a thin layer of wood glue on one blank, put them together and press between two sheets of glass to keep everything straight.  

 

What I'm seeing is sometimes the wood warps and the bond isn't made at the edges.  Is there a cure for this?  Am I doing something wrong?    Just hits me as very strange.

[jud]

After placing the second blank in position on a firm flat surface, use a hammer tap unneeded glue out to the edge, leaving good contact with no voids between the laminates, think laminates are ran between rollers when professionally made to do that. Try to work out from the keel, use a rubber hammer or  a sacrificial block to protect your blanks. A little glue squeezing out is a good indicator of making a good joint, that waste glue will only be on waste wood, just protect your working surface with something like wax paper.

jud

[mtaylor]

I'll try that Jud.   I've been squeezing the blank halves with clamps and then putting them under the glass.  

 

Insanity.. doing the same thing over and over and expecting different results. 

[mtaylor]

I'm also wondering if Elmer's Wood Glue needs to be thinned out for this..  ????

[jud]

When I use Elmer's Glue, white or yellow it has been for larger material such as 2 X 4's, 1/2" and up partial board or ply and use a bunch of clamps which remain in place until the glue dries. I want a little glue to squeeze out of the joints, that bit of glue comes off with a wet rag if the joint needs cleaning up before it sets. I have used a hammer to get the air out of a joint for smaller stuff and if successful the part remains in place long enough to clamp. When using contact cement or construction adhesives the hammer is always used to drive the air out of a joint. Also use the hammer on all leather joints with a contact cement called Barge Cement. Upon reflection on your problem and wanting to obtain the flatness of a glass surface, you might try sandwiching the lamination and the two pieces of glass between some 3/4" or bigger boards and clamp them all together until the glue sets.

jud

[mtaylor]

I tried the "hammer method"... no joy.

 

 

This pic shows the built up frame blanks.

 

This one shows what I'm getting:  The one on the left is what I got from the hammer method.  The one on the right is from last night and slowly coming back.

 

I'll try putting the glue on with my finger and spreading and smoothing with a bit of water this next time.   Seems I'm getting about a 50% good yield on these frames.  I was putting the glue straight from the bottle on the wood and then spreading it.

[jud]

It looks like the moisture in the glue is causing the cellulose in the two faces to expand when looking at the end grain, resulting in the curl. Leaving them clamped until dry may work.

jud

[AntonyUK]

Hi mark.

As Jud has said leave the glue a lot longer to dry clamped.

I have lammanated all the beams on my victory cross section.

Thick PVA glue works best for me.

I have always left the timbers drying for 24 hours.

Not had any warping like you

 

Regards Antony.

[WackoWolf]

Mark,

 

   I did it the same way that Antony did it when I was doing the HMS Warrior and let it sit for at least 24 hours sometime longer, the only problem I had was sometime I broke one but they had never warp for me either. A lot of PVA and time to dry is the trick. Just my 2cents.

[testazyk]

I would agree with Anthony and Wacko--use lots of glue and let it dry--don't worry about excess glue--you can wipe it off with a wet rag.  Clamp the pieces together and also to your work surface if possible to prevent warping.   If you are laminating thinner bits, like for railings or decorative pieces you can also dry them out with a hair dryer to save some time

[Mike Y]

Pardon for a really stupid question, but what is the benefit of glueing together two thin wood sheets instead of using a sheet of double thickness? And it is not a mistake, you ordered the wood milled to that thickness, just trying to understand the method.

[augie]

Looks like the moisture to me.  Longer clamping will definitely help.  I might also consider switching to 1 or 2 hour epoxy if the surface area you need to glue is not tremendous.

[cwboland]

Don't forget to check the end grain of the wood.  Putting the cups together may help eliminate the problem you're getting.  I have used this before for larger projects, ie. furniture and decorative pieces, and it seems to solve the issue nine times out of ten

[bogeygolpher]

Mike,

 

You get significantly more strength by laminating wood in a cross grain fashion than by using a single piece.

 

Mark,

 

I would allow at least 24 hours for the glue to dry.  Probably longer because the glass will not allow for good air circulation to promote drying.

 

Why not use contact cement.  If the wood is not absolutely flat to start with you will need to clamp it, otherwise a j-roller will probably suffice.

Apply contact cement on both sides, allow to dry, place toothpicks or a few layers of paper strips on one of the glued surfaces, place the other side on top (glue side down) and align the pieces.  Start on one end and remove the toothpicks or paper one at a time keeping the pieces aligned while allowing the surfaces to contact each other and bond. Use a J-roller to force any air out from the joint.  It's worked for me doing marquetry.  Don't forget, lots of ventilation.

[Mike Y]

Dave, thanks for explanation! I now carefully re-read related chapter in Hahn's book (ships of american revolution and their models), indeed, frames are double-layered.

Edited April 18, 2014 by Mike Y

[dewalt57]

I've found that the moisture of yellow glue will warp wood but if you use epoxy glue it won't. Try 30 min. epoxy and see if that works.

 

AL 

[mtaylor]

Thanks for the responses.  I think I've got it sorted out:  1) Squirt a pile of glue on wax paper... (this part is now added) go have a cup of coffee and a smoke.  2) Spread the glue as thin as I can on one blank.  3) Put together and squish them.  4)  Clamp between two 1/4" thick pieces of glass with clamps.  5) Go fiddle with something else for a couple of hours.

 

I was using an old bottle of glue until it ran out and when I started the new bottle is when the problem occurred.   Step 1) second part... wait is what I added and seems to be working.

[LFrankCPA]

I hope I am not coming into the conversation too late. What I do is to apply the PVA glue with my finger and actually rub it into the wood. It seems to fill all the little nicks and crannies; hold for a few minutes then clamp it overnight. Spread the glue with your finger to the outer edge of one piece then add and hold the other. Works for me....

Larry