Repairing Veneer

B

bbaker143143

Active member
I have veneered and installed several crotch walnut panels in our family room using Unibond 800 as the veneer adhesive to plywood. Winter came and the humidifiers broke. One of the panels has dried out and the veneer has split and separated from the panel in numerous locations. The raised veneer is very brittle as it is dry and has a clear lacquer finish. Repairing the panel using Unibond 800 would require bagging or clamping for several hours which is impossible since the panel is secured to the wall. I attempted hot hide glue which did not hold. Any ideas would be appreciated.  Thanks

Bob Baker
 
Hi Bob -  The only way I can think of to even attempt a repair would be to try to duplicate the basic process of hammer veneering - where the veneer is pressed into a layer of cooling hide glue with a veneer hammer, with a particular technique, until the veneer sticks; as the glue continues to cool the excess glue is pressed out with the hammer, so that eventually the veneer sits flat and stable on the ground of the panel. With your situation you would have to carefully control the amount of glue, the temperature, and how you use the hammer - and also put up with glue all over your finished surface. It might be doable, I'd read up on the technique and practice a bit before attempting it.

Another approach is to use yellow glue and an iron; freshly dried yellow glue can be reactivated by an iron on the wool or cotton setting. If you coat both the ground and the lifted veneer (on the mating surfaces), wait until they are just not sticky to the touch - 20 mins or so - and quickly (and deftly, I'm afraid) press down with the iron you will probably get them to stick. Of course you will also melt your lacquer....but that can be refinished.

I'm not familiar with Unibond 800, so I don't know how that will react to heat, so provide ventilation if you can...and of course try to get the mating surfaces as clean and smooth as possible. Is it lifted over a large area? You might also be able to use cyano-acrylic glue, press down and spray the accelerator at the same time; a little chancy, there, timing will be of the essence. Whatever you try, practice!! on scraps until you feel comfortable.

Hope any of that helps -

Dave Hormel
 
Hi Bob,
Sorry to hear about the veneer and will add some thoughts to the discussion.  When we
used Unibond 800 for laminating, I agree that it took a good 24 hours in a vacuum bag to insure
success, and in some cases folks had issues with it holding, as it often did not flex as needed in
adverse climates.  

In boatbuilding and yacht interiors, the answer is Epoxy.  It sticks whether wet or dry, meaning climate
conditions rarely affect it's bonding power.  I use West System Epoxy resin #105 and fast setting hardener.  
These can be found at Jamestown Distributors, or other boat repair outlets. West System also has a
Epoxy Adhesive that comes in a caulking style tube, with a long thin mixing applicator attached, as do other companies like 3M.  You could also try 1:1 Epoxy at the Big Box Stores, but the West System is 5:1,
meaning that the setting time is slower, but the hardener is stronger.  Once you get it in the crack, place
plastic wrap over the mend and try to apply a levered weight to hold against the wall and keep pressure on
the repair.  5-minute epoxy will repair small cracks, but quality epoxy takes time to set, usually 4-8 hours.
Clean up is done using Acetone, or Distilled Vinegar.  When dry, pull the plastic wrap away, epoxy does not
stick to plastic wrap or clear wrapping tape.  You will have to repair your laquer finish, but by cleaning the
surrounding surface where the epoxy was injected, and a quick clean after the first squeeze out, the bad spots
should be minimal.

Hope this helps,

Mo Yarborough
 
Bob,

After thinking some about your veneer issue, and my suggestion of using epoxy; let me add some further details.

When using epoxy for gluing laminates or veneer, it is important to use a filler as an adhesion bonding material.  West System's answer is Colloidial Silica.  They also use Microfibers, but the silica mixed into the epoxy creates a secure bond.  The caulk gun epoxy adhesive tubes that mixes in the narrow snout on it's way to the repair has a filler to make the appropriate bond.  This is the most inexpensive way to go using professional epoxy for repairs.

My background is in Stage Production for theatre and corporate shows.  We used epoxy for all our construction.  It is used in all Cold-Molded Boat construction and modern yacht interiors for laminating veneer in cabins and state rooms.
Here is an example of an award by Jarrett Bay Boatworks of Beaufort, NC using West System Epoxy Resin and #207 hardner for a finish.  http://www.jarrettbay.com/2013/08/jarrett-bay-wins-prestigious-woodworking-award/

When I was listening to Steve Latta at the Williamsburg Symposium explaning details of the sideboard he was demonstrating, someone asked if he used Hide Glue on the curved doors...his answer was no, he used Resin.  No
one went further with questions, so as a new attendee I wondered if he meant he was using epoxy resin to glue
the veneer to the curved doors.  I would guess that he is..it's a fabulous adhesive.  I use it in restaurant interiors.

Hoping this helps!

Mo Yarborough
 
Mo, Don't know if you remember me but I sat next to you at the banquet in wmsbg. Did you work on the yacht interior? beautiful work. For the above question I have only used hide glue for veneering and I don't think it will work as an afterthought on your panels. Never used epoxy but looks like it would make a great fix for the situation.
 
Hi Kerry,

I do remember you!  What a great time in Williamsburg and wishing I was still there for a while longer!

The yacht interior I shared..no, I did not work on that.  I do keep up with that industry however for the technology in veneer, adhesives, and substrate materials.  When doing commercial or residential paneling or built-ins these things are good to know.  Epoxy resin is great to work with.  It's a little intimidating at first, but the more you learn about it, the more you will see the benefit in certain applications.  You would not want to use it on furniture joints that may need to be taken apart 100 years from now for a repair, but for a set of beautiful teak outdoor chairs...epoxy is the ticket!

The cracked and lifting veneer on the plywood panels that Bob is experiencing can be fixed using epoxy, but
some care needs to be taken doing a short learning curve about epoxy.  It can be a skin irritant in it's curing stage, so you want to wait to sand the excess on the repair surface after it is fully cured, about 24 hours.  Once completely cured epoxy is inert and non-toxic to the skin, but wear a dust mask.

Epoxy works great in vacuum bagging for wood lamination and veneers of all types.  Unlike hide glue that can be hammer pressed, epoxy must have constant pressure until cured, especially on vertical and overhead surfaces, and contoured surfaces.  On horizontal flat surfaces, often just weighted constant pressure will work in lieu of vacuum bagging.  

Good meeting you Kerry!

Mo Yarborough
 
While I would be a bit leery of anything sticking to the Unibond the epoxy may work. As to clamping, how far away is the opposite wall? Maybe you could wedge some long sticks between the two.
 
Unibond 800 is a great glue and should not fail just because a humidifier didnt work.  If your veneer is lifting, you didnt press it correctly.  I have used it extensively for furniture and never had issues.  Often times getting two presses in a day depending on temp..

As far as the repair of the issues now, I would lean toward epoxy. 
 
I have bonded veneer with West epoxy, and had great success. However, be aware that the epoxy will likely penetrate the veneer where it is porous or there are tiny checks or cracks, and may actually soak through and affect the coloration of the surface of the veneer as if it were coated with a clear finish. I was always able to sand it off and return to the look of bare wood, but this was on flat parts made in a veneer press that sanded easily.

Karl
 
Thanks guys, you've given me a lot of food for thought. Unbond 800 is an wonderful epoxy. I used it because the water based veneer glue that I used first made the crotch areas of the veneer expand and swell so much the veneer was impossible to flatten. Using the epoxy and a lever attached to the ceiling should give me enough pressure to hold the veneer down until the epoxy sets.
Thanks

Bob Baker
 
In the past I have had trouble w/ crotch and burl veneers being very porous and "transparent" to glue at some places. This is because the glue soaks through all the end grain in the figured portions. I have found sizing the veneer helps tremendously w/ the "bleed through" of the glue, since the sizing clogs up the pours.

The sizing (for me anyway) works less well when working w/ hot hide glue though, since the fresh glue melts the sizing when I don't move fast enough. But that shouldn't be a problem if you are using a glue for the sizing that catalyzes and sets completely.

Just a thought for next time.

JB
 
I should have taken a picture but your suggestions worked. Screwed a hinged 2x4 from the ceiling and wedged another between the mantle and the lever. Worked like a charm. Used West epoxy on the thin side to go under the lifted veneer. Let it sit over night and beautiful repair. There are some shrinkage gaps but those can be fixed / filled.
Thanks again to everyone.

Bob Baker
 
Bob,  WOW! what a beautiful job you did on your interior!  The West System Epoxy is great, and
if it was good enough for the full restoration of the John F. Kennedy Presidential Yacht interior and
exterior veneer and Brightwork...there was confidence that your repair would be successful, and with
the hope that the repair will last a lifetime.  Thanks for sharing your beautiful work!!
Mo
 
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