Veneer Flattening

This viewer question comes from Thomas. He writes:

I have never attempted to do thin veneers before, but since I always like to do things over the top, I chose to purchase not just a regular veneer but a yew burl one that has more waves and ripples in it than an elderly fat farm on nudist Wednesday. My plan was to use it as a top for a humidor. That being said, my question is, how do you go about veneering such a complicated surface? Do you have a good method for flattening the burl or does that happen once it’s pressed and glued to the surface? Do you use contact cement? Etc. Got any tips?

And here was my reply: Hey Thomas. I like your taste! In veneer, that is. Not in your choice of nudist colonies. As for the veneer, you should definitely flatten the veneer before gluing. This is an easy enough process that can be done in about a day. First you need to make a veneer flattening solution. Here’s a decent recipe (there are others):
Four parts water, two parts glycerine, one part alcohol, and two parts plastic-resin glue. Mix thoroughly and apply to both sides of the veneer with a brush. Saturate it pretty good. This solution will soften the fibers and allow them to flex. But the glue in the mixture will keep the veneer in whatever position it dries in, so you need to press the veneer flat while it dries. To do this, its a lot like setting up a traditional veneer press. Use two plywood cauls to make a sandwich. Cover the veneer on both sides with fiberglass window screen and place some newspaper between the fiberglass and the cauls. So your sandwich would be: caul, newspaper, screen, veneer, screen, newspaper, caul. Make sense? Then you just need to clamp the two cauls together and let it sit overnight. Change the newspaper and let it sit for another 12 hours. If the temperature is cooperating, the veneer should dry within a day or so. If not, keep it pressed and keep changing the paper as needed. Once dry, it will be nice and flat and it will stay flat. But remember, the embedded glue will inhibit the absorption of stain, so only do this technique with pieces you dont plan on staining.

As far as gluing goes, my favorite veneer glue is plastic resin glue. I like Unibond 800. You could use contact cement, but there is just something about working with that stuff that I really dont like. I really like a good wood to wood contact when it comes to veneering and using contact cement feels more like adhering the veneer to rubber, then to wood. In the long run, you will be better off with plastic resin glue.

I know there are numerous other flattening solutions out there. I am curious if anyone has one that wont be an issue with staining later. Respond to this post if you do.

Category: Techniques

Comments

  1. I took a seminar with Paul Schurch. He is an unbeliveable veneer artist. The seminar made marquetry and parquetry less scary (I wish he could do something with my mother in-law). Check out http://www.pro-glue.com/. And when you have a moment, check out http://www.schurchwoodwork.com/. If you see his seminar at a woodworking show, go, listen and take notes.

  2. Tim February 27, 2007

    Could you explain a little bit more about plastic resin glue? How does it apply compared to contact? Is it reactive to heat? Will it effect the finish if you are messy like me with glue and get it on the face of the veneer? How well does it work with plastics, or vynl, or any product with a phenolic backing?

  3. Bob Jones February 27, 2007

    Hi Marc
    I was curious if the window screen you mention in this technique will leave a pattern that will need to be sanded out? I haven’t tried it, but I wonder if I need to make sure I include the extra step if I decide to use this process.

    Keep up the great work!
    BJ

  4.  

    Tim,

    The plastic resin glue is my preferred glue for veneering applications. The bond is very rigid. Something like contact cement is a little more flexible and I have found that in some cases the veneer lifts over time. Perhaps from improper technique, but I would rather avoid the stuff just to be safe. The only time I use contact cement is if I am applying veneer to a surface that cant be clamped properly or if I am applying a laminate.
    In general, the plastic resin glues dry better at higher temperatures. I probably wouldnt use it if the temp was below 65-70 degrees. I really only use the stuff for wood to wood applications so you should consult the individual application instructions from the manufacturer to see what materials it will and wont bind to.

    It will inhibit staining, so you should try to avoid getting any on the face of your veneer.

    And as to bob’s question. The screen might leave some marks that would need to be sanded out. But I usually give my veneered panels a nice sanding before applying finish anyway, so whatever marks were there are usually not a problem.

    Thanks guys!!

    marc

  5. Michael February 28, 2007

    Marc,

    I also tried a burl veneer on my first veneer project and had good luck with Super Soft Veneer Softener that I purchased from Joe Woodworker.com. I used an iron on medium heat instead of Marc’s technique to speed things up and had good results. I used a router with a flush trim bit and MDF cauls to edge joint the veneer but the joint line showed a bit after finishing. Any tips on how to get a better result next time?

  6. Tim February 28, 2007

    Thanks for the info I will have to check it out! I work in a custom cabinet shop that only uses contact cement, so it is all I know. There has been times when i have done side projects out side of work where I wish I had a better alternative to contact cement but I ended up using it anyways because that is what I was familiar with. With all the peculiarities of contact cement I manage to do ok with it, but I have been working with it for years so I know all its ticks!

  7.  

    Hey Michael. You can also use your jointer to get a nice straight edge on the veneer. But I dont think the quality of the edge is where your problems lies. I have a specific technique for joining veneer that I should probably do a video on. Its much easier to show than it is to explain. I actually use blue tape stretched across the joint to create a clamping effect. I stitch the tape across the joint ever few inches. Then I put one long strip along the joint. I then flip the veneer over and make an A-frame exposing the edges of the veneer. Then I actually put a little bit of yellow glue across the joint and spread it carefully with my finger.
    Next I put the veneer flat on the table again and put a nice strip of tape along the entire joint. I then either use a piece of wood or my finger nail to burnish the joint and make sure the veneers are not overlapping one another. Let sit for 3-4 hours and you will have two veneer sheets that act as one. This is a good way to ensure the joint never splits. And you should have a perfect seam.

    Hope the quick explanation helps.

    marc

  8. Old Yorkshireman March 4, 2007

    I say folks

    The good ole hide glue is worth a mention. Damp and press the veneer as described, but then work while it is still damp. If the burls seems to be breaking up, or likely to, then apply veneer tape to the top surface, hot hide glue to the work, and apply and press, or use a veneer hammer for flat surfaces.

    Hide glue is of course, water soluble, so if you use a water based stain there is a hope of being able to match in to its surroundings after you’ve applied the veneer.

  9. Doug Alexander February 2, 2012

    I am using a walnut burl veneer to cover some drawer fronts on a huntboard project and really like the idea of adding some plastic resin glue to the flattening mixture. For your solution using Unibond 800, what was the resin/catalyst ratio of the resin added….3:1? 6:1? Also do you find it necessary to use the Unibond blocker to prevent bleed through when you ultimately apply the veneer to the substrate. Thanks for all the great tips.

    •  

      Hey Dough. I am actually not referring to Unibond in this instance. I should have specified that I’m using Weldwood Plastic Resin Glue which is a powder. Since you need to mix it with water to activate, you might even be able to play with the mix to see how many “scoops” to put into the solution. Either way, I would go pretty light since you really only need a little in the mix. If you go with Unibond, I’d go with the catalyst quantity that allows for the longer open time (less catalyst). And I haven’t used any sort of blocker in the past. Could be more of a measure of the woods I’m using and the thickness of the veneer though. Certainly can’t hurt as a preventative measure but it might be worth running a test board to see if it’s necessary.

  10. Doug Alexander February 2, 2012

    Thanks for that clarification. That helpd a lot. Now, off to turn my veneer rumble strip into a smooth roadway.

    • jim March 25, 2013

      hi….i have good luck with a little glycerine mixed with water in a spray bottle. spray both side….with a very slight mist….don’t soak it at all……..put paper between like plane news print piece of plywood…..and add something for weights…….with come out flat as could be overnight……good luck

  11. Marc,

    I have an antique Queen Anne 1720 walnut burr slant top bureau. I had to replace a small section of water damaged walnut burr. Also repaired small places with missing strips of burl. My problem is that the top, of the bureau is noticiably wavy when you view the top of the desk.. from the side. Since the bureau is so old, I don’t want to remove the existing veneer, to flatten. Can I use a veneer softener which will not damage the top, allowing me to apply flat boards, and heavy flat weights to remove ripples? I could supply photographs of the bureau if I had an E-mail address for you. I know about the round veneer punch, but I am reluctant to go that route.

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