Maple veneer problem

[Eric Nickerson]

I hope I'm in the correct forum, new here so it seemed like the most likely place. 2 projects I've done in the past week and 1/2 have had this same issue. I have used 20mil paper backed maple veneer over ply to finish a profect, one in a pyramid table base and a table top. The day after the veneer was applied I have found long bubbles under the veneer. After doing the table base it rained the fallowing day and was very humid i fugued that was the problem to day I went in the shop and the table top has bubbles under the venner also. On both of these projects I did not use a vacuum system just the old fasion way, pressure with a 3" wide piece of wood. I live in Georgia so humity is usually high. Any ideas on how to cure or prevent?
Thanks

[Frank Drew]

Eric

What type of glue did you use? Also, I'm not entirely clear on your pressing method (3" wide piece of wood?)

[Alfred Cole]

I have not used a paper backed veneer but I use veneer regularly and I think the problem might be that you have laid your veneer along the same grain line as the plywood ground. It's a problem I ran into in my early attempts at veneering. The wood in the ply and the veneer are possibly expanding and contracting at different rates. I use veneer without paper backing and because the veneer was well bonded to the ground, my veneer split.

I suggest you always lay veneer on a wood ground at right angles to the grain run of the ply ground. In other words you are continuing to make a ply, the veneer is another ply layer.. It is best to do the other side with a cheaper veneer in the same way because the oldest rule in wood finishing is always do the same to each side.

Jerry

War does not decide who is right. War only decides who is left.

[Eric Nickerson]

Eric

What type of glue did you use? Also, I'm not entirely clear on your pressing method (3" wide piece of wood?)

Instead of using a J roller, with wood veneer I use a piece of wood with the edge taken off, you push this along the surface pressing it down the same way. You can apply much more pressure than using a J roller.

I used DAP Weldwood contact cement original

Alfred, The base i veneered was with the grain but the top I just did was opposite.

[David DeCristoforo]

You can "fix" the bubbles with a clothes iron set to high. Iron over the bubbles to soften the contact and use a veneer hammer to press them back down. In the future, when laying up paper backed veneer with contact, use a veneer hammer to press the veneer, not a "J" roller. You need a lot more pressure than you need with P-lam. Also, next time try to get phenolic backed veneer instead of paper backed. It sticks much better with contact.

[Frank Drew]

Like Alfred, I'm not very familiar with backed veneers; with plain veneer, however, contact cement is not recommended, because of just the problem encountered.

[Eric Nickerson]

thanks for the advise David. I didn't use a J roller I used a flat edge piece of wood which would be like using a veneer hammer.
What type of glue should be used with wood veneer? I use 5' wide sheets and have only found it in paper back.

[john bateman]

thanks for the advise David. I didn't use a J roller I used a flat edge piece of wood which would be like using a veneer hammer.
What type of glue should be used with wood veneer? I use 5' wide sheets and have only found it in paper back.

Contact cement is ok on backed veneer...your using it like a laminate. There is a roller specifically made for applying the stuff on large areas. The home centers should have it.

But you must get the cement on in an even coat, and it has to dry completely before assembly. Your high humidity isn't helping, either.

[Frank Drew]

Eric,

With all-wood veneer, most of the glues familiar to cabinetmakers would work well -- white or yellow glue, plastic resin glue, various two part glues formulated for veneers available from some of the equipment suppliers...

For normal, uncomplicated veneering I used white or yellow and never had a problem; if I anticipated a long open time and wanted absolutely no creep (as with a curved lamination) I used brown glue (Weldwood plastic resin.)

To me, the advantage of wood veneer is the selection and quality; unless things have changed substantially since my buying days, the very best veneers are unbacked (except possibly special orders.) Also, and importantly, the actual wood portion of some of the backed veneers can be awfully thin -- look at it wrong and you've sanded through.

[David DeCristoforo]

Try this stuff:

http://www.veneersupplies.com/product_info.php?products_id=59

It's the weirdest glue I've ever used but it works great. It is applied to both surfaces and allowed to dry like contact but then ironed down kind of like with hide glue. But it forms a "hard" glue line and I have never had bubbling problems with it either with backed or "raw" veneer.

[Eric Nickerson]

I will try that glue next time I have to use a paper backed veneer. I normally use wood on wood but 5' wide sheets only came with paper back (bubble free) I ironed the entire area and repressed the surface area this morning. After sitting for the day all seems to be holding well. I will finish work on it tomorrow. Thanks to all