Finish Causing Ripples in Veneer
Troubleshooting a bad interaction between finish formulas and veneer adhesives. May 18, 2009
Question
We use paperback veneer or a thicker version of the same on some gable ends. We spray solvent based contact cement on both the veneer and the melamine or pre finished ply gable. For some reason after we spray a stain or a solid color finish (Matador) the veneer is rippled through the length of the finished side. I have talked to one supplier and he suggested I stop using solvent based and go to water based contact cement. My spray gun method is not fantastic but I do not believe that is where my trouble arises. I am planning on using a roller to do the water based application - any thoughts?
Forum Responses
(Adhesive Forum)
From contributor E:
Use an unfinished ply or a one-sided melamine and lay up the gable ends on the raw side in a press using a PVA or PPR adhesive. The type of press can be a cold or hot or vacuum. Whichever it is, the problem will mysteriously disappear. There may well be a cost or efficiency concern to this change for you, but the cost of failure or the repair work is much greater. The cause is moisture and/or solvent action and the story is long and the punch line may not be worth the wait.
From Gene Wengert, forum technical advisor:
Sounds to me like the veneer has some stress in it that is released with the solvent. A water-based may do the same. Is this veneer highly figured?
From the original questioner:
Not really - maple or alder and some cherry. What seems strange to me is the fact that I have done this in the past rolling on water based with results that are better than the solvent based sprayed on. We do dado construction so we staple or screw boxes together and then apply the necessary skins. A vacuum press does not look like a viable alternative.
From contributor R:
The easiest solution is to use a phenolic backed veneer or a wood on wood veneer. The easiest would be the phenolic backed but wood on wood will also work if you roll the crap out of it. Paperbacked veneer is best hot or cold pressed.
From contributor M:
Cedan makes a thicker paperback veneer comparable to the phenolic back except it has a beige back on it to get away from the dark line caused by the phenolic backer on light colored veneers such as maple. I always cold press my paperback veneers, then you don't have to worry.
From the original questioner:
I think we will try a combination of a wood on wood veneer and also switch to a 3M spray glue – it’s very impressive.
From contributor P:
I have used paper backed veneer. You can use contact adhesive but make sure it’s sticky on both sides. You can also use PVA but you will have to put it in a press or else there will be rippling. I messed up one of my friend’s desks by not putting it into a press.
From contributor F:
I just solved this problem in our shop. The solvent based finish was dissolving the contact cement through the veneer and yes, the backing. Most contact cements are terrible choices for wood veneers of any type besides the phenolic backed type. Found a product called Titan. It is water based, no odor, water resistant when dry (for when we change over to water based finishes) and solvent resistant as well. It has incredible adhesion and invisible glue line. I got it from a veneer supply site online and used it on walnut, maple and ash with incredible results. It works so well we usually just use a "fid" to work it on and bypass the pinch roller altogether.
