Veneering with contact cement
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Is this kosher? October 30, 2002
Question
I just started a new job, and I feel like I'm rocking the boat enough on every other topic, so I'm hesitant to bring up the topic of us using contact cement to adhere paper backed veneer to plywood. I prefer to use urea glue in a cold press... Has anyone had a problem with veneering paperbacked with contact cement?
Forum Responses
From contributor D:
I don't know much about what you are doing with the veneer but I'd suggest that you take it slow about making myriad changes to the operations of your new employer. I don't think going to him with a bunch of "expert" opinions will necessarily help save your job either. Safety issues are the exception, but how he chooses to process his product is probably not in your job description at the present time, or is it?
From contributor R:
You're right. Contact cement is a good product to put down plastic laminate but scary on veneer. I've seen a lot of bubbles in veneer when it's used. Lacquer tends to break down the bond. But if the boss doesn't like input, keep it to yourself.
I've been using 10 mil paper back with waterborne contact cement for about three years now with excellent results. Simple, fast and effective.
From contributor P:
There are two issues here.
1) Type of contact cement. I use 3-m water-base contact cement. It tends to curl veneer products, but I work around that because the lasting bond I get with 3-m is better than any other water-base product I've ever used, and no solvents to rot the brain.
2) How to apply the veneer. I use a 6" drywall knife, round off and polish the edge and corners. After your veneer is set down and located over the substrate, on waxed dowel rods, pull out a couple dowels in the middle. Take the drywall knife and starting from the middle of the piece, drag towards all the edges. Keep pulling dowels as you go. This will press out all the air bubbles as you work toward the edges. All that done, press with a j-roller. Or, if you're doing a tabletop that can't have any tiny high spots at all, put it in a press overnight.
This is not as good as hot press veneering, but you can do stuff like cabinet ends and curves.
We use contact on paper backed without any problems.
I've done quite a bit of veneer work with contact cement. Use a veneer scrape (not a "j" roller) to work out the bubbles, spray on your glue. The only problem I've had is where I had to make a joint in the veneer. After the project was in place for a while, the veneer shrunk and a gap opened up at the joint, leaving a nice red 1/16" gap! From then on I started using yellow glue at any joints for about 1" in either direction and contact cement everywhere else.
From contributor R:
The bubbles form not from trapped air, but the expansion of the veneer on the substrate. I've seen jobs that were ruined this way. Things to look out for: will the painter-finisher be applying high-build finishes with lacquer? Does he/she leave adequate time between coats? Does he/she apply excessively heavy coats? Will there be major swings in temperature or humidity? Do the conditions in your shop closely mimic that of the final install? I have used lots of contact to apply veneer and only had a few small problems, but I've seen my old boss spend $6000.00 on veneer, no labour, to replace a hotel lobby. You guessed it - everything above in spades.
I’ve had more than one bad experience applying 10 mil veneer using contact. This was back in the days when I used melamine interiors and didn’t panelize the finished ends. My solution was to use a phenolic backed veneer and hide the ‘black line” by edgebanding the finished end’s face after assembly.
If you must use contact, I’d toss that J roller. Instead, use a block of hardwood with the corners eased, and apply all the body weight you can. (Consider the difference in pressure generated by a J roller which flattens out to 1/2” versus a wood block at 1/16”. You’re getting 8 times the PSI using the block!)
Now, regarding the “second guessing the boss” issue. Let’s just say that my coworkers 25 years ago used to refer to me as “Mike the idea guy”. That moniker was usually uttered with an accompanying eye roll! The point is that you’re thinking and are passionate in how you approach your job. I think that bodes well for your future. Just try not to overdo it.
From contributor D:
That's a very good point about being a thinker on the job. Don't take my suggestion to mean that you should "keep your mouth shut and just do your work". Even though I take great effort to keep every aspect of my process as simple as possible, there is and always will be room for improvement. My wife (and assistant), who isn't into the complexities of cabinetmaking, occasionally surprises me with a brilliant idea about changing this or that. I end up wondering how it is that I have been doing something the hard way for so long without realizing it.
You must always be thinking ahead and I encourage you to do so. You said that you felt like you were "rocking the boat enough on every other topic". Rocking the boat and making intelligent suggestions are very different. “Rocking the boat,” suggests to me that you are upsetting the workflow on the shop floor and helping to create a breakdown of the team spirit of a good working environment. When it comes to issues that change established procedure, find an appropriate time to make a suggestion to the boss when and where your comments will be somewhat more private than out on the shop floor in front of other workers. That way the boss should feel less threatened and is more likely to give the greatest consideration to your suggestions. Don’t be surprised or discouraged if changes are not made immediately as it is the boss that should have the “big picture” and will know when the time is right to effect changes to established procedure. I've always believed that there is something to be learned by every person in a leadership position. Sometimes the only thing to be learned is how not to do something. Store that in your hard drive for the time when you are in a position to affect others.
I have used contact cement. I have used only the Imperial brand that comes in a propane size canister and spray gun. I hate contact cement in general. But I have to admit, this stuff is pretty slick. The only veneer pieces I have done were finished mockups. I kept most of them over the years outside, in covered storage in Seattle. They show no blemishes or bubbles. I still would use a UF if my name was on the job, though.
From contributor B:
Yes, it can be done, and I've done it many times. However, there are those times. My problems, I believe, were caused when solvents from the finishing process actually got into the paper back and reactivated the contact cement. As was suggested, cold pressing is best, but contact will get you by in a pinch. Just be very careful during the finishing process.
From contributor F:
Get out the tin cans, snow balls and whatever else you may like to throw, because I'm about to tell a truth that many will not like. If you use contact cement to apply wood veneer, you will have a failure! When, not if, you have such a failure, it will not be the veneer that fails. You may enjoy good luck for many years, but, contact cement as an adhesive for paper backed veneer will, sooner or later, fail! Contact cement, when used for a veneer assembly, will cost you a lot of money.
You're right on that contact cement is not the appropriate way. It's also not always solvents in the finish which cause problems. My biggest headache with this came from using water-based acrylic poly over WA 950 glued cherry veneer. The veneer absorbed moisture, expanded (which the non-rigid c.c. allowed) and then checked the finish all over the place as the finish fully cured and the veneer shrank.
As far as how to approach your new boss, do it delicately. Let him know of your participation in these forums and your other sources of information on these issues. Tell him in private. Suggest and inform, don't criticize his methods. Continue doing it in the shop his way unless he gives you specific permission otherwise. And most of all, just keep doing an excellent job. The best way to get his ear is to impress him with your work habits and attention to detail.
I see the problems with veneering with contact cement, but still would appreciate suggestions as to what the best way to apply the veneer is. One or two of you said water-base contact cement - is this the best? I know yellow aliphatic is not as I have tried it and what a mess! Perhaps I should have pressed it? I am nothing more than a beginner with veneers.
From contributor D:
Yeah, I was wondering the same thing...
Aside from many antique repairs when I've used veneer and hot hide glue, I've always used PSA backed veneers and only had to worry about preparing the substrate surface. Started using it about 6 years ago on a kitchen makeover and lately (past few years) to wrap rigid PVC drainpipe to make wood veneer columns. Not a problem, but does take care in placing it without getting trapped air. Can’t imagine using aliphatic resin glue without a means to press or clamp it over its full surface, at least for several minutes till it dries enough to stay tight until it fully cures.
From contributor F:
The explanation is long. The short story is: Contact was invented for laminate. The glue line could be flexible because the laminate is rigid. A mix of rigid and flexible works. For the flexible wood veneer, a rigid glue line works best. PVA provides a rigid glue line but sets slow and can be messy, as suggested. Urea, the preferred veneer adhesive, is also a hard or rigid glue line, but urea requires heat or sets very slow. Enter FSV, a synthetic resin (PVA), cold, fast-setting adhesive that gasses off excess moisture before assembly. Works similar to contact in the way it is applied. Visit the adhesive forum or contact Jeff Pitcher at that location for more info and detail including the info about solvent based finishes attacking solvent-based adhesives.
From contributor R:
You could use laminate backed veneer instead of paper back. It's a little more expensive and leaves a dark line on the edge that you need to tape over, but it's bulletproof. You could also coat both substrate and veneer with PVA glue, then let almost completely dry, then press on. Use an iron to reactivate glue and use a stick to press on. This takes a little trial and error to time it right, but works good on small amounts.
Spraying water over freshly laid veneer is probably not the greatest idea. Every time someone I know uses water based materials, there seems to be some disaster, with the exception of some catalyzed acrylic hardwood flooring coatings I've used.
From contributor P:
I did all the cabinets in my house with paperback veneer on finished ends. Used an oil based stain, then topcoated with a water based finish. I look at it every day - nothing wrong. No bubbles, splits, cracks, nothing.
From contributor B:
Go back and read contributor F's post - he's right.
Most of us in a production environment don't have the time to mess with oil base stains and their drying times. I ain't even going to touch the waterborne finish.
For the occasional radiused end panel or door, I have experienced good results using san ply foil backed veneers with contact cement. The veneer has three layers of backing with a layer of foil in the center that keeps the solvent from the paint from the adhesive. I am not a pro on this but I did the architect's desk that gives me most my work with this product and 10 years later I am still doing his work.
The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).
Comment from contributor A:
I have read all of the comments and am quite sure every one of you is right. I manufacture yacht interiors. Millions of dollars are invested in these elaborate toys and a failure in anything can be disastrous. My research and testing has me applying veneer in only a couple of ways. Extensive vacuum bagging wherever possible with uf109 and where needed, such as a curved wall on the boat or somewhere that leaves no choice but contact, double coat both with waterbase 3m green. Let it dry completely before applying. Use a scraper even if you have to make one to fit odd curves. Leave the joints open for as long as you can. I can usually do this for days or weeks. I realize some jobs don't allow this, but when you glue the joints again, use uf109. Let it kick a bit, 20 minutes or so, then use a medium hot iron and pressure. With little practice it works great - absolutely no failures yet. When it comes down to it, the end user has to be aware how to take care of it. Make them aware what could go wrong.
