Veneer Bubbles - Contact Cement

[Michael Oliva]

I need a little help. I recently veneered a buffet using contact cement (WeldWood Original) and backed wood veneer per the instructions provided by MacBeth Hardwood in San Francisco. Everything seemed to go really well (i.e. no bubbles or difficulty applying the veneer) until I began the the process for staining with water based stain. Per the General Finishes instructions, I sanded everything and wet the entire project with a damp cloth (i.e. water) and was going to resand lightly before applying the water based stain. However, a couple hours after everything dried, there were numerous bubbles on many of the veneered surfaces but not all. I made small slits in many of the bubbles in preparation to attempt some kind of repair. However, hours later almost all of the bubble were gone. I've asked numerous shops how best to proceed and received mixed advise but nothing definitive. So any suggestions are greatly appreciated.

Can I switch to an oil based stain or will the bubbles return?

Can I repair the bubble by injecting a little contact cement or super glue into each bubble (one shop's suggestions).

Can I use an iron to reactive the contact cement?

Or do I just need to re-veneer the entire project?

Thanks in advance!

[Chris Padilla]

This doesn't help you but NEVER EVER EVER use contact cement to adhere veneer...NEVAH!!! :) It works decent with Formica...but not real wood veneer.

I'm not sure how you could repair it. I don't know how contact cement will react with any other types of glue you might use. In other words, with all that contact cement already there, would PVA (white/yellow wood glue) or poly (Gorilla) or cyanocrelate (super glue) stick to it? Epoxy might work but it could be difficult to inject into the slits cleanly. Epoxy tends to stick to everything (that can be good and bad).

You cannot "reactivate" contact cement...it doesn't work that way.

If you want to redo the veneer, do you have access to a vacuum bag? That is the best way to veneer IMO...especially large projects like a buffet table. How big is it anyway? Glance at my Tansu (http://www.sawmillcreek.org/showthread.php?t=92396) project to see how I veneered and used a vacuum bag. I'm also local. :)

[Chip Lindley]

This doesn't help you but NEVER EVER EVER use contact cement to adhere veneer...NEVAH!!! :) It works decent with Formica...but not real wood veneer.

You cannot "reactivate" contact cement...it doesn't work that way.


I beg to differ with Mike on the use of solvent-based contact cement with real wood veneer. It WILL work, if enough is used. At least two thorough coats should be applied to BOTH surfaces before adhering. It does work because I have refaced whole kitchens with WeldWood solvent-basedthis way, with NO call-backs.

In a sense, heat will reactivate contact cement. Sufficient heat will soften the rubber and allow it to flow a bit; hopefully rebonding upon cooling. Before applying more glue, you have nothing to loose by heating the veneer with a hot iron. Use the hottest setting, and protect the veneer with an old cotton tee shirt. (no synthetics) After ironing your veneer apply pressure or use a J-roller until it cools.

But, I fear that your veneer/substrate is starved for adhesive, causing the bubbles from lack of adhesion. Insufficient contact cement was used to bond the two together. Otherwise, the bond would be eternal!

If ironing does not help, on to Plan B. Rather than trying to glue down numerous bubbles, removing the veneer and re-gluing may be best. Invest in a heat gun and a broad putty knife, and you may be able to remove the veneer sheet in one piece, to use it again! I guarantee, if two thorough coats of contact cement are applied to both surfaces, with a third coat around all perimeters, it will stick!

[Mike Henderson]

Yep, contact cement on raw wood veneer usually doesn't work very well for the reasons you now know. If the veneer is paper backed you can use contact cement, but even then I prefer to use some other glue.

I don't know any way to fix it either. You're probably going to have to strip (or sand) the old veneer off and re-apply with a regular wood glue.

Mike

[Josiah Bartlett]

You may be able to avoid further bubbling while finishing the project by putting on a sealing coat of shellac or lacquer and using a surface based stain for the finish, but you may not get the results you want. The piece may eventually fail just due to environmental variations.

It probably bubbled because the moisture from the finish expanded the veneer more than the base and the contact cement couldn't hold it.

[Steve Hayles]

Sorry to say but at the risk of it happening again and the time plus possible cost. Safest option is your option #4 Re-do-it. I'm a firm believer in Hide Glue. Even over PVA's it is so forgiving!


Cheers


Steve

[Steve Rowe]

I'm with Chris and several others on this. I have used contact cement on veneer before with seemingly good results for a while. As time passes, it gives way and leaves ugly bubbles and there isn't much you can do about it. I will never ever use contact cement on veneer again. This is a lesson I learned the hard way.

[Gerry Grzadzinski]

Contact cement is not the best adhesive for veneer. Using a water based finish compounds the problem, because the water caused the veneer to expand and contract, loosening the contact cement bond.

However, it is possible to get good (decent?) results.

Ideally, you want to spray the contact cement. If sprayed, you want at least 2 light, very even coats. If rolling, I'd use at least 4 coats.

The glue must be thoroughly dry before applying the veneer. Lay the back of your forearm in it, and the hair on your arms should not stick to it. If they do, it's not dry enough.

Once applied, you need to apply a LOT of pressure to get the best bond. Best thing is the edge of a wooden block, 2-3" wide, with a 1/8" radius on the edge. Make sure the corners are rounded, or you'll gouge the veneer.

Any water based finishes should be allowed to dry for at least a day between coats, including stains and dyes.

More info here.
http://www.oakwoodveneer.com/tips/hints.html