Replies

1. 
   woodrae | Mar 21, 2007 05:12am | #1

   Robert—

   Paperbacked veneer is cool; using contact cement ain’t cool.

   Contact cement is too rubbery to confidently hold veneer to any surface, flat or otherwise. Seams and edges are where you’ll usually find the biggest problems, because they’re more likely to peel up or distort. There’s also a real risk your headboard will show little hillocks of unstuck veneer in random spots over time as the adhesive stretches due to miniscule amounts of movement in your veneer or substrate. Besides being too soft to hold veneer without shifting, the glue has a measurable thickness that also impedes adequate bonding, particularly at seams. I suspect your black line is contact cement that got between your seams during glue-up, and which in its soft state was inadvertently filled with sanding crud and other debris from the sanding and smoothing process.

   I know, I know. There are many woodworkers and woodworking companies that recommend using contact cement. It’s a sad state of affairs, and one that’s very confusing and misleading for beginner woodworkers. And it’s been going on a long time. I’m not naming names, but one prominent mail-order company that's been in business since the beginning of the last century (*cough, cough* begins with a ‘C’ *cough* same name as a famous Roman Emperor *cough, cough*) calls one of their adhesives ‘veneer glue,’ even though it’s a form of contact cement. Don't buy this stuff, unless you're covering a countertop with thick, rigid plastic laminte. Seriously. It’s a bad idea to use contact cement and expect it to hold sheets of veneer to a substrate in a satisfactory manner.

   Next time you’re veneering, use a harder glue that goes on much thinner. White and yellow glues are OK for flatwork, but a more reliable and much harder glue, plastic resin, known in the industry as urea formaldehyde, sometimes sold as urea resin, is the adhesive of choice for stressed work, such as curves. You can buy the water/powder variety at your local hardware store, but my favorite is the resin/powder version because you’re not introducing water into the glue-up, which can swell things and, again, play havoc with your seams. Unibond 800 is one brand of resin/powder plastic resin being sold to hobbyists and small shops.

   I fully understand the lure of using contact cement for veneering, since you don’t need a press. Resist the urge, please, and use either shopmade cauls and platens with clamps, or invest in a press, such as a vacuum bag setup.

   Having said all this, you might salvage your curved seams by incorporating a detail that will help hide them, such as routing a narrow, curved channel along the seams (with a 1/16 in. or 1/8 in. router bit) and then inlaying a strip of contrasting veneer, or string inlay, into the groove—using the appropriate glue, of course. Call it a 'learning curve' detail.

   The truth is, your headboard may fare very well for a number of years, especially if you finish it well and look after it in a stable environment. Some day, however, although maybe not in your day, it will become a problem as portions of it start to delaminate.

   —Andy Rae

1. 
   ret | Mar 21, 2007 04:50pm | #2

   Thanks for your reply.I am familiar with water/resin and have used it when gluing up wiggle board and solid lumber but haven't tried it on veneers. next time I will try the resin/resin as well.When I was applying the finish I added a little dye to shade the veneer and now the dark lines look like veins in the grain. It looks pretty good so far .Just hope the seams don't open up.