Gluing and finishing veneer

[David King]

Would a steam iron or just a damp cloth over the wood help? Heating wood is always fraught but heating it while keeping the internal moisture constant ought to ease the effects.

[Steve Senseney]

I don't have any personal experience, but I remember seeing something about stitching the veneers together with very thin thread of some kind.

The thread disappears when it is sanded and finished. If you google search for veneer thread stitching, you find machines for sale and other information.

[Clay Schaeffer]

I think the "iron on" method works best with paper or foil backed veneers, especially if they can be put on in one piece. For something as small as a guitar body the face could be veneered using epoxy, waxpaper, and a clamping caul. The down side is that you may get some "bleed through" and need to do an epoxy fill to even things out. This makes staining the wood difficult.

[Mark Parker]

The down side is that you may get some "bleed through" and need to do an epoxy fill to even things out. This makes staining the wood difficult.

How did you get the epoxy fill to 'cancel out' the bleed through? I tried that on some sides I laminated out of curly maple that had pretty severe bleed through. I thought just coating the whole thing in a new layer of epoxy would solve the problem, but it didn't. Bleed through areas are still very noticeable.

[Clay Schaeffer]

A simple method of veneering is to use contact cement or a high strength spray glue (3M spray 90). If you use this method and use a solvent based finish you must mist on the first few coats of finish, then a few light coats, and finally full wet coats. You don't want the solvent to get to the glue. When matching seams you can use a dowel to create the "bubble", but knowing how big a bubble to create only comes with experience.

[Steve Sawyer]

How did you get the epoxy fill to 'cancel out' the bleed through? I tried that on some sides I laminated out of curly maple that had pretty severe bleed through. I thought just coating the whole thing in a new layer of epoxy would solve the problem, but it didn't. Bleed through areas are still very noticeable.

I have done a lot of veneering, and the usual cause of excessive bleed-through is too much adhesive. I use a vacuum bag which makes it even worse, so I've learned to apply the right amount. My current build is veneered with some extremely porous pommele sapele, and even under vacuum, the bleed-through was minimal. You want to get the surface thoroughly and uniformly wetted, but you don't want to see any puddling or big "ridges". An ideal tool for spreading veneer adhesive is a closed-cell foam roller, or a metal "mastic" spreader with a 3/32" tooth pattern.. The mastic spreader is better because it doesn't require any practice to get a perfect amount of glue on the surface. The closed-cell roller works great, but you have to (through experience) develop an "eye" for how much adhesive you have. I use the roller, and shoot for a very translucent film of glue. I do apply a coat of epoxy after the glue has completely cured, just to keep from damaging the veneer in subsequent operations, and then do one or two more coats just prior to finishing to pore-fill.

[Mark Parker]

I thought I was using a very small amount (1 pump of each, resin and hardener, West System did all 4 glue interfaces of my 5 layer laminate schedule), applied with a credit card nearly as thin as I could make it with everything still being 'wet', but the curly maple obviously has alternating side grain/end grain in the curl and the end grain bled through in quite a few places. I think I can rescue it with a couple coats of epoxy on the surface, but I want to be sure I understand your procedure. You apply a total of 2-3 very thin coats of epoxy to pore fill prior to finishing, right? Do you then sand it back until you are getting bare wood? Or just until you have a nice smooth epoxy surface? For a table in the cockpit of my boat, I put down a heavy layer of epoxy and then coated it with varnish for UV protection and that has worked well. Each year I can sand just enough to get a good tooth and apply more varnish. I thought, however, that the idea of pore filling was to fill just the pores and have raw wood to apply the finish to. Epoxy is so hard to sand that I worry that by the time I sand through that, I will also sand through the veneer. How do you do it?
Thanks

[Carl Dickinson]

I don't sand all the way back to bare wood although sometimes it happens anyway. Also my initial coats are not thinned (but they are thin). Just sand until the surface is flat. Then the final coat is thinned and wiped on to cover any sand throughs. Then finish.