I made some rather thick veneer (3/32 to 1/8 thick) and wanted to try out the iron-on method of coating the base and veneer pieces with PVA, letting the coats dry then ironing them on. It took quite a bit of time and heat (cotton setting and about 20 seconds in one place).
The pieces ironed on just fine, but the seam between each piece formed a gap. I tried to just hold one piece against the other, use a clamp to hold one piece against the other, veneer tape to hold one piece against the other. In each case, I had a slight (maybe 5 to 10 mils or so) gap in the seam. I finally used the old “many clamps” method and just glued the last veneer piece to the substrate without heat. That worked just fine. No gaps. I assume that the wood pieces lost moisture when heated and shrank leaving the gap. Does the problem go away if the veneer is very thin, or is there another way to eliminate this gap problem.
Replies
I wonder if overlapping the joint and trimming with a knife would have helped (seems to be a standard procedure). I've done only a little veneering and that's how I handled seams and had no problems. I was using much thinner veneer than used on your project.
I experimented with the iron-down technique with commercial sliced veneer (.025" thick or so). I found exactly the same problem: gaps at the seams. I eventually gave up on the technique. I now use a vacuum press.
Ditto what Jamie said. I've never gotten it to work with regular flitch veneer, although paper backed is fine. Learn to use hot hide glue and you won't have this problem.
Eric,
Most commercial veneer is 1/32" to 1/40" thick and works very well with the "iron down" method.
Veneer 1/16" is about as thick as can be used with the method. Even then, it's hard to control. At 3/32 and more, it's not the method to use.
Rich
Eric, are you glueing the veneer seams together before you are ironing them down? If not, that will make a difference in the final product.
Typically what I do when assembling veneer is to blue tape the back side, veneer tape the show side. After the veneer tape dries, pull the blue tape from the back and fold the joint open over the egde of the bench. Run a very small bead of glue along the open seam, (from the back side) and then close it back up.
Take something like a wooden handle or a large flat screwdriver and "burnish" the seam to really force the glue into the joint. Then cover the entire seam on the back side with more blue tape. After the glue is set remove the blue tape and you should be able to press the veneer. I usually use a vacuum bag, but this should work with the iron on technique also.
I would probably use thinner veneer too (at least for ironing). 3/64 would be about as thick as I would go if I was sawing my own.
This step may seem like a lot of extra work, but an invisible seam, (especially in lighter woods like maple or cherry) in my mind is worth the effort. Panels will tend to finish better in my experience too.
Peter
www.jpswoodworking.com
I did a version of your method on some of the seams and you are right, it would solve my problem to glue the seams prior to ironing the veneer to the box. I was just hoping that I had found a shortcut since the iron-on method seemed like a way to "tack" everything in place while also creating a permanent bond. The seams that I glued together prior to doing the iron-on method were closed and stayed that way. They were essentially making a solid sheet of veneer.
I could not easily use a vacuum press method easily because of the shape of the box. The old clamp method was less hassel.
Thanks to all for their insights!
Eric
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