Stacked Veneer Experiment with a Shocking Lesson

You’re probably aware that I like to incorporate a twist in my designs.

For some time, I’ve had this idea to laminate a stack of veneer in a twisted manner, so each subsequent piece of veneer is rotated just a degree or two. I suspected that, due to the difference in appearance between long grain and end grain, I would see a gradual lightness/darkness shift along the surface.

To test my theory and see what it would really look like, I cut cherry veneer into 2-3/4 inch squares with my bandsaw, because is was the quickest and easiest way I knew. I chose cherry because of the marked difference in darkness between its long grain and end grain, for better contrast.

I also grabbed two Quick Grip XL clamps, a bottle of Titebond Extend wood glue and prepared some small pieces of melamine as cauls to permit even distribution of clamping force and help ensure the faces stay flat.

Working efficiently and methodically, I spread glue on one face of a piece of veneer and placed another piece of veneer on it, rotated one veneer thickness counter-clockwise. I repeated the process for about a dozen pieces, then put the assembly between cauls and clamped them tightly. I glued together another dozen, then glued it to the previous dozen and put everything back in the clamps, continuing until I had two stacks each about 1″ high. The whole process took about an hour.

After a full day of drying, I unclamped the twisted veneer stacks and trimmed the uneven edges. The yield wasn’t particularly high, so I didn’t have many options for a finished product. I did have some pen kits on hand, so I decided to make a pen with the veneer. I cut one stack into 5/8″ squares, then glued them together, again rotated the thickness of one veneer.

I built a mini router jig to true up the pen blanks then drilled out the centres and mounted them on the lathe.

Once that dried, I made the pen. As I neared completion, I noticed some darker rings in the wood. They puzzled me, and I wondered if I had somehow put some veneer pieces in indirectly. Anyhow, I finished the pen and this is the result.

The twisted design I had attempted to produce was evident, and even more pronounced when I applied a thin coat of oil-based polyurethane to accentuate the long grain/end grain difference. But those rings!

After carrying the pen around for a few days, it struck me that the dark lines were caused when I put a dozen pieces of veneer in clamps to work on another stack, then glued them together! Somehow, this resulted in a darker veneer. How? Did the PVA glue absorb more into these pieces?

To avoid those dark laminations, I may have to glue all the veneers together in one shot before the glue starts to set. A glue with a longer open time would definitely be an asset. Or maybe a different glue, such as a plastic resin or epoxy would work. Or maybe if I just soaked the veneer in water first, the PVA glue would dry more slowly and encourage equal penetration.

If somebody can offer an insight as to why this happens, or if you have your own theory on how to prevent it, I’d love to hear it.

2 thoughts on “Stacked Veneer Experiment with a Shocking Lesson

  1. The dark rings are caused by exposure to light. Cherry is very susceptible to darkening this way. Your rings probably line up with the top/bottom of each drying stack, only to be magnified when cut and restacked in your process.

    • You’re absolutely right that cherry is very UV sensitive, and I think that the rings do line up with the top/bottom of each drying stack.

      Even though the stacks of veneer went straight from the glue-up station into the cauls and weren’t subject to any more light than the rest of the veneer in this stage, once the glue had set, I think I did leave them in the shop for a short period of time before gluing up the combined stacks

      Thanks for the comment.

      Chris

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