Dissimilar materials and other thoughts

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Fred in NC

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Some things that have happened to me:

Made a laminated pen using dark veneer for the lamination. The pen did not sell last year. I recently looked at the pen, and there was color from the dark veneer bleeding into the light maple barrell. I suspect the dark veneer whas "color enhanced" with dyes, and the dye bled into the sorrounding wood. I used yellow glue for the lamination. I think epoxy would have prevented this.

Another laminated pen, turned real smooth ... months later I could feel the lamination due to uneven shrinkage. I think the change in grain direction in the wood was the cause. Wood does not shrink the same lenghtwise as across the grain.

The band of one of my american flattops came loose. It looks like the wood shrunk, and the glue did not expand to hold it in place.

Different woods might have a different humidity contents, and for that reason will not shrink the same.

My point is that not all materials behave the same. What looks good right away might not hold up later.

I have no experience whatsoever using plastic for laminations. However, since some of these materials are vynil based, I wonder how they will stand up with time. Like the wood shrinking more than the plastic, or the glue not holding up.

I am fairly new at this, kind of a newbie myself, so I hope I am not offending more experienced penmakers. I just wanted to pass along some of my bad experiences in case they can help others.

Any laminated pens, or those with more than one wood, etc., that I make for next year will be handled differently. I am planning to turn the barrels and sand to 400, and then put on the sealer. Then I will put them aside for 2-3 months. At that time I can take any corrective action, and finish the pens.

Happy penturning!
 
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To add to what you have set out here. Veneer is very thin, water base glue will cause it to change dimensions before the glue sets up. That same glue on the pen blank will not effect the dimension the same way because of the mass of wood, there will be a slight change but not as noticeable as on the veneer. So you glue both together, when the water finds it's way out the veneer is going to shrink back to it's original dimension and the pen blank won't go there. The solidified glue is forgiving enough to accommodate the difference in dimension but you will be able to feel it.

One option may be to glue up the construction and let it sit for a week or two to allow all the water from the glue to leave and the wood find out where it is going to settle down. Then turn it. You see this same issue with biscuit joiners. If you glue up a table top with biscuits in the joints and sand it immediately, two weeks later you will see little football shape depressions on your nice flat table top. It is caused by the water in the glue swelling up the boards right where the biscuits are, you sand and then the wood shrinks back to where it belongs and it leaves a depression.
 

tipusnr

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I hadn't considered any of these factors yet. Thanks for presenting them so I can either plan or watch for them. It will obviously make my experimenting more fun as I AM goal oriented.
 

Fred in NC

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Oh yes! I have heard reports about that. Everything from joints that you can barely see or feel to complete disasters. Thinner bowls, because the glue joint is small, could be worse.

The one that made me think a lot is a funeral urn that I saw in a recent AAW magazine. It had a segmented portion, and it looked very thin. I wonder how long it will be before it falls apart.
 

low_48

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Segmented bowls do have problems with feeling the glue line and segments over time if they use yellow glue. I have been to a couple of classes on veneering. The instructor had a slab of yellow glue that he layed out on glass and let dry. He put that rigid slab of glue under a heating pad and warmed it up. When it came out it was limp as a noodle. That is his demo to let you know that yellow glue will move. That's why it works so well with wood. It moves with the wood as it moves. He only recommends urea formaldahyde glue for veneer work. It has a rigid glue line that will not creep.
 

Daniel

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I tis true that wood does not expand or shrink at the same rate across the grain, with the grain, or in it's third dimention. one wood species will also expend at differnt rates than others. there are combinations of wood that work better than others due to these expansion ratios. also stabalization of the wood will take this largely out of the equation but also the thicknesses of woods we are dealing with goes a long way toward eliminating the problem, but it doesn't take much movment to ruin a joint. I would tend toward, stabalized wood and a ridgid glue to keep things tidy.
 
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