Veneer Layer in Segmented Bowl Turning Grey After Gluing

Feb 07, 2006 24 Replies
G

Tom,

Actually, you were quite clear, I simply exhibited the far too common Usenet trait of not paying complete attention to what you said. It's been a really bad week...

I have seen what you describe... Similar to this fine bowl by Kevin Neeley, I assume:

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I have never tried it, and don't have any big dried blanks to work with. That is one advantage of turning kiln fried woods. They are already at a consistent moisture content, ergo the parts that make up the bowl segments are also consistent. This ensures that expansion/contraction should relatively predictable, and that (hopefully) nothing should crack after a few seasons. Turning a block of green wood and then trying to glue up with kiln fried segments would require a considerable amount of time for drying and equalization, or as the green blank dried, the segments would pop off like a '69 Ford LTD hubcap.

I've never seen a 10" x 10" x 4" kiln fried butternut blank for sale, and at the price of wood these days, I'm not sure I want to. Same with Cherry, Maple, etc. When I turn large monolithic blanks, I generally use green wood collected myself. Being relatively poor, it's generally a requirement. :-|

As demonstrated by the above referenced bowl, not goofy at all. Expensive and time consuming perhaps, but looks good to me.

With dried woods and MC equalization, it should be doable, albeit at a price. I still worry about the differing expansion characteristics of the various parts. The large monolithic blank would expand greatly cross grain in one direction, but the segmented rings would expand to a lesser extent in all directions. I assume you would have to pay particular attention to the expansion percentages of the chosen woods, turn somewhat thin, and it might possibly require the use of veneer layers and a pliable glue to offset the tendency of the pieces to crack apart at the glue lines.

I'm certainly no expert, but that's my take on it all...

FWIW,

Greg G.

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G

Pretty good theory. Although in person the spots look more like black ink that mold stains. Mold is something we have all too much of here in the humid south, and I've seen a lot of it. The pattern of spots does look like mold, but I'm not entirely sold.

It turns out that there are some odd salts in/on the makore, crystals of it are visible in the grain. I am becoming more convinced that it is a chemical reaction, rather than mold. I have some test setups going, as time permits, to determine exactly what this is - for certain. It seems that clamping pressure after gluing is the major contributing factor as to whether the discoloration appears or not.

I tried de-chlorinated aquarium water and could not provoke the growth of mold. I also tried glue by itself, and also could not provoke the growth of mold. But if I clamp with a lot of glue, and the glue squeezes through the makore veneer into the maple veneer, I get spots within 30 minutes - awfully quick for mold - especially in winter.

I hate to throw out 20 sq ft of makore veneer due to this phenomenon.

For me, the jury is still out on this one...

Thanks for the input,

Greg G.

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T

Greg, Hey that's some cool stuff! Glanced at a couple of the images and the bowl you linked is outstanding. The solid section has so much movement it's as if it's segmented, too. What an example of a plain jane bowl SHAPE being treated in such a way as to be a piece of art in large part because of the simple intrinsic beauty of wood. That's not a slight of Neeley because how he brought it all together is marvelous. Thanks for the link.

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Notice what he did on this one. Created the solid effect in the center that I was talking about but used segments. I gotta learn how to do this stuff but using local woods like the cherry and black walnut I've got piled around here. Maybe the beech could be used as the contrast.

TomNie

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G

There are a lot of segmented turners out there, but KN's stuff is more to my taste than most others. I would love to find out where he gets the black palm - but from what I have read, it's a real bear to turn.

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Feature band is unadorned by detail... But it IS segmented.

A very large beech tree fell in a local park a week ago. I've been eyeing it for a way to cut it up and remove it, but they have the path partitioned off. A crew showed up and threw most of it into the wood chipper. ARRGGHH!!! This thing was huge - about 60' tall and 32" in diameter. The 3-4' sections they cut it into are too heavy to lift.

What a waste...

Greg G.

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