Book match grain question

[Phil Mueller]

I resawed this piece of Koa, jointed it, glued it up and am in the process of flatteing it. The far end of the board is near perfect to my eye with mirrored grain. The bottom half, though, where there is some nice figure almost looks like it didn't come from the same board...nearly opposite coloration. Really makes the glue line stand out. Hadn't noticed it when it was somewhat rough, but planing sure brought it out.

Is this normal for figured wood?

Thanks.
Phil


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[Jim Belair]

Chatoyance. The result of light on the differing grain direction and more noticeable in figured wood since it has widely varying grain.

[Brian Holcombe]

Phil, it's unfortunate but book matched grain runs the opposite direction so it always shows.

[Warren Mickley]

Some people think you are nuts when you try to explain this phenomenon to them. You give an excellent illustration here, Phil.

The effect is toned down with sanding and some kinds of staining, but then the liveliness of the wood is lost also.

[Prashun Patel]

Phil-
You did a great job planing! It's not only chatoyance. In fact, with time and dulling of the finish, the disparity in the light reflection of each half tends to diminish.

It is more the contrasting grain direction that accentuates the line - as in the bottom of your picture.

It's always a judgment call with grain matching. Had you flipped the boards, you may have had more consistent light reflection, but you may not have liked having that arcing grain in 2 places.

A lot of people deride book matches, but each situation is different. I think your orientation is fine.

[Warren Mickley]

Phil-
You did a great job planing! It's not only chatoyance. In fact, with time and dulling of the finish, the disparity in the light reflection of each half tends to diminish.

It is more the contrasting grain direction that accentuates the line - as in the bottom of your picture.

It's always a judgment call with grain matching. Had you flipped the boards, you may have had more consistent light reflection, but you may not have liked having that arcing grain in 2 places.

A lot of people deride book matches, but each situation is different. I think your orientation is fine.

I don't know why you would think the disparity would diminish in time, Prashun. I have a desk that shows very nice chatoyance after 200 years. And things I made 30 and 35 years ago still have these lively qualities. Here is a violin with book matched back from 1716, showing the same phenomenon. The joint is made noticeable by the figure.
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[Prashun Patel]

Warren-
wow. fantastic violin. Do you have other pics of the front? I love eye candy...

I did not mean the chatoyance or the line would disappear with time. I meant disparity in light reflection diminishes over time. I can't explain it or back it up with more than a handful of anecdotal pieces in my house. Perhaps my eye just gets used to furniture in a fixed position. Does your violin back reflect light unevenly in raking light? The straight on shot does not show such disparity between the 2 halves.

[Malcolm McLeod]

A little late in this case, but for next time (maybe). If the effect is murdering your design, you could try a slip match.

[george wilson]

Spruce guitar tops also show a great difference in light if the wood is not cut parallel to the grain in the tree. And,some trees grow twisted,so nearly impossible. I have some W. Va. red spruce like that. Too rare not to use. It was the wood of OLD,prized Martin and Gibson guitars.

[Warren Mickley]

I picked a violin to show because they were routinely book matched three centuries ago and there are lots of pictures available. If you rotate the violin the dark areas become light and the light become dark. Likewise in Phil's board, if he rotated the board the light part on the right would become dark, the part on the left would change to light.

Here is another violin that perhaps illustrates more clearly. On the upper part of the violin there are some wider bands of light on the left side that correspond to dark bands on the right. And for that upper section, the left is on the whole lighter. Viewing the violin from another angle would change the light to dark and vice versa.

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[Chuck Nickerson]

This is often normal. Some confusion comes from our sloppy use of language. Book-matching gives you mirrored growth rings, not grain.

[Phil Mueller]

Thanks all!

This is my first attempt and frankly just didn't know what to expect. Part of the surprise working with wood I guess. And yes, Warren, you are correct that light and dark sides change depending on the light direction.

Would prefer it to be consistent down the entire piece like the violin. It's just the top vs the bottom strikes me a bit odd. Oh well, committed now, so we'll see how it all comes together.

[Warren Mickley]

I think that part of the reason it is so noticeable is that you have done a good job of planing, which brings out the figure. If you took a board with some figure and planed it all one direction, then took one swipe down the middle going the other direction, you would also see some reverse shading. Or if you had a very wide panel and planed just the near side then turned the board around to plane what had been the far side, it would be easier planing, but would give a weird effect. We sometimes do this with a trying plane, but then go all one direction with the smoothing plane at the end.

Choosing stock for a panel like this takes more skill and experience than the actual planing part. We sometimes spend a great deal of time thinking how to cut up our stock for pleasing panels etc. Depending on placement and lighting your panel may look fine or maybe just a little bit odd, but at the very least, you know a bit more what to look for in choosing your boards.

[Phil Mueller]

Oh brother Warren, I'm just starting to get this planing thing figured out and it's suggested now it's too good...😀 Just a friendly jest, of course.

I do appreciate the planing compliments. A good deal of time setting up a few planes, getting a decent camber on an iron, and shaving scraps down to nothing is starting to show some results.

Your comments are well taken; there is obviously a lot of skill and experience in choosing stock. Most everything I've found on this subject is how to set up a band saw for resawing, nothing so far on how to choose wood. If anyone knows a source to get me started, please chime in.

Thanks again to all for your comments.

[george wilson]

The difference in light reflection of book matched halves depends STRICTLY o wether the wood in question is cut EXACTLY WITH the grain,or if the tree had a twist to it, as I have mentioned. If this is the case,you will be looking at the grain going DOWN in one half of a book match,and the grain coming UP in the other.

The only way to avoid this is to use SPLIT wood. If it is split(as in with an axe or a froe),the wood will be at its most parallel in both halves. The best violin tops sold are SPLIT,not SAWN.

[Patrick Chase]

The difference in light reflection of book matched halves depends STRICTLY o wether the wood in question is cut EXACTLY WITH the grain,or if the tree had a twist to it, as I have mentioned. If this is the case,you will be looking at the grain going DOWN in one half of a book match,and the grain coming UP in the other.

The only way to avoid this is to use SPLIT wood. If it is split(as in with an axe or a froe),the wood will be at its most parallel in both halves. The best violin tops sold are SPLIT,not SAWN.

As a cellist this piqued my curiosity: Are those the best cosmetically, or does managing the grain direction that way also help with acoustic properties by ensuring alignment of the grain with the back's long axis?

I'd guess that splitting does both...

[Phil Mueller]

Good to know George, thank you.

[Chris Fournier]

Wood that has been split or riven is superior to sawn wood in instruments and other objects because careful machining afterwards delivers pieces with no grain runout, short grain etc. When book matching I look at the grain of sawn lumber to anticpate problems and once I have chosen the book matched faces I am very careful to do the least amount of stock removal to these faces to ensure the best mirror image in the book matched halves. Not difficult to understand or do once you have put together a few disappointing pieces...