Bookmatching

[WoodyMcKenzie]

When I look at bookmatched backs of both mandolins and violins, the flames or horizontal figure often don't appear as mirror images of each other. This makes me wonder if it matters whether bookmatching is necessary. Why can't I take a 6 inch board (that is much more available) and then join two successive lengths of it, as long as the grain along the entire length is very similar? Is this called a slip joint?

Thanks!

Woody

[KenR]

Yes. I'm not a builder but I believe this is called slip matching. Most of the Loar backs were done this way as are most Gilchrist mandolins. It's difficult to get enough highly figured wood off one log for book matching because of the way it's cut. Slip matching makes for more efficient use of the wood while maximizing figure. - Ken

[Jim Hilburn]

Woody, I expect that every back you've seen was perfectly bookmatched. When you cut through curly maple, you don't get a mirror image, you get a positive-negative image. It's much like looking at a waveform in electronics, hills and valleys with a line through the center. In figured wood, the part of a particular curl that absorbs the most stain is the part on it opposite board that resists absorbsion.
Go over to "Mandolins in Progress" and look at the beautiful "A" made by Chris Baird. This is a perfect example of what I'm trying to describe. If your not aware of how it works, you might think he used 2 completely different boards, but then look at the dark lines at the center and see how they are the light lines on the other side.

[Jim Hilburn]

Here, I'll save you the trouble and post the pic here. Look at the forked curl that's slightly above the center and what happens to it on the other half.

[Jim Hilburn]

One more thing. The carving process can also change the relationship of what you see from one half to the other. As it slopes away from the crown of the back, there are some places where it appears to have a mirror image, but had you seen it before carving, it would have exibited the same out-of-phase relationship as in the center.

[Spruce]

A slipmatch is actually preferred (IMHO, of course) when "bookmatching" slabcut maple.

The figure tends to be more consistant in the finished back as the wood is cut from the same plane in the tree....

"This makes me wonder if it matters whether bookmatching is necessary. "

Let's include spruce in this discussion too...
There are a lot of non-bookmatched instruments kicking around out there, including some very well-known Loars.

One good way to detect whether spruce is bookmatched or not is to "gunsight" the instrument, looking right over the tailpiece towards the neck. #The grainlines tend to become more apparent when viewing them this way, and a non-bookmatch tends to stick out like a sore thumb.

You can also do this with a photo of an instrument, although tilting the computer screen can be a hassle at times... #http://www.mandolincafe.net/iB_html/non-cgi/emoticons/tounge.gif

[WoodyMcKenzie]

Thanks for the very informative and helpful posts! It makes better sense for me to slip match instead of looking for thicker boards to bookmatch. Actually,I prefer the looks of a one piece back that is assymetrical and interesting looking, vs. regular and tightly flamed two piece backs.It makes better sense to me from the point of view that there is one less joint to fail. Are there any disadvantages to one piece backs?

Woody

[Jim Hilburn]

There's far less 10" wide wood available than thick 5" wide wood, particularly quartersawn, if that's what you prefer.

[Chris Baird]

I've used slip matched wood on a couple mandolins, it looks great. You'd have to have a real anal customer to complain that the figure didn't line up just so. As Jim already said it can start out looking perfectly lined up and then when you carve it the figure is off a bit. The figure I really like, and which I have never seen in a mandolin, is the 45 degree big curls that run all the way across the back. I've seen some violins with it and they are very striking. You'd either need to use a one piece back or flip the wedges around such that the glue up was like a diamond instead of a triangle. It would make getting a flat side difficult.

[KenR]

Regarding the disadvantages of a one piece back, I've heard this opinion expressed. The glue joint in a two piece back is actually stronger than the wood, especially highly figured wood. Also, the range of expansion and contraction in a one piece is greater than in a two piece creating a greater risk of splitting. This may not be as important in mandolins as in the larger instruments. Again, this not my personal experience but a collector friend's opinion. You builders out there feel free to shoot it down. - Ken

[Chris Baird]

A glue joint can be strong but is still always a liability, esp. in slab sawn backs. Most one piece backs are slab sawn hence the stability concern with one piece backs. A one piece quatersawn back would have just as much stability as a two piece quatersawn back. I like slab sawn backs and think they sound good but I insist if at all possible that they are one piece as joint seperation is very common in slab sawn backs.

[Rob Grant]

I'm about to "stick-my-foot-in-my-mouth," but I don't see the back in the photo as a bookmatch example. I have to tread carefully here because I've never actually worked with much American maple. The back in the photo does not appear a true positive/negative as we get with our Oz equivalent. Here's a good example which was just sent to me by a local friend whose considering a beautifully figured back of Queensland Maple(not an Acer)for his next mandolin (thanks Mike Holland for the photo example).

Maybe the staining is twisting my perspective with the instrument example shown. Mike's photo shows what I would call a perfect bookmatched set.

[Chris Baird]

This back is cut on a skew which is about 30-45 degrees off quarter. #This photo better shows the bookmatch and in some places you can see the forks carrying through to the other side. #Some of the descrepencies at the center are caused by wood removal during the jointing process (not easy on a piece of wood like this). The skew cut creates a lot of abnormalities that make for two similiar but not exactly matching sides. You wouldn't see much of the forking if this were cut dead on quarter.

[Chris Baird]

This photo may be a waste because this mando is inbetween varnish coats but this is a dead on quatersawn back. The dark curls pretty much line up the light all up and down the back.

[Chris Baird]

And here is a bookmatch beyond argument. This is a skew cut as well.

[HoGo]

You will se the perfect mirror image with pos/neg reflections often only on the "flat" side of the bookmatched set. These two planes are separated only by the kerf width of saw used to resaw the wedges. The "outside" surfaces of the set were about 1 1/2" away from each other in the tree so the curls may be a bit off right from the start, especially in wood that wasn't perfectly quartersawn.

[Spruce]

"I'm about to "stick-my-foot-in-my-mouth," but I don't see the back in the photo as a bookmatch example."

Remember that comparing a final bookmatch in a carved instrument to one in a flat-back instrument can be a deceptive comparison....

Sometimes as much as 15mm or so of wood has been carved away in a carved back instrument, exposing an entirely different figuring in the wood....

In a flat back instrument, one might sand or plane away 1-2mm of wood at most--a big difference on the visual look of figure in a bookmatch....

[Dru Lee Parsec]

Remember that comparing a final bookmatch in a carved instrument to one in a flat-back instrument can be a deceptive comparison....
So true. #On a flat back instrument the amount of wood you lose due to the saw kerf and sanding the saw marks out can totally change the mirror effect. #I mean, we're only talking about 1/8th of an inch or so, but the grain can really change in that 1/8". #I'm only making my first mandolin but I've made quite a few dulcimers. Here's a back that worked out really well

http://www.brouelette.com/dulcimer/images/grandback.jpg
This was a good candidate for bookmatching because the grain was pretty consistent through the whole #board. So the left and right sides matched really well.

But look carefully at this one:
http://www.brouelette.com/dulcimer/images/walnutback1.jpg

The wood is beautiful, but the grain is so wild that there are pretty major differences between the left and right sides of the bookmatch. #And yet, there's only about 1/8" difference between the left and right faces.

I'm building one now where the left and right sides match pretty well, but if you turn the board over (so there's about 3/8" difference between the faces) one side is brown and the other side is light tan. #They look like they came from 2 different trees. #Wood's funny that way.

BTW, I know I'm moving away from mandolin talk, but here's what that piece looked like once it became an instrument.
http://www.brouelette.com/dulcimer/images/walnutback2.jpg

[Rob Grant]

Wow!

Some nice photos here. Too bad that's the bit that is held against the body and not on general display!

Anybody with an instrument shot of one of those beautiful, figured redwood tops (bookmatched or otherwise) that Spruce sells?

[Spruce]

Hmmm....
All the pics I have of the curly redwood are of one-piece tops--lousy for a bookmatching thread...

Here's a pic of Will Kimble's Half-and-Half mando...
Red Spruce on the treble side and Engelmann on the bass side...
Sounded great....

[MANNDOLINS]

HERE'S A SHOT OF A REDWOOD TOP
http://www.manndolins.com/F7FRNTC.jpg

[resonant68]

Nice looking redwood top BTW.
Bookmatching to me holds more than asthetics,it is about wood density per side.I believe you get as close as possible to matching each side in mirror locations when you book match.I know that carving away the wood changes the character of the wood in terms of density,etc.but to me it's more of a mental thing to know the wood is sawn and laid open as it were in the tree.
Maybe we obsess too much!

Now back to the redwood mando.Did you make your own bridge?It looks a bit more narrow on the top piece than any purchased bridges I've seen.Anyway,Looks very good.

[Spruce]

"Bookmatching to me holds more than asthetics,it is about wood density per side.I believe you get as close as possible to matching each side in mirror locations when you book match."

Why would you want to match wood densities when there is so much difference between the bass side of the top and the treble side, both in form and function??

Seems like you could make the case that the two halves might want to be very different, maybe even different species...

After all, your graduations are vastly different from side to side...

Humor me....
I'm just musing here... http://www.mandolincafe.net/iB_html/non-cgi/emoticons/smile.gif

[Rob Grant]

Actually there isn't really much diff in graduations from side to side (at least I don't). Minor bracing differences seem to be the best way to modify the treble/bass relation.

[Spruce]

Yeah, OK....

I just had a look at a couple Loar maps, and the difference isn't as extreme as I remember it...

There is some difference, though, with the bass side about .5m thicker than the treble side...
Not insignificant, but not as much as I remember it....

[oldwave maker]

More spruce 2 pc redwood- the mcdola

[resonant68]

I do agree with spruce in a sense but like I said,it's a mental thing with me.
I'm no expert by any stretch of the imagination and have learned lots from guys like spruce on this board.
But I was mostly talking about backs and not the soudboard,which I've seen often with different woods on either side.As well as different graduations.And different bracing,etc.

Truthfully I would like to see an instrument with near perfectly matching figure on the back.

Maybe I should try the slip joint thing too.

[delsbrother]

A slipmatch is actually preferred (IMHO, of course) when "bookmatching" slabcut maple.

The figure tends to be more consistant in the finished back as the wood is cut from the same plane in the tree....

"This makes me wonder if it matters whether bookmatching is necessary. "

Let's include spruce in this discussion too...
There are a lot of non-bookmatched instruments kicking around out there, including some very well-known Loars.
I was going to start up a new thread about bookmatching, but luckily found this informative one, so I'll add this question here..

I recently purchased one of the "blowout" Guitar Center Gibson F9s, and it appears to have a non-bookmatched top and back, but I'm not sure. I think the back is a slip match, since the flatsawn grain patterns don't match up (though the figure is pretty even).

The top, OTOH is pretty wild - the grain is very fine, and there's a lot of wavy ray fleck (I think that's what it's called) running cross grain.. So much so it makes wild swirling patterns where the surface changes direction - like the recurve, the scroll ridge, and the dome of the top near the bridge. In graphic arts we'd call this a moire pattern. Is there a similar phenomenon in wood? It's almost like there are two distinct grain patterns - a straight, very fine one, running from headblock to tailblock (I'm thinking this is the "grain") and another, which is curving, swirly, and very irregular, going in all directions (the ray?). In any case, if you look along the joint line of the top, the grain patterns are parallel but the ray pattern is completely different. So am I correct in assuming this is a sign the top is slip matched? Or is this a sign it isn't cut "on the quarter"?

I'm guessing slip matching is an inherently "cheaper" form of woodworking (and thus the reason it's used in the "lesser" grade 9 series). I'm personally taking Spruce's last comment to heart, because I really like the sound of this mando. http://www.mandolincafe.net/iB_html/non-cgi/emoticons/tounge.gif

BTW, my F9 was made this year, and has a much lighter, thinner finish than my (older) A9. I looked at a couple new A9s today, and the the light finish really makes these swirling patterns stand out. My A9 is a rich chocolate brown, and it covers up a lot of these features.. perhaps on purpose?

Darrell

[Spruce]

If the quality and value of the resulting instruments are any indicator, bookmatching is highly overrated....

The most highly prized violins ever made, and the most valuable mandolins ever made (including the most prized mandolin in existance), feature mismatched tops...