Official Luthiers Forum!

I am posting this thread because of a discussion taking place on another thread James WB posted about a guitar he received
from a client with cracks in the back. You can see that thread here -> http://www.luthiersforum.com/forum/viewforum.php?f=10101

At the extreme risk of sounding like a newbie arguing with the very experienced builders of this forum, and I don't mean to be sarcastic about this, I'd really like to take a further look into the merits of the given arguments. If you consider yourself to be experienced, professional, or like me, an amatuer, please participate.

Quite a few very experienced builders, people I make a point to read on this forum, have made it clear that using flatsawn wood for backs is not a good idea. James has a guitar that has cracks in it and the cracks are being attributed to the fact that his back (Mun Ebony) is flatsawn. Not by every poster in that thread but it gets my mind going.

Here's where my own personal conflict arises. I've seen a lot of nationally renown builder using flatsawn backs on acoustics.

PRS
R Taylor
Custom shops for nearly every large manufacturer
Applegate
Bozung
Crafters of Tennessee
Hiro Ebata (a Somogyi lineage maker)
McPherson

Compiling this list literally took me about 3 minutes by looking at pictures on Dreamguitars website. I look to all of these advanced builders and builders on this site for many things. Inspiration on design, sound, and of course wood selection. I'm miffed. I'd like to say I'm not arguing for or against but that's hard to say when I've thrown up examples that only prop up the flatsawn road.

I suppose it could be assumed that some of these builders would use a laminated back...but all of them? I didn't even go all the way down the list. Obviously there's more...and not just one more. What gives? Are we dealing with more Voodoo here? I've personally had flatsawn acoustic sets in my wood room for a couple years and in some cases they've moved LESS than some other perfectly quartersawn material I own.

My time on this forum has seen some very experienced builders leave because of the new guy telling the old guy he doesn't know what he's talking about. I've even worn that shoe....so I hope this thread doesn't generate that kind of reaction. Good debate and case building is what I hope to see here.

Chris

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There is no difference between the man that thinks he can....and the man that thinks he cannot.

I also have some flatsawn Madagascan on a guitar that I`ve had in my controlled "guitar room" for about 4 years .This guitar also had cracks that were fixed just after thickness sanding by flooding them with Ca. exactly the way the Mun Ebony was and it`s never had any problems.Of course it`s never left a controlled invironment for more than an evening or a day.It would be dang interesting to see what would happen if I hung it on the wall where the Mun Ebony has been hanging for 2 months.Of course when a person goes thru the whole building ordeal ,to do that would be insane in my opinion.I don`t have the cahones to do this.This is my personal favorite guitar of the ones I`ve built.But I have also learned to listen to the voice of experience.What`s right or wrong makes no difference to me in this situation..As for what Howard said,I think the real thing to learn is WHY TAKE THIS CHANCE?I KNOW I WON`t AGAIN.
James (Skin)

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James W Bolan
Nashville Tennessee

Some woods are more prone to cracking if flatsawn than others. The rosewoods, ebonies and ziricote are good examples. You take a risk building with woods like those if they are flatsawn. It's also a greater risk if the guitar makes rapid changes in humidity or is stored in a very low humidity climate. You can get away with some flatsawn areas in the back if they are past the waist in the lower bout. You can lower the risk by building with very seasoned wood in a lower than normal humidity shop, say 35%, and choosing the right species.

Other woods such as quilted maple are not as prone to cracking and you can't get that figure any other way. So some of it is knowing what woods are okay to use flatsawn. The figure of most flatsawn backs reminds me of plywood so I'm not sucked in by the beauty of the swirls.

Part of it is a public peception problem. A four piece quartered back is not what most are looking to buy, but those guitars solve most of the availability problems of fewer wide quartered boards. That problem is only going to get worse. If the buyer likes the looks of flatsawn then they and the builders are going to have to deal with the consequences.

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Ken Franklin
clumsy yet persistent
https://www.kenfranklinukulele.com

Many guitars are made with flatsawn wood. I've built many myself with no problems with cracking. Most woods have a prettier grain pattern when flatsawn. You will not see Quilted maple that is quartersawn and many guitars are being made with it. I do think flatsawn wood has to be seasoned properly to be stable enough for building and alot of exotic lumber is not that way when recieved and that can cause a big problem for the one useing it. So i do believe flatsawn wood can be used if the builder is experienced enough with the woods he is useing. I season all my wood myself so i now it is stable BEFORE i build with it. Any thing that is already cracked before hand is not suitable for a locked plate in my book. Humidity is also more important when careing for a flatsawn guitar because they do move more with humidity swings. This is what i have experienced and is my 2 cents in this matter.

I think it all boils down to shrinkage. Check this link: http://www.woodcentral.com/bparticles/woodmove.shtml and here: http://www.wood-database.com/lumber-ide ... -rosewood/ for EIR.

As you can see, the tangential shrinkage of EIR is more than double the radial and that's true for many of the woods on the list. To over generalize - if you build dry and store in a relatively stable humidity, flatsawn should be o.k.

I used a very thin piece of flatsawn curly maple on the back an instrument that unfortunately had to suffer through a week of near 100% humidity - it was bumpy and wavy for the week but it returned to normal once the humidity came down. Now there's only a little wave where it was super warped.

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http://www.birkonium.com CNC Products for Luthiers
http://banduramaker.blogspot.com

I agree with the choosing the right species.
Maple is one that is less prone to splitting, imo.
If I milled up something from a lumber yard,
I would let it sit around for at least 2 years, and see what it's gonna do.
I've noticed wood that is more flexible across the grain is less likely to crack.
Maybe not in the guitar world, but woods in general.
QS woods are more flexible than flat.

Howards point was risk? I took it as a defacto statement, although it makes sense that the risk is higher.

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There is no difference between the man that thinks he can....and the man that thinks he cannot.

I've built only one with a flatsawn Amazon rw back some 7 mo ago. I braced the back and closed the box at 40% and I pray for it once in a while, it is fine so far...
I still have a couple others flat (one Madrose, one Macassar). The Macassar will surely be made as a shop guitar so I don't care. My other 30 BS sets or so are all QS and I avoid buying flat like the plague. Other than that you can see them everywhere. Just browse any fine guitar dealer and maybe half will be flatsawn, perhaps excluding the ones made with Indian rw....

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Build log

Two pieces of the 3-piece back of my BRW 1969 Martin D-35 are flat sawn. In the late 1970's, a few small cracks appeared, which John Weisanen repaired using colored epoxy. They have remained closed and stable since then and the back looks good.

If you read through a list of descriptions of older guitars, such as the Martin list on the Elderly site, you'll be reminded that, after many years, most guitars will have some cracks. This includes instruments build of vertical-grain wood. Cracks are not good, of course, but a crack in a guitar is not the equivalent of a crack in an engine block.

IMO, since flatsawn wood is more likely to crack, it is less desirable for guitars, but that does not completely rule it out. For BRW I think the risk is reasonable; less so for zircote. This has to be a judgement call for the customer: he or she has to weigh the relative importance of cost, convenience, and appearance. Do you want a back with a nice figure for a lower price, or do you want to pay more or pick another wood so it can be quartered? For the customer to make an informed decision, the luthier or manufacturer needs to disclose the raised possibility of cracks and point out the need to carefully manage humidity and to immediately repair any cracks that appear.

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Tim Allen
"Never hurry, never rest."

Does anyone know how the manufacturers are dealing with these issues? For that matter, how are the high end custom builders that use flatsawn backs deal with the increased risk of the guitar coming back to the shop?

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There is no difference between the man that thinks he can....and the man that thinks he cannot.

I've already sent an apology to James for being so brusque. I used the late night excuse. {;->

Some flatsawn wood turns out to be very stable. It's a matter of why take a chance, as James said. In general it is more likely to warp and to split. You shouldn't be building guitars that require the owner to maintain a museum-like environment, IMO. Also, ebony is just not the most stable of woods. I didn't mean to accuse the supplier of selling bad wood, but there are a lot of suppliers now who don't bother looking for wood they can quartersaw, and don't really seem to know much about how best to process guitar wood. A lot of the public thinks that wild flatsawn grain is great stuff, so it's give them what they ask for. I think we should be educating the public instead.

OTOH, some people are baking back and side sets and claim an increase in stability. One source told me to bake between two flat metal plates at about 250º F. for 2-3 hours.

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Howard Klepper
http://www.klepperguitars.com

When all else fails, clean the shop.

Howard my fathers middle name was brusque.I just want to say publicly I appreciate your honesty.You tell it like it is. Your experience and advice are valuable and I really don`t feel an apology was neccesary, but I do accept and appreciate it.I`m sure everyone here agrees with me. I think I`ll go clean the shop.
Skin

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James W Bolan
Nashville Tennessee

I don't believe that a flatsawn back is more likely to crack than a quartersawn one. I do believe that some woods are more likely to crack and that certain boards within a species are more likely to, whether quartered or not. Shrinkage/expansion in a quartersawn board is greatest across the width of the instrument making it easier to predict what humidity changes will do to the instrument; that's the main reason for using quartered wood. Flatsawn can (and usually will) expand and contract in wacky ways -- not necessarily cracking but moving unpredictably. Hence the potato chip effect of humidity change on e.g. figured maple. Highly-figured wood, whether quartered or not, is generally more prone to problems than straight-grained pieces due to uneven expansion/contraction and to stresses within the wood.

Flatsawn is generally more difficult to bend; mostly it fails during bending rather than later. With many woods, I try to use the better-quartered pieces for sides. It's also a nice look: the quartered sides and flatsawn back almost look like one piece of thick wood hollowed out.

Don't most woods move more tangentially than radially with humidity changes? If so, I'm not sure I understand what you are saying.........do you mean it moves more along the width of the board than along the length?

I don't have a lot of guitar building experience but do have some woodworking experience. Seems that using flatsawn boards on the back instead of quartersawn brings tangential expansion into play rather than radial expansion. For woods that expand about the same tangentially vs radially, it may make little difference. For wood species where tangetial expansion exceeds radial expansion (most woods best I recall), then the back will move more with humidity swings so be more prone to crack.

I must say I agree 100% with Howard when he says it's not realistic to expect anyone to keep a guitar in perfect climate conditions at all times. Most don't have humidity control in their homes. And while there are some couch pickers that play alone and never take their instrument out, most decent players transport their instruments often.......playing with friends, used outdoors (in bluegrass parks or jam sessions, etc.), or to bars/restraunts, or stages/theaters, churches, etc. An instrument that is so fragile it can't be utilized in the real world is of little value in my opinion.

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Formerly known as Adaboy.......

Seems as if there are probably different opinions based on a number of factors... if you build professionally and have the issue of reputation and warranty to deal with, the risk will inevitably be more of a factor. Us amateurs can use the stuff more freely and see what happens

Also I guess location plays a part - over in the US you do have such a wide geography and a huge range in temp and humidity, not just across the country, but seasonally as well so the care needed if you have such an instrument is that much more important.

Over here in the UK the nornmal range is much smaller, RH wise between 45-55% so its relatively easy to build below 40% all year round and just expect a little belly in the summer... (although the harsh winter this year saw environmental RH fall down below 30%! Thankfully in our old houses RH tends to be kept a fair bit higher just by the daily use of showers and cooking!

Like all things there is a use for FS, and it can be darn pretty... just need to take more factors into account i guess.

One problem with the whole topic is that, given traditional construction methods, any wood can split. And most guitars will develop a split if they live long enough. What's the ratio of guitars with splits and without splits once they reach 50 years old? 100 years? At what point is it just wood being wood? At what point is it builder error? At what point is it owner abuse? Split happens.

It's all a big judgement call without a lot of hard data and with a lot of contradictory opinions and examples.

If movement is the only criteria, there are some inconsistencies to explain. A lot of people believe that flat quilted maple is OK to build with but according to standard wood movement charts, flat-sawn maple moves more than just about anything else you would likely find in a guitar. So it makes sense that brittleness (the opposite if split resistance) is a factor too and the fact that maple isn't particularly brittle is what allows people to get away with it.

Some rules of thumb for me:

-Always let wood acclimate to the shop. I don't think I've built with anything that I've had less than 6 months and I always store it on an upper shelf in the warmest, driest part of my shop. Most of my wood has been in my possession for years before I build with it.

-If the movement charts say that it moves the same or less than quartered spruce (which moves a lot) and it's not too brittle, I don't worry about it.

-If it splits of it's own accord before building, I wouldn't use it. The one exception would be Brazilian beam wood that has had a hundred years or more to stabilize.

-If it is very brittle (Brazilian, Ziricote, etc), I take extra precautions. Baking, alternative bracing, shellac, CA flooding, gluing in lower RH, etc. Usually some combination of those.

-If a customer asks for something I'm not 100% comfortable with, I will ask how they intend to treat the guitar, how they will react if a split develops, and then make an informed decision with them.

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http://www.chassonguitars.com

Darryl, you are correct. I think what Rick means is that because the ratio of thickness to width is so high in a guitar back that the expansion in the "thick" dimension will be almost nothing while it will be a lot in the "wide" dimension.

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http://www.birkonium.com CNC Products for Luthiers
http://banduramaker.blogspot.com

Ok Andy, that clears it up. Kent's explanation of the "brittleness" of the wood makes sense too.

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Formerly known as Adaboy.......

One more thing to add that's in Somogyi's book. He talks about the difference in surface area between wood sanded to say 80 grit and wood sanded to 220. Greater surface area means greater potential for moisture transfer. All those sanding scratches add up.

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http://www.chassonguitars.com

To me I think it matters more on the RH at time of glue up . I like to glue my plates under 40% rh. When it comes down to it , any wood can split at any time depending upon the circumstances . The are 2 kinds of wood , that which is cracked and that which will crack .
To be honest , as a builder I avoid anything that will be problematic . High figured woods to me are not a no no but the woods I found more stable as a figured wood are Maple , Mahogany , Bubinga and Sapele . I tried EIR that was highly figured and once braces, it cracke and warped to the point it was burned . I think it is a personal choice but know wood will expand across the grain not along it.
I learned early that gluing things at higher RH is more problematic that dryer. Much depends on where the guitar ends up . A guitar made in Hawaii and it ends up in Arizona may shoe more distress than one made in Maine and sent to Michagan.

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

I think one of the other issues that gives rise to more use of non quartered material for back and side sets is availability. While I haven't been building that long I have been in some form of woodworking all my life and I can tell you that it's harder today to obtain woods in certain dimensional formats that were very easy to buy 20 years ago. In the period of time that covers guitar building...say since since C.F. Martin 'made it so'.....20 years is not a lot of time.

I've got Hoadley's book....but Hoadley doesn't give strategies that deal with the scarcity of prime guitar woods (meaning well quartered) and it certainly doesn't explain how the large well known makers are dealing with their client base on this issue.

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There is no difference between the man that thinks he can....and the man that thinks he cannot.

Hmmm? I don't think it's at all obvious that the wood sanded with 80 grit has more surface area; likely it's the opposite. Which has more surface area: a square foot of gravel, or a square foot of sand?

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Howard Klepper
http://www.klepperguitars.com

When all else fails, clean the shop.

Gravel.

I'm not sure I believe that statement with regard to sanding scratches (Howard's point aside). I'd be very surprised if there was a measurable difference in time to equilibrium MC between a piece of wood sanded to 80 and one sanded to 220. If you have data though, I'll be happy to change my mind.

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http://www.birkonium.com CNC Products for Luthiers
http://banduramaker.blogspot.com

I guess it's possible that the rate of moisture transfer could change slightly when sanded to a different grit, but I don't think it would change the amount of moisture transfer.

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Formerly known as Adaboy.......