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Myths about plywood


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Ok, so Darren and I were talking about plywood the other night, and I brought it up in another post.

So I thought, well, lets take an educated look at plywood in guitar building.

First, what is plywood?

Well, by definition:

ply·wood ( P )

n.

A structural material made of layers of wood glued together, usually with the grains of adjoining layers at right angles to each other.

So, by definition, ANY guitar composed of multiple pieces of wood is a plywood guitar. If you put a maple cap on it's Plywood, if you join two pieces it's plywood.

Ok, now that's by definition and it's not want we consider plywood, I realize that.

So what are the benefits of plywood?

1. It is very strong, stronger than a comparable size of solid wood. A piece of 1/2" fir plywood is probably 10X stronger than a piece of 1/2" solid fir, by comparrison, a piece of 1/2" fir plywood is probably stronger than a piece of 1/2" solid maple.

2. It is VERY stable. Chances are a piece of plywood will not warp, or rather, it is far less likely to warp than a piece of solid wood of the same dimensions.

3. It is very dense, you have multiple thin layers of wood saturated with a glue and pressed and steamed together. It fills the grain between the pieces rendering a VERY dense wood.

4. Because it is usually cut as veneers and can be cut as a sheet around the circumference of a tree, LARGE sheets are possible (4x8 foot or better)

What are the downsides to plywood?

1. It's expensive, far more expensive than solid wood of the same dimensions. However, having said that, you are not likely to EVER find a piece of solid wood in the same dimension as a piece of plywood.

2. It's multiple layers, this means in humidity and temperature changes each layer expands and contracts differently. With the grain running at 90 degrees to the next piece, this causes issues with finishing edges. This is why most plywood furniture is finished with a veneer on the edge.

3. It's typically not available in thickness's large enough for a a guitar, 3/4" is the largest standard size you can typically find

4. There are many grades of plywood, from cheap utility grade (for sheeting houses) to aircraft grade for structural components in aircraft. this is also a plus, but for the sake of this arguement we'll consider this a downside as your average lumber yard will ONLY have utility grade.

So, why not use plywood in guitar making?

Well, no reason really, except that typical plywood is fir or poplar, neither of which is a really nice wood to work with. In acoustic guitar construction plywood is to dense and rigid, it won't allow nice vibration for the sound chamber.

In electric guitar building it poses major issues with edges and finishing. Anywhere you do a contour cut you'll see the multiple ply's, this can be VERY difficult to finish as the wood will be edge and end grain and soak up sealers etc differently.

Plywood also does not hold the fine thread screws as well that we are used to for pickup mounting, control cavity covers etc. The ply's of wood are very thin and as a result not that strong on an individual basis, it is the bond between the sheets of plywood that make it a strong stable wood.

Assuming you are using aircraft grade plywood, it will be very expensive to build a solid body guitar from in comparrison to say an alder blank.

Now, where do you see plywood in guitars? Well, by definition many places as noted above, but most times in instrument making, or ANYTIME the wood is glued together with the grain all running in the SAME direction as opposed to 90 degree's opposed we call it laminate. I have an old Framus Texan 12 string where the neck is made up of 52 laminations of wood. Yes, 52! It is the most stable neck I've ever seen, it survived a flood and the neck stayed perfect.

BC Rich in the 80's made many guitars out of plywood, mostly their low end, but a buddy of mine had a USA made BC Rich warlock that we decided to cut up one day, it too was plywood. There were 42 laminations in there. That was an incredibly bright guitar with sustain forever.

I think probably the biggest reason we as guitar makers don't use plywood is that it is not available in the thickness we would like for a solid body guitar. Also, there is of course an "aura" of guitar making that states using high quality woods. How many people are going to pay $5000 for a handmade custom guitar made of aircraft grade plywood as opposed to Hawaiian Koa with a 5A quilted maple top? Probably not many, on the same token, that identical 5A topped guitar for $5000 would probably only sell for $3500 if it were a 2A top, although the tone would be identical, remember, figured woods are graded for their figure, depth, symmetry, even-ness, and consistency through the board, not density or anything like that.

It would be very interesting to build 2 identical bodies, one out of aircraft grade plywood and one out of maple (at least compare a dense wood to a dense composite wood) and then using the exact same electronics, neck, etc, play them side by side, I'd almost bet money that the plywood one will be brighter with more sustain.

This isn't always what we want though, which is another reason plywood probably isn't used. We don't always want the brightest tone possible.

Anyway, I wouldn't let the fact that something is "plywood" change your mind about building or not building or refinishing a guitar, it's a fine material, used for many years in place of solid woods for good reasons :D

Anyway, most of the above is my opinion based on my experiences, your mileage may vary B)

Jeremy

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Cheers Jeremy,

I know someone that uses plywood for some resonator bodies and he says it's fantastic.

Plywood is good and has it's uses but personally I don't like working with it for the following reasons:

The top laminate splinters when it's cut with a jigsaw and with something like a guitar where the finish is so important, it's a pain in the backside. Although a bit of gaffer tape stops it.

Plywood splinters are the worst, all that glue makes them a nightmare.

Real care needs to be taken on the end grain.

But I do like working with it because:

You can build a shed from scratch in less than a day (providing that there's two of you and 24 cans of stella)

It's bendy, wicked stuff for making canoes

Stable

ANd finally........

........you can swipe it off building sites :D

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I know someone that uses plywood for some resonator bodies and he says it's fantastic.

In this case the stiffness and accoustic 'deadness' of plywood is positive, since the aim in resonator construction is to make a dead body, so that the resonator cone provides all of the guitars tone.

This wouldn't be so good in an electric or accoustic guitar where you want the wood to contribute to the final sound of the instrument.

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This wouldn't be so good in an electric or accoustic guitar where you want the wood to contribute to the final sound of the instrument.

I agree.

Plywood (in my experience anyway) is also quite thirsty, I thought that because of the high glue content I wouldn't need any pore filler as the glue is infused through the wood. How wrong I was. I was using filler primer and it drank more of that than Oliver Reed drinks whiskey.

Oh well, ya lives and learns :D

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It all depends on what kind of plywood you're using. There are many different grades of plywood and many different kinds of woods used in the laminations.

Building-grade plywood is usually made of softwood, and it often has voids in it. These two factors compound the finishing issues... the softwood soaks up a lot of finish, and you never know when you might come across a nice gap in one of the laminations.

If you move up into the higher-grade stuff like void-free marine-grade Baltic birch or mahogany plywood, you're getting plywood made of higher-density hardwoods that likely won't soak up a finish like a sponge, and they don't have the voids you get in the building-grade stuff.

Here are a couple of examples of plywood being used in "premium" instruments: Kubicki basses have necks made of 34 laminations of maple. Mesa/Boogie uses marine-grade birch plywood on their speaker cabinets.

I have entertained the idea of making a guitar out of marine-grade mahogany plywood, and i discovered that it's actually several times more expensive than building out of solid mahogany. I still might try it. The high modulus of the muiltiple laminates might balance out the lower-midrange "woof" that mahogany sometimes has, so it might work really nicely for a 7-string guitar.

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Darren, the mesa example is the same as the Reso' one - you want a speaker cab to be accoustically dead, that way your speaker gets to shine. This is not a property you want in a guitar, unless you want to show case pickups with virtually no interaction from the body. This could be an interesting approach to take, but it does run pretty contrary to the approach most builders take.

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I disagree jeremy.

Get a nice piece of "tone" wood, and do the bonk test. Get a piece of plywood and try the same thing.

You needn't disagree Perry, I agree, Tonewood will ring out far better than plywood every time.

But when we're talking Tonewoods we're talking a resonant wood like spruce or cedar or something of that nature. Typically a nice open grain resonant wood.

When you hit a piece of Aircraft grade plywood it will ring out very nicely too, I built a dulcimer a few years ago using Aircraft grade Birch plywood, the 1/8" Aircraft grade will ring out as much as a comparable sized piece of spruce (or it did in my experience)

But I would almost be willing to bet if you could laminate up a 1.5" thick blank in aircraft grade (which uses 9 lam's per 1/4") it would ring out as much or more than a piece of 1.5" maple.

However, having said that, you don't see a lot of solid maple bodied guitars either.

I understand when people say plywood we all think of the utility grade stuff that we use in housing or stuff like that, not the high standard aircraft grade.

As an interesting point, Aircraft grade needs to be made of a denser wood while still being allowed to resonate (or vibrate if you will) due to the high vibration levels in an aircraft, a standard utility grade plywood would simply come apart in very few hours in an aircraft :D

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I understand when people say plywood we all think of the utility grade stuff that we use in housing or stuff like that, not the high standard aircraft grade.

As an interesting point, Aircraft grade needs to be made of a denser wood while still being allowed to resonate (or vibrate if you will) due to the high vibration levels in an aircraft, a standard utility grade plywood would simply come apart in very few hours in an aircraft :D

I thin you might be right Jeremy. However, i have not seen aircraft grade plywood, only internal, external and marine grades (which in Australia, are all identical except for glue type).

what i definately have noticed, is when i get a nice "bonk" sounding piece of maple, and cut it into three pieces and laminate it back together for a neck blank, the "bonk" has gone.

Kinda off topic... As an interesting example of "bonking", grab a rosewood, ebony and maple fretboard and hold them 1/5 from the top (with just two fingers) and flick it 1/5-1/2 the way up from the bottom (hold it vertically). I always show this to clients to demonstrate the sound differences in timbers.

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I read that the critical difference that separates marine-grade and aircraft-grade plywoods from construction-grade materials (aside from the glue used) is that they are void-free.

Any voids or imperfections would lead to gradual weakening and potentially catastrophic failure as the woods are exposed to extreme loads and vibration.

The "bonk" test demonstrates that the particular plank's resonant frequency is within a certain range. As you suggested with the 3-piece laminated neck blank, wouldn't gluing that fretboard to another piece of wood result in a loss of the same "bonk"? If solid slabs of wood are all glued together, they're all contributing in a much more minor way to the overall resonance of the instrument. It's not like the body, top, neck and fretboard are all resonating at their own frequencies. The different wood densities are, if anything, just cancelling out particular overtones.

Original composite Steinbergers don't have that "bonk" because their resonant frequency is very high. Yet a lot of people praise these instruments for their tone. Very few overtones are absorbed by the instrument, allowing the true sound of the string be sensed by the pickups and electronics.

I think the only way you can guarantee preservation of the "bonk" factor is to build guitars out of a single piece of wood.

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I can't believe what I'm hearing. What are they feeding you two up there in Canada? :D

I don't want to make a long post, and I'd really have to think about it before I could make good sense against some of your statements, but I've said before that there's a point where laminations lose their benefit and begin to sound more like "laminations" than whatever type of wood they're made from. The bonk test isn't really to judge a resonant frequency since that changes with every carve you make. It's more to judge a decay time and high frequency absorbtion. And one or two laminations would provide one or two layers of cancellation. 50 plys = 50 levels of cancellation, or the remanufacture of 1 whole unit. But that finished unit is dead. If you like the sound of steinbergers, graphite brian moores, and other synthetics, have fun. But you can't polish a turd as they say. Void free, hand picked, marine grade, etc. still has a much higher glue to wood ratio than a three piece body. In all, I agree its a "sound" in and of itself. As is the steinberger (which I think sounds like poop-they were praised for their "tone" in a high fi/high gain world, not by any of my favorite guitarists) But if you want to hear more string and less wood, there're already a multitude of composites including the Parker that are doing just that. Trying to direct as much energy back to the string. So go string up your concrete sidewalk. B)

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Also depends on your playing style...if you're using EMG pups with a sustainer into a 200-watt 8x12 Marshall stack with the gain set on 11, all you need is a wood that stays in tune. If you're playing clean or acoustic, you want wood with good "bonk" and having 80,000 different grain directions going won't help.

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Also depends on your playing style...if you're using EMG pups with a sustainer into a 200-watt 8x12 Marshall stack with the gain set on 11, all you need is a wood that stays in tune. If you're playing clean or acoustic, you want wood with good "bonk" and having 80,000 different grain directions going won't help.

the wood sound translates through even in the emg example you give...after years of playing high gain i can tell you that i can definately hear the difference.

but the main thing is a solid hardwood guitar feels more "live" and has a subtle richness of tone that makes you enjoy playing it more,in my experience

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Guys, don't get me wrong, I'm not saying go build a guitar out of plywood, I was just stating some interesting facts about plywood.

There are different grades, some would or could sound good, some might not, it's got nothing to do with what they are feeding us up here in Canada, it's just comments on another type of wood, personally I can't for the life of me understand why anyone would build a body out of fir or poplar either, I don't understand people that think a PRS 10 top sounds better than a standard top, there are simply a bunch of misconceptions about wood out there, I was just pointing out some interesting issues with ply.

As for what parts in airplanes use plywood, well, wing ribs, sub spars, shear webs, fuselage formers etc, remember, I'm talking light planes here, not your average 747 :D

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You know who makes a good plywood guitar? Greg Curbow. It's phenolic impregnated and void free. (or at least all voids are stuffed with phenolic resin) So the guitars and basses are really dense but then he cuts them real small and thin so they have some acoustic bounce, still with great sustain. To me, that's the kind of plywood where you have made a solid material, rather than the sum of the parts. I still don't own one, :D but they are great guitars.

I feel the same about maple. It lets you design differently. Now you can make a real slim guitar because the maple can take it. But the slimness causes the maple to vibrate more. So you can go farther with that density. You can push the limits of guitar design. An all maple strat or les paul just kind of sucks, but if you design around the material, you can do something else with it. The Parker is the same way. It's a "dead" material combination, but it's slimmed out and contoured in such a way that there's some life put back into it. I guess I'm down on any plywood since you can accomplish the same type of thing with hard maple. If you make something real contoured like the Parker from ply you could have areas that, since they are carved out from top and back, are very weak because there's just a few glue joints between a few plys. Whereas a solid piece would be, well, solid. I don't know maybe its stronger than maple when carved thin too.

As for a finish, I'd say some satin or textured finish would be the best/easiest choice.

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about a year ago a friend and I scrapped an Epiphone Les Paul Jr. Used it for parts. Well when we scraped down thw finish we found plywood. I was shocked. To think a Paul made of plywood. So I would not hesitate to build with high grade Baltic Birch, use it all the time at work. A 5x5 sheet will run you about $60.00. At 19mm thick lam'd twice thats two bodies. Good stuff guys.

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I don't know if you can get it here, but back home they cunstruct cabinets and other stuff with plywood instead of MDF's and the alikes because of the weather,(PR) they use mnahogany, cedar and other woods to make plywood, and this are used in some instances to make speaker cabs instead of MDF because of the resonance of the wood...

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i've built two guitars out of plywood,both really just experimental.the only problem i ever had was with my warlock because you have to use two 3/4" an one 1/4" pieces with the 1/4" in the middle i glued they layers together and sanded down prperly but cause it was from two different sheets the 1/4" dried ot and shrunk a bit so there's now this small indent around the middle of ll the sides. i also have an explorer built of a mahogany plywood and it works very well.

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This was a thread with much varying information......

A few things - the tap tone or the "bonk" is the resonant frequency as well as the dampening of it! The less dampening you have the easier it becomes to hear the tone because it sustains more. A resonant frequency is decided by the stiffness and the weight of an element (e.g a guitar top) -that explains why the "bonk" changes with every carve you make (affects both the wight and the stiffness)!

-And a properly glued two or three piece body should have the same "bonk" as a one piece body of the same wood!

For instrument/tone wood use - the best is the "dry" plywood, not impregnated with glue or other polymers. The stiffnes added by the porefilling is next to nothing, compared with the the increased density - thus giving the same element (e.g the top) a lower resonant frequency and in most cases the polymer act as a damper.

I use birch plywood for the sides in this one: pit_03.jpg I have used three layers of 15mm = 45mm plywood. As the sides of an acousitic guitar acts like a reference for the vibrations in the top and back - it is nice to have the extra dampening and weight I find in plywood there. (the sides are actually thin - about 8-10 mm - so the guitar is stil fairly light)

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