Official Luthiers Forum!

Hi all,

Long time lurker here, first post.

I recently had a friend ask me to build him a guitar which he could take with him to Paupau New Guinea. I'm looking or any tips or tricks you may have to help a guitar survive in a tropical climate.

Thanks,
Sean

Build it in a higher humidity. If need be put the wood in a box with humidity added. Once you have the braces on the top and back done you have less to worry about.

Assuming the guitar is not going to live in an air conditioned space building it at 60 -70% humidity might be O.K., since New Guinea's R.H. averages 70 to 90 %. You might also want to use a water resistant glue. To me it seems like WRC soundboards are affected less by R.H. than spruce, but I have no data to back that up.

We have a number of clients who are sailors with boats moored at various Great lakes marinas. A couple of them have Rainsongs and other CF guitars just for use on the boats. CF guitars are often built a bit like boats, laid up exotic fabrics i.e. glass, kevlar, CF, and polyester or epoxy resin.

When considering building an instrument for a very humid climate I would consider what the boat builders do and have, they've had this problem for a long time and may have it licked.

BTW of the many CF guitars that I have played and we have one in the shop at the moment that I did a fret dress on they all have sounded so very good that it got me wondering.......

One day when all the good wood will be gone...

This thread is getting dangerously close to recommending an ov*tion

Well I do, and you're absolutely right
http://www.wood-database.com/lumber-identification/softwoods/western-red-cedar/
http://www.wood-database.com/lumber-identification/softwoods/redwood/
http://www.wood-database.com/lumber-identification/softwoods/norway-spruce/
http://www.wood-database.com/lumber-identification/softwoods/red-spruce/
http://www.wood-database.com/lumber-identification/softwoods/sitka-spruce/
http://www.wood-database.com/lumber-identification/softwoods/engelmann-spruce/

The quartersawn expansion rate for cedar and redwood is 2.4%, whereas spruces range 3.8 to 4.3%.

Cedar and redwood are more brittle than spruce, so they crack at about the same RH% drop from where they were braced, but they can take a lot more RH% rise without poofing up excessively.

Indian rosewood and Honduran mahogany have low expansion rates as well. But mahogany has international restrictions, so I'd go with the rosewood.

Aaah! Heretic.......

JK

B

_________________
My memory is so good, sometimes I remember things that never happened.

That is a worrisome proposition. Is the guitar is going to live primarily in a non-ac environment? If that is the case I suspect it will show damage over time no matter what you do.

But...

I would do a few things like

Cook the top as well as the back. That will make it less subject to moving with moisture changes, But it will still move.
Use a CF sandwich in all the braces.
Shape and glue the braces on a fairly high RF day.
Use an outdoor rated glue.
Use the most water resistant finish you can. Like a UV cured Poly or urethane.
Spray the inside of the box with an thin coat of oil based urethane. (it will kill a little of the sound but very little)

Or he could just buy a 'Travel Guitar' and you could make him a nice guitar for his return.

_________________
Joe Beaver
Maker of Sawdust

WRC may have good RH numbers but it has terrible "keep the stinkin bridge on and when you do shed the sucker don't tear up the top wood all to heck.... numbers...."

Repair folks have a special place in our dumpsters for WRC lifted bridges we encounter so very many of them....

Translation: When a guitar with a WRC top decides to divorce it's bridge it's more often than not a case of lots of torn-up top fibers and a rather nasty repair often with replacing top wood fibers from the bridge bottom etc. Although no data here WRC tops seem to shed bridges disproportionately to spruce tops but I can't prove it.

Back on topic look for information on Rick Turner's Antartica Guitar and that may be helpful. Rick built a guitar that went to Antartica and survived. Not the same as South America but some of the considerations might be helpful to ya.

PS: Because a guitar is made of composite materials with not a lick of wood on or in it it's still considered a Luthier who makes it......

Likewise if the wood can be taken out of Lutherie how is this primarily woodworking..... Off to work here to fix guitars!

Thank you for all the suggestions and advice, it's very helpful. Definitely given me alot to think about.

My friend is actually a piano player, but pianos are impossible to keep in tune in new guinea. Also due to the unreliable nature of the electric service over there, a keyboard isn't really an option. So he's learning to play guitar.

I actually suggested to him just buying a beater plywood guitar to take with him, we'll see what he says about that.

Carbon fiber guitars look really interesting, I'll be looking into that. A rainsong is probably out of his price range at this time. I do have a little experience working with fiberglass, so I imagine CF is similar. Hmmmmmm...

Whatever he ends up taking with him, it will most likely spend alot of time un-airconditioned. He might try to keep it air conditioned, but same problem as with the keyboard, the power goes out frequently and stays out for days sometimes. Pretty much the worst possible conditions for a guitar.

Thanks,
Sean

I think everyone is over-thinking it. Guitars existed everywhere before air-conditioning.
Build a regular guitar and tell your friend not to leave it out in the sun or rain.

_________________
https://www.facebook.com/profile.php?id=100008907949110

I would build it at the not far off of the commonly recommend 45% RH. Use a set up that will allow for the use of a shorter saddle for the humid condition and a slightly taller saddle for normal RH conditions. It seems like there must be some RH swings there as you say it's hard to keep a piano tuned. Building in a normal range will allow the guitar to survive the humidity swings, the top can withstand the compression forces that will occur as the RH increases, but probably won't withstand the tension forces it goes into when it shrinks as the RH drops.

_________________
Jim Watts
http://jameswattsguitars.com

"Carbon fiber guitars look really interesting, I'll be looking into that. A rainsong is probably out of his price range at this time. I do have a little experience working with fiberglass, so I imagine CF is similar. Hmmmmmm..."

I've built a back and side set using carbon fiber interleaved between layers of veneer. The tap tone was dull (tupperwaresque) but the guitar sounded fine (spruce top). If you use a porous wood (like rosewood) and plenty of resin the wood becomes saturated and somewhat impervious to moisture. I warm the veneer to drive out any moisture before doing the lay up.Carbon fiber is hard on HSS tools so carbide tipped is recommended.

Two-way truss rod.