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Advice for constructing a guitar for a high humidity environment

J.Banning

Member
Messages
38
Does any one have any pointers for building an acoustic guitar that is going to be in an extremely high humid environment?

I'm building an acoustic guitar for a missionary that is going to Papua New Guinea. Just wondering if a standard nitro finish would work? Or should I use something else? I was thinking about maybe spraying the inside with finish too besides just using a sealer to help seal the wood. Any pointers would be greatly appreciated... Thanks!
 

EADGBE

Senior Member
Messages
12,338
Yes I'd spray the inside. Or at least apply finish to the inside. Since no one would see it you could brush it on. Is polyurethane ever used on acoustics? If so that's what I'd go with. Because I think it protects better than nitrocellulose. Oil based polyurethane may be better than water based. But I'm not sure as I've never finished a guitar.
 

bibir

Member
Messages
919
Hi, I live in Indonesia.. If you're thinking about humidity level for the guitar body, any type of finish will be ok here.. I have 3 Martins 000 guitar, I think it is sprayed in nitro, and it is fine as long as I store it in gigbags or hardcase when I'm not playing it.. Put some humidifiers in the case. The only thing that you should remember is to let the neck adjust first by not rushing opening and playing it the moment you arrive.. A day or twowould be enough I guess..

Post some pics when you're done making it..
 

cherrick

Member
Messages
2,584
Low Humidity is the problem. Not High Humidity.

You don't do anything for high humidity.

For low humidity, if you do nothing you're going to ruin the guitar.
 

Danny W.

Member
Messages
931
Low Humidity is the problem. Not High Humidity.

You don't do anything for high humidity.

For low humidity, if you do nothing you're going to ruin the guitar.
Although this is common wisdom, my own experience tells me otherwise. We lived in a tropical climate for awhile; after a short time the metal parts on my guitars started to oxidize and I had to change strings weekly. Our house was not air-conditioned and when I took a guitar into an air-conditioned club it was all I could do to keep it in tune for the rest of the night. Worse, the necks felt wet when I played them--I had to keep wiping them down and using powder on my hands.

I quickly closed off the guitar room from the rest of the house and installed a room dehumidifier, which helped a great deal.

I've been living in a desert climate for the last 11 years; my guitars are much more pleasant to play and strings last a long time. Only one has exploded so far ;)

Danny W.
 

DRS

Member
Messages
12,354
Low humidity causes wood to shrink resulting in fret sprout and even cracked tops on solid acoustics. High humidity results in poor tone and in extreme examples, wood swelling to the point that bindings can pop off and tops warp.
 

Axis29

Member
Messages
3,595
The biggest factor is CHANGE in humidity, as Danny W. states. Swings in temperature are also a huge factor. The quicker the changes, the more the danger. This is why Bibir suggest leaving the guitar in it's case for a while.

The shrinking and swelling is what causes the finishes to crack because the wood changes at a different rate than the finish. Top cracks can happen due to the natural grain of the wood and it's tendency to check at the edges. This is a factor of differing changes in humidity, the edges dry faster... But, a lot of the time I think it also comes from the differences in stress between the field of the wood and what it is glued to, or how it is glued. Adding finish to the inside slows the changes in the wood itself and should help protect it a bit. But remember, you'll have to finish it after it's assembled to really seal it properly and also still have the adhesives applied properly.
 

Whiskeyrebel

Silver Supporting Member
Messages
30,729
Has anyone made acoustic guitars from thermally treated wood, i.e. "torrefied" or "baked" wood? The process was invented to make exterior wood more weather-resistant so it seems like it would be a good choice for giving the same properties to an acoustic.

Because it changes the properties of the wood, it's likely that you'd have to use a different wood to get the same properties as, for example, air-dried or kiln-dried spruce. IIRC the wood gets lighter and stiffer but also more brittle.
 






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