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I have someone from Florida making an enquiry. Average RH 49-90%, he says. Would you boost up your RH during bracing for a build like that?

I wouldn't. What the worst that can happen with too much humidity?? The arch increases?

There's some pretty easy non-radical things you could do: build it from mahogany with a cedar top and EIR FB, and use a laminated neck.

With humidity that high, more will happen than an increase in the arch. That much expansion (and arch) will often make things very tight and kill the sound. The action will also increase enough to cause problems. And if left at 90% for any length of time, the plates will experience compression set that may cause them to split at a higher RH than they otherwise would.

I'd consult the owner and make them aware of the potential problems and get them in on the decision. If you build it at higher RH, I would note that clearly in the warrantee and let the client know that moving to Arizona will not be a good idea.

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Just tell the guy to keep the guitar stored in its case with some humidipaks in the case. They absorb and emit moisture as needed to keep instruments at about 40% humidity. As long as an instrument is not left exposed to high or low humidity, it will be fine if stored in the case.

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Most people in Florida love their AC. Humidity control is difficult though. I would think it would be rare for the guitar to live at 90% all the time. The guitars that I have had that were made in a factory have been fine. I keep them in a case most of the time and pay attention to humidity.

The real issue this buyer would have would be if you made it just for Florida, then they decided to take it to Ohio or Colorado in the winter.

One other thing to consider is do you want to commit yourself to building in an environment with excessive humidity. I live in Florida and I'd avoid it at all cost just. Of course my wife doesn't agree with my "at all cost" philosophy.

It seems to be even more complex in the UK. We often have 90% in the summer and AC isn't common, but then when the central heating comes on in the winter, it can drop massively. I'm sure the "average" RH for different parts of USA must be considerably lower than the UK's. Should that translate to different build conditions?


I'm about to do some bracing: the humidity outdoors is 70%ish, not much heating needed at the moment as indoors is about 60odd%, so I'm going to prepare all the wood, then let it acclimatise in an indoor room with a dehumidifier for a couple of days [that long mainly for the braces] before gluing. I'll keep it at 50% while I carve the braces and glue the top and back to the sides. Maybe leave it at that for another couple of days to be safe, then get ready for binding.

I can't work indoors for anything apart from critical gluing and light brace carving.

I'm trying to make the best of what I can do. I very much hope that'll do. (???)

I don't sell the guitars I make, but if I did, I wouldn't do it. Do the big companies, IE: Martin, Gibson, Taylor, etc... change how they build? No, their product is their product, as is...even if a custom shop order. Your product is your product...and changing how you do things for this guy or girl will only lead to more problems. I play guitar, and have lots of professional playing friends - we / they recognize the guitars are tools of their craft, just like a chisel to us.

It has been bugging me for a long tim - I get tired of all the "purported mystery" and overthinking with guitar making; we're making guitars for goodness sake. A good friend of mine who is a very accomplished guitar maker was being interviewed about one of his more famous guitars and he was asked a long, deep meaning, introspective question that culminated in the interviewer asking, "what it all boils down to is, what does it take to make a guitar this special?" My friends answer: "wood." To me that says it all.

My rant for the day. Jamie

I'm gonna share this to FB for Dave Anderson, hope he'll chime in as he's a Florida builder.

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It's not unusual to have the humidity swing between 15% and 95% here over a day or two. Regarding cross grain gluing, the general rule of thumb in these parts is to allow 5 days for ready-to-assemble (and previously dried and seasoned) components to acclimatise to 40-45% RH. Others will differ in their views, but I've never had a problem using that rule. It may be overkill, but better that than a Pringled panel. There's usually plenty of other things to be getting on with if you schedule your work well.

Also, give your gluing surfaces a going over to get their surface energy up just before you hit them with the glue.

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

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Awesome, Trevor! Thanks so much, great to get some peace of mind on this issue! I'll leave it all for 5 days at 45%, before bracing and closing the box... The braces are all practically ready to glue, sides are assembled, kerfed and profiled, top and back joined, rosette installed, just need to final thickness and then I'll turn on the dehumidifier!

I wouldn't change the way you brace your guitars. Just tell the customer after he receives the guitar that it is his responsibility to keep the instrument at the proper humidity. I always build at 40 to 50 RH. I have customers that play out in the Florida humidity for a few hours but always return the guitar to the case and have no problems with the high RH playing outdoors. I have a humidifier and dehumidifier but rarely have to use them . The AC usually keeps the humidity close.

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Anderson Guitars
Clearwater,Fl. 33755

Thanks all. I normally brace at 40%, but I was thinking of putting it up to 50% in this case to hedge bets a bit....

I already suggested that, but it seems he wants good tone as well...

Absolutely correct. I assembled two soundboxes in Canada at 40%, moved to North Carolina for a couple years (left them in a humid attic), and then returned to Canada. Tops are permanently sunken at 40% now.