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I just had a 4 month old guitar returned to me for adjustment / service work. It's been living in a summer camp lodge where the relative humidity has been around 90% for the past month. No A/C to help with the humidity. It wouldn't surprise me if the crawl space below the floor of the lodge is so wet that the ground is muddy. All to say that the top and back plates have arched up way beyond where they were built.

The guitar was built between 40 and 45% and left home with reasonable action (6/64). The action is now sky high (6/32!) - which is totally unplayable. The guitar is now sitting in my shop which is hovering just over 40%.

My question - How long should I give the guitar to dry out and settle down before I attempt to address the issues? How long until I know that the moisture in the plates has reached about 45%?

Thanks in advance for your opinions / advice.

Phil

Ps. Another guitar built at the same time has stayed in my house the whole time (with A/C) and the action has gone up the predictable smidge in that time. So I'm pretty sure this is an extreme humidity issue.

When it stops moving if in that controlled environment?

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

You could pick up some desiccant dryer pouches to help bring the humidity down. Some of these may have helped the guitar survive the extra humidity.

Cal

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Remember, there are no stupid questions, only stupid answers!

Perhaps trying to dry it quicker could be counterproductive?
Even 90% RH to 40/45 is a big change already.
I would be tempted to leave it for a few days anyway first and see how it changes.
It's not just the top that moves, I was surprised to see a big movement in some new ebony fretboards mailed to me and left for just a day in my shop unstickered.

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

Since it was just due to RH conditions it could come back pretty quickly, 7-10 days if you're lucky. Detune the strings, perhaps as low as C or B just so the instrument isn't fighting anything too much. Bring it up to normal tuning every couple of days until the action is virtually back to where it started. All of the moisture studies I've been involved with and/or read have shown that MC takes an average of 12 weeks to return to normal... But it's a log function, so the first 7-14 days account for 90% of the moisture change and it slows down considerably after that. Fortunately, most of the woods used in guitar construction will give up humidity rather quickly. No need to mess with desiccant packs, ambient conditions in your shop will be more than adequate. Keep it out of its case and if you really want to speed things up just put a fan next to it on low.

One final note is that after returning the guitar to your customer, let them know that the action could change over the next 6 weeks or so and offer to correct the setup at that point if it is acting up. At that point it should just be a simple truss rod adjustment. Also, advise him about humidity and recommend storage in controlled climates whenever possible. If it can't be fully controlled, at least be prepared with a big bag of silica pellets.

Good luck!

Thanks guys. All of what you've offered is really helpful.
Patience isn't my strongest suit so it's good you've suggested to wait a week or more. I'll make sure to do that.
I'll also make sure to take up the advice about giving more detailed instructions for proper care.

Phil

I have had that happen a few times. One customer with a similar story to yours and another that over humidified his instrument with several in case devices running at the same time.

My experience was that even after a couple of weeks at 40-45% the instruments did not return to the pre injury level. Better but not 100%.

I had to tweak the neck sets on both.

Give it two weeks minimum to see what it does on it's own. I don't think that I'd use dessicants right away. I have filled guitar bodies with Uncle Ben's rice when old ones came in chronically damp and full of mold. Never tried it in your situation.

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It's not what you don't know that hurts you, it's what you do know that's wrong.

Too much moisture content can permanently puff up and distort wood fibers -- so my guess is that the instrument will not get back to as built specs on its own. To speed the equilibrium process you might consider suspending a little sack of calcium chloride in the body cavity.

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Ken Cierp

http://www.kennethmichaelguitars.com/

Continued thanks for the help guys.
I'll be patient.

Phil

I played my second guitar, still my player, at a Ren Fest for a number of weekends when it rained, about 6 or 7 years ago. It was pretty heavily exposed to rain and mist, and even though I know better, I stuck the gig bag in the corner at home when I got there and didn't take it out until the next weekend. After about three rainy weekends, it wouldn't play any more. It was so puffed up and the soundboard looked like a roller coaster, I couldn't believe it. I took the strings off and hung it in my shop for a month to 6 weeks at about 40% RH. Everything returned to normal. The top seam is more visible than originally, but it's still intact, and the guitar plays just fine.

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Waddy

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