Official Luthiers Forum!

Every year when Dave and I come back to work after the holidays we see a goodly percentage of what comes our way for repair as cracked guitars, mandos, etc. This is preventable as everyone here should know.

I tell new builders and repair people that job one before that killer bandsaw and wide thickness sander is doing whatever it takes where you are to create a proper and stable building/repair environment in respect to the relative humidity that you can faithfully and constantly maintain. I have never been a fan of suggesting that people build in a box or any of the countless ideas for trying to keep the RH in proper range.

What can result from a "dry guitar?"

1). CRACKs!!!!
2). Fret sprout
3). Loss of set-up as the neck goes into back bow.
4). Lifting bridges.

And more.... none of it good such as loose braces.

What's the proper range? For most of us it's going to be 42 - 48% or so give or take a bit. What's important is to stay in or near range AND avoid any rapid swings.

Here's my condo this morning and it's 7F outside this morning. I have a large, commercial quality humidifier on my furnace. I normally don't recommend these in that they tend to do very little in the moisture department and the wicks or whatever need maintenance and perhaps cleaning. But I liked the system that I bought and it's now in it's 6th year of flawless operation. I paid about $900 to have this system installed on my furnace. It's turnkey, set and forget and I spend my time playing instead of schlepping water. My system is plumbed to my hot water heater and furnace.

Just as important as getting the RH correct for building, repair or simply owning fine wooden musical instruments is having a calibrated hygrometer that you KNOW is very close to being spot on in the readings. Not going to waste my time on those who want to proclaim that their digital hygrometer is great, they all suck and if they do not suck now, the digitals they will suck in time as the electro mechanical mechanism breaks down with age.

The two hygrometers that I use are calibrated every year with wet-bulb technology. The smaller silver one is a more recent addition here that Mario recommended, we are Facebook friends, and these work great. I find that even the best hygrometers can drift a tad from year to year. I had to make a 3% correction on my gold one this year and the silver one remained spot on.

You can see from my front window that there is moisture in the air here. It's also very comfortable for we humans to have the RH at around 45%. No static electricity, warm feels warm, etc.

Regarding mold I've been doing this for nearly 20 years now and I don't have mold issues (nor does my condo LOL).

You go to a lot of expensive and trouble to craft your guitars (as I once did too) and repair folks have a duty to do no harm and have a suitable environment for us to take proper charge of the valuable personal property of others so there is no excuse for not doing what it takes to have a proper environment for wooden guitars.

Wanted to show you that it's possible even at 7F and if you follow Mario he will show you it's possible much colder than this too where he is.

Happy Monday everyone.

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Ann Arbor Guitars

I just had to go through this last week with a client who found a crack in the side of his $7000 custom made Taylor. The guy played on a zillion records and toured the country for 40 years. You'd think he heard of the rules at least once.

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"Act your age, not your shoe size" - Prince

Temp registers -17°C this morning here in Quebec City. That's 1.4°F to you, Hesh. You don't want to see what my shop windows look like. Tip : my calibrated RH meter (same as your gold one by the way, thanks for the recommendation) reads 48.


Pierre
Guitares Torvisse

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Pierre Castonguay

Bonjour pierre , c/est -17 c point une cadeaux. Il fait tres froid a castonguay.. Quand nous avons visite la ville de quebec c/estait dans l,ete, Est tres bon.

Hey Ernie, merci pour ce sympathique effort à écrire en français! Bonne année mon ami!


Pierre
Guitares Torvisse

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Pierre Castonguay

We have had a similar experience with a session musician. His 50's Martin withstood the swings because it had been seasoned for 50+ years but his new Martin is cracking and he does not understand why.

My electrics move too, the necks and my new Suhr the neck is moving like, well the neck is moving... I have a Strat too that the neck moved every time the RH changed and it did it for five years and then stopped.

Chris folks like us have to do lots of educating of our clients it seems. I hate being the one to tell them that their guitar is now in need of major repairs though, that's always a sad thing for me.

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Ann Arbor Guitars

Yay I'll bet that feels nice for you too with some moisture in the air. Happy New Year to you too Pierre I hope this C19 crap gets better soon so you can come visit us.

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Ann Arbor Guitars

We were grilling oysters and drinking beers on the back porch wearing just a light sweater into the night hanging outside with friends and now we got 6in of snow on the ground and it's 28deg. Pretty wild swing and probably not so good for a lot of guitars.

Best thing I did for my shop was to spray foam insulate the sub floor and the roof. I still have to shlep water from the house to the shop but it's not but once a couple of weeks and only if it's sub 20deg which we get only a few weeks a year.

I’ve seen folks speak about lacquering or applying shellac to the interior of the box after braced. I understand what they think they are doing but I’m not sure how I feel about. I wonder if it helps stability or not, I also wonder does it hurt the maturation of the instrument? What do you say? It seems like if it worked the big boys would have started doing it long ago. I do believe some of the old Selmer Macs were finished on the backs at least.

We have seen -32 C. for a few nights recently here in the Calgary area.....
All good in my shop though:

Hi Slim - Shellac or some kind of finish in the inside of the box has been discussed here dozens of times but regardless I'll let you know what I've said dozens of times and I'm sure some others will as well.

I think it's a poor practice that serves no purpose since moisture will permeate the shellac in hours or a day or two anyway. It may make repairs more difficult especially in the classical world where sound holes are smaller and arms are seemingly larger.... If repairs are needed any finish will need to be cleared from any area where glue is going to go. Top cracks usually require cleats.

So we can work around this and clear the finish and do exactly that but it's a PITA, not necessary and serves no function to shellac the inside beyond getting rid of shellac and for guys with a wood fetish popping figure where no one will even see it.

My view is that of someone who is up at 4:30 AM getting ready to go in and repair the 6 guitars that are waiting for me at my shop this morning. So serviceability and long term value for our clients is my North Star. To me a guitar is a tool for a musician not the latest creation of a woodworker with no insult intended. Most here see building as woodworking projects. We see it as creating tools for musicians and that means playability, tone and serviceability are much more important than a pretty rosette.

Guitars will need service like it or not. The best designs are servicable ensuring value for generations to come.

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Ann Arbor Guitars

Hesh yeah I could see how any kind of finish on the internals of the box could cause repairs issue. I guess in reality the finish has very little impact on moisture stability / protection from ambient air.

Exactly! Some finishes the plastic ones.... are moisture barriers to a better degree than shellac but in the world of sacred tone.... less finish is always desirable. If you have ever played a guitar in the white it's very different than after all the plastic crap is slathered on many of them.

In another thread someone is asking out loud why nitro is often, not always king in the finish world. Because it still lets the wood move, it's not thick or can be done with a thin film thickness, it's repairable and it's easy to use for many folks. Shellac is great too I jsut kept all mine on the outside.

Something that many here have not run into yet since they are not commercial but for better or worse what is "tradition" and "vintage" is always desirable to many. There is a reason why Martin maintains their value even though the designs have rarely changed, tradition in the guitar world is very, very strong.

This forum is littered with people who tried to build a better mouse trap often before they even fully understood the physics of how a guitar works and how what we have now works. Traditionalists reject change, new is not always better and life goes on. I've seen it a hundred times on this very forum.

Your question Slim is a very good question it's simply been asked dozens of times here before. The archives are great here once you learn to do the searches. Don't worry about asking things again we are happy to help.

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Ann Arbor Guitars

Can anyone recommend a good reasonable under $300 humidifier for our dry room . we are having an unusually dry winter here with humidities dropping below %30 causing me grief . in repairing glued up plates that are dried out. Thank you ! in advance FYI our dry room is 12 ft by 12 ft

I don’t have any stand-alone humidifier recommendations, because when I used them in the past, they wore out prematurely and provided disappointing performance. Maybe other folks have had positive experiences with some brands. I currently use installed units (both for humidifying and dehumidifying) manufactured by Aprilaire. Expensive up front, but worth it.

Go with a wick and not ultrasonic Ernie. The ultrasonic ones require very soft water or them make it snow all over the inside of your home...

When I was suing stand alone humidifiers the Kenmore ones with wicks worked great. You will go though a wick a month... or they start to stink and you will be carrying water every day but they work well.

It's no longer called Kenmore but still available under other brands. I have had 5 of these in my life and they work fine. We used 2 - 3 at our shop too before Dave invented our very own humidifier with preheated air, etc.

https://www.amazon.com/MA0800-Whole-House-Console-Style-Evaporative-Humidifier/dp/B002AQUK9S/ref=sr_1_16?crid=2J2VQEXFNEYDP&keywords=evaporative%2Bhumidifier&qid=1641475851&sprefix=evaporative%2Bhumidifier%2Caps%2C90&sr=8-16&th=1

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Ann Arbor Guitars

I use an AirCare 6 Gallon unit. https://www.acehardware.com/departments ... rs/4594099

Multiple fan and humidity settings. I add a 3 gallon jug of water each day and keep my shop around 35% RH. I'm getting close to hooking it up to a water line and installing a float valve to add water only when needed.

I know, "That's too low!" And I may be one of the crazy people who don't believe in building at high humidity. I live in Montana where RH really never gets very high. I take my instruments to even drier places, so I don't see any benefit in building for high humidity. I'd rather have my wood swell up a little bit than to shrink and crack. I do let my customers know this. In the summer my basement shop holds around 35-40% all by itself.

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Tony Thatcher
Bozeman, Montana

I also use the Aprilaire 800 Steam Humidifier in our central heating.
Even at -32 C (like last night....) it easily humidifies the whole house to 44% RH.

Interesting thread! Today’s outside ambient RH here in the subtropical summer is 91%. I warn customers who are thinking of importing instruments from cool temperate climates that they need to speak to the manufacturer or luthier first to ensure their shiny new guitar doesn’t need an immediate neck reset upon arrival. If the guitar was built at around 30% with a low saddle it may not be happy here.

I’d like to second Hesh’s point in the first post that avoiding rapid swings in RH is also important. Once an instrument has acclimated to a damp environment, a sudden trip into a controlled 45% can be dangerous. I have to do this at times where a repair involves cross grain gluing, like bridge reglues. I have a “purgatory” space in the ballpark of 55%-60% that instruments spend a couple of days in before they are stabilised at 45% for the repair.

I do all my own building at 45%. This works for my climate, I’ve never sent one of my guitars to live anywhere where winters are cold and super dry so not sure how they would fare. I’ve heard a few prominent U.S. luthiers remark that they think 45% could be a little too wet.

My wife reminded me of the holmes humidifier in the closet, so our dry room is at abt %40 humidity now. We get wide swings of temps here in winter, Josh is correct in thAT SUDDEN changes in humidity affect instruments. in LA whenever the santa ana dry winds blew n the fall, all the violin family instruments pegs would come unraveled in the tapered headstock hole.

Agreed! When I am gluing braces and assembling the body I keep the humidity at 35% for a month before and after.
The rest of the time I keep my shop between 40-45%

Love that black top Tiger Myrtle guitar, Hesh. I still remember when you where building out of your apartment - that was right around the time I started building as well.

Ahhh Florida - winter is the only time the dehumidifier doesn't run 24/7!

I actually run two ultrasonic humidifiers in my shop. Both do pretty well and hold about 2 gallons each. I fill them both twice a day. The humidistats on both are pretty much useless. They always read about 10% below what the RH is in the shop. I have a good Humidistat and a professional sensor that I use to check things and keep my Abbeon Hygrometer calibrated, which it really almost never needs. My shop is long and narrow, so I have one at each end. I can pretty easily keep it within 5% on either side of 40% which is my preferred setting. Anyway, one of the Humidifiers is a Homedics(sp?) one that you can refill from the top without turning it off. Sure is easy, compared to having to take the tank off and turn upside down and open up. Both do require regular cleaning of the little vibrating unit with a Q-Tip wet with 50/50 vinegar/water solution. I use filtered water in both along with those thingy's you can put in the water to keep the out the white snow Hesh was talking about.

This one. Not recommending Kohls, but it's what came up. Got mine at Costco. I've seen them a number of places. Not particularly expensive for a 2 gallon humidifier. Mine has been running fine for 2 years now.

https://www.kohls.com/product/prd-55428 ... lsrc=3p.ds

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Waddy

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