Humidity

Discussion in 'Acoustic Heaven' started by Freeman Keller, Nov 12, 2019.

  1. Freeman Keller

    Freeman Keller Friend of Leo's

    Age:
    74
    Posts:
    2,066
    Joined:
    Aug 22, 2018
    Location:
    Washington
    I know I'm preachin' to the choir here, but if I save one guitar it is worth it. It has suddenly become winter in parts of the northern hemisphere and many of us have our home heating systems running full blast. Heating our air dries it out - it is not uncommon for the relative humidity indoors to be 20 or 30 percent while its raining or snowing or otherwise stinky outside. If you live on the other side of the world right now you can smile, but it will be coming your way in a few months. If you live in one of those tropical paradises where the humidity is always 50 percent and all you need to worry about is the occasional hurricane then please feel free to ignore the following.

    And if you know all about humidity and faithfully take care of it my hat is off too you.

    But for the rest of us - I have already seen two guitars this fall with serious dryness issues. Lets just review what that means. An acoustic guitar is built with a slight dome in the top, they are not flat on top. If you lay a straightedge across the top behind the bridge there should be a gap at each side - maybe 1/8 inch. As the guitar dries out the wood shrinks and that dome goes away (that is part of the reason its there in the first place). The more it dries the flatter it gets, it might even become concave. However if you can lay a straightedge across and its basically flat you have a dry guitar

    IMG_4373.JPG IMG_3623.JPG

    As the top goes down so does the action. The guitar will get buzzy and if you check the neck angle it will look like it is over set

    IMG_4375.JPG

    If you let it get dry enough the top will crack, usually down the center seam

    IMG_3622.JPG

    Some other signs of a dry guitar are sharp fret ends (the fretboard shrinks, the frets don't) and wonky finish - it will look wavy and uneven.

    That didn't happen over night and fixing it takes a while too. I start by putting a big car washing sponge in a baggie with a bunch of holes in it and sticking that inside the guitar. I put the guitar in its case and put another sponge/baggie in the headstock area and put it away for a month. It can be played during this time and I sometimes shim the saddle if I'm going to do that, knowing that when the top comes back up I can take the shim out. I'll usually dress the ends of the frets - they won't come back on their own.

    IMG_3624.JPG

    In a month I check the guitar, do any minor work on the frets and repair the cracks. Usually that means working HHG, AR or water thin CA into the crack and cleating it on the inside. If I feel the guitar is now stable I'll do a setup.

    Its a whole lot better to not let it happen in the first place and that is really pretty simple. Keep your guitar in its case with some sort of good humidifier. You can buy all sorts of things at a guitar store - my objection to most is that they cost quite a bit of money (but far less than fixing the cracks) and they often have small sponge that don't hole a lot of water. I use a simple cheap easy solution - I take a sandwich sized baggie and poke a bunch of holes in it - an ice pick, paper punch, crampons - just make a lot of holes. Dampen a kitchen sponge (without the pot scraper), wring it out and put it in the head stock area. If you are anal buy a hygromenter and put it in the case (google how to calibrate it) but I don't.

    IMG_5749.JPG

    Every one of my guitars has one of these, I check and dampen every week or so. My guitars stay in their cases even tho I have a small room humidifier in my music room. The never show any signs of dryness.

    End of lecture
     
  2. Freeman Keller

    Freeman Keller Friend of Leo's

    Age:
    74
    Posts:
    2,066
    Joined:
    Aug 22, 2018
    Location:
    Washington
    I should add a couple of things

    Your guitar is happy when you are happy. That means somewhere between 40 and 50 percent RH. If you spend much time below that your skin gets all ichy and scratchy, your prize dreadnaught hanging on the wall isn't happy either.

    Both high and low humidity are harmful, in different ways. Since low is much more common thats all I'll talk about. If you happen to live on a sailboat in the caribbean then you have a whole different set of problems (and my sympathy).

    Just because its raining outside doesn't mean the RH is OK. I live in the PNW and it rained a bit today. The RH in my house is 28%

    A room humidifier from Walmart can help a lot. I have one in my music room - it pumps about a gallon a day of water into the air.

    A good music store will be very aware of humidity control. My little mom and pop store (probably 3 or 4000 sq ft) has a closed loop humidifier built into their HVAC system. They tell me it dumps about 20 gal a day into the air. Their guitars are always perfectly humidified.

    You can buy an inexpensive humidity measuring device (called a hygrometer) at some guitar store, on line or at cigar stores (those guys watch their humidity carefully). Calibrate it and keep it where your guitars are stored. Don't worry about small daily swings. Worry a lot if it goes below 40 and stays.

    I never do a setup on a dry guitar. I might shim the saddle to keep it playing but I won't change anything until it is stable again. That might take some time.

    Most manufactures consider under humidity abuse. Its not covered by warranty.

    After all of this please don't bring me a dry guitar to fix. I have a habit of lecturing people who do.
     
    Torren61, black_doug, asatfan and 3 others like this.
  3. 57fenderstrat

    57fenderstrat Tele-Meister

    Age:
    28
    Posts:
    482
    Joined:
    Sep 4, 2019
    Location:
    Binghamton NY
    Those sponge bags are great ! Cheap and effective
     
    telestratosonic likes this.
  4. Obsessed

    Obsessed Telefied Ad Free Member

    Posts:
    22,047
    Joined:
    Nov 21, 2012
    Location:
    Montana
    Great advice and timely reminder. We use wood heat and keep a pot of water always going. Humidity rises like the heat, so our upstairs humidity is always about 10% higher than downstairs where the wood stove is. When it gets below 0°F, I add an old canner full of water to the top of the stove to keep the humidity at about 30% on the first floor. The acoustics stay upstairs all winter unless I'm specifically playing them downstairs.
     
    telestratosonic likes this.
  5. Milspec

    Milspec Friend of Leo's

    Posts:
    4,073
    Joined:
    Feb 15, 2016
    Location:
    Nebraska
    We have been in the single digits temperatures the past couple of days and my furnace is running around the clock drying the hell out of the place. I actually placed my music room in a spare bedroom and removed the ductwork. I keep the room closed up with a IR space heater and humidifier running to keep the room at 72 degrees and 45% RH all winter. I do have to refill the humidifier each day still so it is a pita, but never had an instrument suffer anything due to dryness.
     
    telestratosonic likes this.
  6. colnago

    colnago Tele-Meister

    Age:
    45
    Posts:
    278
    Joined:
    Aug 22, 2017
    Location:
    The Great White North
    We have a whole home humidifier on our furnace. Very little maintenance goes into this.
    It keeps all of the wood items in your home happy and keeps you healthier. Don’t over do the humidity though as mould can be a result and that it not easy to deal with.
    Happy happy.
     
    telestratosonic likes this.
  7. Boil

    Boil Tele-Holic

    Posts:
    675
    Joined:
    Oct 30, 2011
    Location:
    B.C.
    I ordered 5 little hygrometers from Amazon for about $13, I will callibrate and keep one in each acoustic case along with the guitar, can't hurt to keep an eye on things.
     
    telestratosonic likes this.
  8. Andy B

    Andy B Friend of Leo's Ad Free Member

    Posts:
    2,092
    Joined:
    Mar 16, 2003
    Location:
    Colorado
    One of the first things I did when we moved into our new house last spring was to install a whole house humidifier. The house humidity went from low to mid 20’s to mid 30’s, which is great here in Colorado. I keep Herco humidifiers in every case.
     
    colnago and telestratosonic like this.
  9. Tonetele

    Tonetele Poster Extraordinaire

    Posts:
    6,543
    Joined:
    Jun 2, 2009
    Location:
    South Australia
    A wise old Hungarian neighbour of mine , when I had a house, used to cook on a wood stove but always had some water going to keep up the relative humidity.
     
    colnago likes this.
  10. Tonetele

    Tonetele Poster Extraordinaire

    Posts:
    6,543
    Joined:
    Jun 2, 2009
    Location:
    South Australia
    Post script. Don't you folks in the US have room humidifiers? I've heard about these a lot over years here and it seems your dry, cold winters seem to be a problem. Please tell me what your experinces are.
     
  11. Charlie Bernstein

    Charlie Bernstein Poster Extraordinaire

    Posts:
    7,924
    Joined:
    Apr 26, 2003
    Location:
    Augusta, Maine
    Thanks! I'll start doing the straight-edge test.
     
  12. beninma

    beninma Friend of Leo's

    Age:
    42
    Posts:
    2,548
    Joined:
    Mar 17, 2017
    Location:
    Massachusetts
    We just went full arctic.. got up this morning and it was 17F, it was > 60F in the past week here.

    Even with the furnace mount humidifier it was 24% over where I keep my guitars. The humidity in the house has to drop to match the outside temps or you get condensation inside the house.

    Seems like good hard cases + humidity control in the cases is the only way I can make it work. One of the reasons I only have 2 guitars I suppose. I have my Tele and a Taylor. The Taylor hard case is way better at controlling humidity than the one I have my Tele in (Gator ABS plastic) but the Tele luckily is a lot less sensitive.
     
  13. Greggorios

    Greggorios Friend of Leo's

    Posts:
    2,102
    Joined:
    Jun 18, 2016
    Location:
    Patterson, NY
    I use a room humidifier and the sponge packs. Works fine.

    Vornado EV100

    [​IMG]
     
  14. archtop_fjk

    archtop_fjk Tele-Holic

    Posts:
    536
    Joined:
    Aug 4, 2009
    Location:
    Lebanon, NH
    Thanks Freeman - great advice! My favorite acoustic guitar has a low-humidity-induced soundboard crack, but I haven't considered fixing it as it plays fine and is part of its mojo now. But still, it would have been better to prevent it in the first place...
     
  15. stevemc

    stevemc Tele-Holic

    Age:
    63
    Posts:
    650
    Joined:
    Mar 7, 2018
    Location:
    cape cod
    i take mine into the shower each morning
     
  16. Flat6Driver

    Flat6Driver Friend of Leo's

    Age:
    46
    Posts:
    3,486
    Joined:
    Jan 14, 2013
    Location:
    DC Burbs
    OK I just bought a cheapy monitor for my office where I keep my acoustics. It's reading at 36% in the "comfort" zone. Guitar show told me that guitars are happy in the RH that we are happy. Frankly, *I* am a little dried out (I need to take this thing to work).

    What say you @Freeman Keller about this number? I'm on the East Coast. We sweat here in the summer.
     
  17. Freeman Keller

    Freeman Keller Friend of Leo's

    Age:
    74
    Posts:
    2,066
    Joined:
    Aug 22, 2018
    Location:
    Washington
    The usual range is quoted at 40 to 50 percent with 45 being about ideal. I try to maintain between 40 and 45 during the winter, but short excursions are permitted. I worry when its below 40 for several days.

    If you haven't done it your hygrometer should be calibrated. Google is your friend, you are looking for something that talks about a saturated salt/water method.
     
    Flat6Driver likes this.
IMPORTANT: Treat everyone here with respect, no matter how difficult!
No sex, drug, political, religion or hate discussion permitted here.


  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.