HUMIDIFY YOUR GUITAR- NOW!
By Steve Carmody
It's winter here in the Mid-Atlantic states. Once the heat has been on for for a solid week,
I don't need to check the hygrometer to know that it's time to start running the humidifier.
As soon as you start warming your house during the winter months you are drying the household
air as well. Relative humidity of
less than 40%, over time, can cause many guitars and other wooden
things to crack, and if you do not humidfy the air in your home during this time of year
the relative humidity in your home is often well below 40%. Due to this seasonal drop in
humidity, and the fact that folks so often forget to account for it,
I inevitably see more
instruments coming in for repair of cracks in the top,
as well as general low action and string buzz problems. But
the most insidious thing about the drop in humidity is that its effects may not
be noticed for a month or two.
Most people who come to me because there are cracks in their
instruments arrive in January, February and March. And almost to
a person, they say: "It was fine last week and then I opened
the case and it was cracked." Well actually, in most cases, the
guitar had been drying out for two months or so, and didn't
reach the point where it was so dry that it couldn't contain itself
until "this week".
That is why it is critical to start humidifying your house,
room or the guitar itself- now.
Cracks caused by dry air are almost always along the grain lines in
the area between the bridge and the butt end of the instrument.
The soft light wood between the darker grain lines shrinks due to
the lack of moisture and separates from the denser and stiffer winter
growth. Cracking can also occur on the top next to the fretboard
extension above the soundhole.
Here is a picture of a classic center-seam crack, right down
the glue joint on the top below the bridge.
In some cases these cracks can be cleanly repaired, with relatively little
evidence of the repair, if the instrument is brought to a repairman
as soon as it becomes apparent that there is a crack. Most repairmen
charge by the inch for crack repair, so the shorter the crack the
cheaper the repair. Dirt and oil that works its way
into a crack over time makes it more difficult for the repairman to
hide the repair, so, early detection and repair gives the best potential for a more
elegant end result.
To avoid cracks which result from seasonal drops in humidity you
must always be conscious of the dryness of your home/store environment.
Many people who have forced-air heating have a humidifier built
into their system. If you are one of these fortunate, just set it
for a minimum of 45 % relative humidity( 50% is ideal for guitars, and people)
and you will probably never
have a problem with excessive dryness. For the rest of us, there are a couple of solutions.
I use a whole-room humidifer in the shop, but if you have
just one guitar, you could humidify it alone with an in-guitar
or in-case humidifier. Ideally, an instrument should be in its
case when it is not in use. This gives it a degree of protection
from the room environment. In-Guitar or in-case humidifiers, when
used as directed, provide adequate protection.
If you display your instruments, but do not have a humidifier built
into your heating system, there are a number of in-room misters and
vaporizers available. They work well when used as directed, the most
important factor being that the room temperature should kept
high enough to enable them to create the mist. In my experience,
if the temperature is too low ,they will not create a mist.
A low tech solution is to put a pan of water in front of a forced
air vent, or on top of a radiator, but this is much less reliable and
I would not recommend it.
No matter which method you use, any room with instruments in it
should be regularly monitored for humiditity level. The best thing
you can do ensure the health of your guitar is to invest in a
hygrometer with a digital readout. A hygrometer reads the amount
of moisture in the area where it is located. These can range in
price from $25.00 to $120.00. I have a $40.00 unit and it works
just fine. Ideally, you should maintain the relative humidity at
around 50 % where you store your instruments.Even if you use an
in-case humidifier, you should still get an in-case hygrometer to
be certain that you have adequate moisture to prevent cracking.
Overly dry air can have other effects on your guitar. One is that,
as a guitar loses loses moisture, strength in the top is lost, and
the top can tend to flatten. It is not unusual to get buzzing strings
at this time of year, particularly if your string action was already
set very low. As the top loses moisture it shrinks and settles down,
taking the relative height of the bridge to the neck with it, . The
net result is that the strings sit lower over the fretboard.
(Conversely, in the summer higher humidity can tend to swell
the top and the string height rises). While it is best to maintain
the humidity level, one solution for this can be to have a second,
slightly higher saddle made for use in the winter months. Indeed,
some guitar makers supply a second, seasonally appropriate string
Overly dry air can also shrink ebony fretboards,
causing fret ends to stick out. If this happens,
the solution is to file or "dress" the ends down. Dryness,
and, in turn, shrinking fretboards, can also tend to cause
forward bow in the neck. Again, while proper humidity is the best
solution, a remedy for this is to increase the tension on the
truss rod (a quarter turn at a time until the neck shows correct
relief as viewed at around the 6th fret).
Better yet, keep your guitar well protected from seasonal
environmental changes by maintaining proper humidity!
Steve Carmody is an independant guitar repairman and luthier with a shop in Silver Spring, Md.
He has been doing guitar repair and restoration full-time since 1990.
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