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Klarinet Archive - Posting 000189.txt from 1994/01

From: Cary Karp <nrm-karp@-----.SE>
Subj: Re: Humidity
Date: Thu, 27 Jan 1994 04:01:42 -0500

On Wed, 26 Jan 1994, Tom Ascher wrote:

> On the subject of cold weather (dry air) is it okay to put a "dampit" inside
> one of the joints of the clarinet while in its case? If so, do you need one
> "dampit" in each joint? Or, is it better to just lay a "dampit" inside
> the case alongside one of the joints? Incidently, I've been leaving my
> reeds (in a holder) in a small baggie. Seems to work out okay for an
> inexpensive solution!

The physical dimensions of a wooden object, such as a clarinet, change in
response to changes in the water content of the wood, which in turn
changes in response to variations in ambient relative humidity (RH).

Outdoor RH levels are usually quite high when it is cold, so cold weather
as such is not the villain. Indoor RH levels are lower because increasing
the temperature of a mass of air will lower its RH. This means that
HEATED indoor air is better able to absorb moisture -- which it will
happily suck from your clarinet, nasal membranes, and anything else which
is willing to cooperate.

Clarinets tend to crack in response to what are called humidity
gradients. These arise when the moisture content of the wood is
not evenly distributed throughout its mass. An example of this is
what happens when an instrument which has peacefully been lying in
its case is suddenly subjected to the brutal attack of a bunch of
dripping wet air being blown into it by its owner. If the moisture
content of the wood is comfortably high, this will pose little risk. If
the moisture content is too low, the mechanical stress generated by the
local swelling of the bore may cause cracking on the exterior surface.

There are a two basic ways to keep a clarinet out of harm's way. You can
provide a moistureproof barrier between it and the thirsty air, or you
can raise the RH of the air surrounding it by providing alternate sources of
moisture. If you have several instruments which are stored in the same
room, by far the safest approach to protecting the instruments would be
to raise that room's RH, either by lowering its temperature and/or by
providing it with a humidification device. Remember, though, that metal
keywork really likes dry air, and that the growth of mould is favored by
excessive humidity levels. (I'll be happy to discuss humidification
devices and appropriate levels of RH for objects consisting of mixed
materials if the subject appears to generate sufficient interest.)

You can also regard the clarinet case as an insulated "microclimate" but
a requisite for doing so is that it is really airtight -- which is rarely
the case <pun!>, nor even desirable during high-RH seasons. Local
moisture reservoirs such as Dampits obviously provide a source of
additional moisture inside the case, but in order for things like this to
work properly there must be a greater degree of air circulation inside
the case than is typical for one of conventional clarinet design.
Otherwise, the Dampit will provide moisture to the surface of the wood
closest to it, but this will result in a moisture gradient -- and we
don't want them.

A better idea, although one which I don't believe has been commercially
implemented, might be to have a special case for winter use. This would
ideally be airtight, lined with a good moisture buffer (one of a number of
materials which can serve as a moisture reservoir and maintain a desired
RH level in its immediate surroundings), and permit internal air
circulation. Since a clarinet is slobbered into while being played, it
would be self-buffering while in the case and would also replenish the
moisture in the buffering material.

So -- use Dampits if they make you happy, but be aware that they can also
cause trouble. Certainly use one in each joint. It might also be worth
NOT drying out the instrument as rigorously as possible after use (only
swab until visible moisture is gone) and putting the closed case in
something resembling a baggie while in transit. When back home keep the
case in the coolest room in your house.

   
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