Moistureproofing shop - now stage box

Sarah Fox sarah@graphic-fusion.com
Thu, 4 Nov 2004 11:37:53 -0500


Hi Bob,

Dehumidifier bars *alone* won't do it, as the RH will rise in the booth as
moisture comes out of the wood.  There has to be some way of transferring
the moisture from the inside to the outside.  This can be achieved with some
degree of ventillation in combination with the dehumidifier rods.  (In other
words, don't have the chamber too air tight.)  Fresh, cool air will enter
the chamber at some higher RH, and then it will be heated, driving down the
RH.  The air will then absorb moisture, and the RH will rise.  But
eventually, the warmer, moist air is vented to the outside (the way the
moisture is transferred), and it is replaced by cooler moist air, which can
be heated to lower the RH.  Put another way, cool air of a given RH has less
total moisture than warm air of the same RH.  Makes sense???  If you use the
heat approach, you'll find some very cheap and effective ceramic heaters at
the hardware store (perhaps $15 for 1000W of heat).  There's no need to blow
lots of money on dehumidifier rods, and the efficiency is exactly the same.

A noisier but more effective way to dehumidify is with a running
compressor-type dehumidifier, which will condense the moisture out of the
air and drain it to the outside.  I think you can get one of these things
for around $150.  I don't know which of these two methods would be more
energy efficient.

A third way to dehumidify would be with a dessicant in an *air-tight*
chamber.  (This might be useful for pinblock material, but it gets somewhat
impractical on a large scale.)  There's a product/company called Drierite,
out of Xenia, OH.  You can find it on the web. You can buy the stuff fairly
economically in 50 lb bags.  Drierite draws moisture out of the air and
incorporates it into its crystal composition.  Depending on the variety you
buy, the stuff can have an indicator that changes color when it has soaked
up as much moisture as it is able.  It looks a bit like blue kitty litter
and turns pink with moisture absorption.  If I remember correctly, it can
absorb about 5 or 10% of its weight in water.  When the stuff is
"exhausted," you can heat it in an oven to drive off the water, so that you
can re-use it.

Peace,
Sarah


This PTG archive page provided courtesy of Moy Piano Service, LLC