In 010116 MMDigest John A. Tuttle wrote about a humidifier:

> All it is is a plastic tube that's about 2" in diameter and about 3'
> long with about 20-30 5"-6" slits about the width of a table saw blade.
> The tube is stuffed with what looks like foam rubber.  To use it, you
> simply put it in a bathtub or large sink and saturate it with water.
> Then turn it upright and allow the excess to dip out.  Then you place
> it inside the piano near the tuning pins.  (I can see people cringing).

I think John is talking about the "Hydroceel(TM)" unit.  It works in
the winter and in the summer !

I used it and was happy with it.  The first time that I put it above
the hammers of my upright I was afraid some drops of water might fall
on them, but it never happens (fortunately!).  I was told one could use
it with normal water.  I think it is better to use demineralized
water.  The holes in my Hydroceel are now full of minerals.

I found some places on the WWW with more information:
    http://www.pianoexchange.com/faq.htm# Hydroceel
('# Hydroceel' is part of the URL)
    http://www.piano-house.at/tips/hydroceel.htm
(with a photo, price temporarily USD 81 instead of USD 66)

In the UK they are sold by  http://www.uk-piano.org/heckscher/
(no price-indication).  A Netherlands firm offers them for NLG 75
(about USD 31) including two attachment hooks and a bag to fill
the Hydroceel with water: http://www.andriessen-piano.nl/04C.htm

The Hydroceel units are quite common in the Netherlands.  If I remember
well it was a Netherlander who got a patent on it.

Wybe van der Wal
Rijswijk, Netherlands
http://www.casema.net/~wvdwal/