One more deodorizing compound: a bag of white volcanic rock sold by
Lee Valley Tools:

http://www.leevalley.com/garden/page.aspx?c=2&p=10175&cat=2,42194,40727

I haven't tried this in an instrument, but it took the musty smell out
of our cottage.  Not a Welte Cottage, sadly.

Jurgen Goering - Piano Forte Supply
info@pianofortesupply.com.geentroep
http://www.pianofortesupply.com/