One of the less expensive methods is to run positive pressure in the
darkroom as is done in "clean rooms". Blow air into the darkroom through
a quality HEPA air filter, preferably maintaining enough volume to
keep the room pressurized. This will tend to keep dust from drifting in.
Also, place a quality filter on the HVAC ducts (if any) into the darkroom.
A large percentage of the dust is blown in through there. You may have to
rebalance the air system to compensate for the increased resistance.
Lastly, vacuum often. A large portion of the "dust" in homes/elsewhere is
from dead cells shedding off of humans...
-- Steve Holzworth email@example.com "Do not attribute to poor spelling SAS Institute x6872 That which is actually poor typing..." SAS/Macintosh Development Team - me Cary, N.C.