#2: If practical? Remove everything from the room, including the trim on the walls. Seal every crack you can find with caulk, putty and/or Great Stuff. Don?t forget to pay close attention to the areas around the electrical outlets and lighting switches, and where floors meet ceiling and walls. Paint the walls, ceiling and floor with a good marine paint/sealant; reinstall the trim. Move the door casing back ?? and attach rubber seals. Use a low-nap indoor/outdoor carpet for the floor; no foam padding ? that will only absorb moisture. Get a good ventilation fan that vents to the outside of the house, if possible. Make sure to install the fan on the outside of the house, to draw the air from the room as opposed to "pushing" it out. If you can swing it, build a ?vestibule? outside the entry door, to form a sort of ?airlock.? That way, at least one door is always closed. Install plenty of lighting, and all around - lots of low-watt bulbs to shine on your collection... keep several on at all times. The heat seepage will dry the air. Pay particular attention to any windows. Seal them up tight.* Worked for me. Four years later and no dust, no humidity, no mold. Like walking around inside a display case. It gets fairly humid here in VA at times; I was afraid I would also need a dehumidifier, but to date that has not been necessary. *my room has no windows, so this might present a problem for you. You might have to seal that sucker up.