Following a brief review of how moisture enters and leaves cellulosic fibers and paper, and methods used by the conservator to wet up and dry works on porous supports, there is a description of a moisture chamber into which arm ports are cut so that the conservator can conduct treatments under controlled moisture conditions. The moisture chamber is set on a suction table; moisture is introduced by means of an ultra-sonic humidifier and removed through the suction table. A technique for stain removal and lining within the chamber is then outlined.