If you use a humidifier, place it where it can humidify the entire room but not where it will blow moisture directly at the paintings. Most of the guidelines you would use in deciding how to display paintings also apply to works on paper. Since drawings and watercolors are even more sensitive to environmental conditions, however, you may want to consider the following precautions. Light is especially harmful to works on paper. Display them in a minimum amount of light.
Some experts recommend rotation of art on paper to dark storage every few months.
Reputable framers will know the steps to take to prevent future damage of your work on paper. Request buffered and acid-free paper, boards, and mats, which are the only materials that should touch the artwork. Ask the framer to cover the artwork with UF-3 Plexiglas instead of glass or plastic in order to filter out ultraviolet radiation. Cover the surface of any unframed piece with a sheet of acid-free paper or neutral glassine and store it flat in an archival folder. The most important step you can take to care for your paintings is to control the environment in which they hang.