Presenting Part 2 of our series on how to care for works on paper in collaboration with paper conservator Karen Zukor, owner of Zukor Art Conservation in Oakland, CA. Part 1 highlighted environmental factors and in Part 2, Karen shares best practices for the storage of unframed works on paper.

STORAGE GUIDELINES:

The safest storage for all documents and works of art on paper is flat storage that provides protection against light, acidity, dust, temperature and humidity fluctuations, and air pollution. Proper storage includes archival containers, with no acids, dyes or adhesives that might bleed, or rough edges that might scratch. Objects housed within such an environment need to be separated from one another by interleaving tissues, to avoid surface abrasion, ink transfer and an accumulation of acidic deterioration.

Acid is the most harmful threat to paper; it can be absorbed into the paper from the air or any material adjacent to it; the result is discoloration and weakening of the object itself. Temperature and humidity have an immediate effect on paper: exposure to temperatures above 75′ F. can embrittle paper significantly, as does relative humidity below 30%. The process of aging is also accelerated by constant fluctuations in both temperature and moisture content: papers maintain their greatest strength when storage conditions are maintained at 50 to 60% relative humidity and 65′ F.

Moisture also encourages the growth of mold and fungus that will thrive if the print is exposed to high humidity even for a short period. The spores for such growth can be carried in dust and should not be allowed to accumulate in storage boxes or drawers.

Exposure to sunlight, whether direct or indirect, causes deterioration of both paper and the media employed. All-cotton papers will bleach in the presence of sunlight and wood pulp papers will darken, but both will weaken from exposure to both visible and ultraviolet light. Watercolor pigments are very susceptible to fading and many dyes and pigments are fugitive (likely to change, fade or disappear) in the presence of indirect light. Sunlight also acts as a catalyst in acid degradation; it will accelerate the physical deterioration of paper as well as its discoloration.

Given the inherent fragility of paper and its highly reactive nature with the environment, the following notes should be followed:

make sure all paper objects are in good condition before storage; carefully remove them from acidic mats and separate any labels or information to be saved if they are causing stains or indentations. Do not attempt to separate objects from mounts when they are adhered or try to remove adhesive tapes; these tasks should be performed by a conservator.

store all paper objects flat, not folded, in acid-free boxes, folders or envelopes. Objects should not be crammed tightly into a container nor allowed to move too freely; both could cause damage to corners and edges

interleave each object with an acid-free glassine tissue or medium weight acid-free paper to prevent one object from damaging an adjacent one. It is safest to have the interleaving papers cut larger than the object so that each piece can be lifted out on its own “support”; this will minimize direct handling and therefore damage

make sure any object with soft or friable media (pastel, charcoal, flaking pigment, collage) does not have additional heavy objects laid on top of it

keep storage containers away from light and dampness. Do not place boxes directly onto the floor or stack them tightly; there should always be some air circulating around them.

check periodically for insect infestation and the presence of mold or mildew

FRAMED ARTWORK

It is important to remember that sealed frames are still subject to environmental changes; moisture and heat can be absorbed through the dustcover, and dust can enter at the juncture of frame and glazing. Therefore, framed artwork must still be protected and stored properly. The following are suggestions for long-term storage:

Wrap each frame in paper to keep out dust and insects. Bubble wrap can additionally be used outside of the paper to protect fragile finishes and plexiglass which scratches easily. Plastic and/or plastic bags are not recommended because they trap moisture and can provide an environment conducive to mold growth. If storage is to be very long-term, avoid plastic or bubble wrap altogether and cushion with unbleached cotton material or polyester batting.

Avoid pressure-sensitive tapes (Scotch ™, masking, duct tape, etc) when wrapping frames or containers. Substitute cloth tape or undyed twine for tying.

Keep frames off the floor by resting them on padded supports (for example, bricks covered with carpeting) or on shelves lined with carpet scraps or acid-free corrugated board.

Store them away from exterior walls which tend to contain more moisture than interior walls and are subject to greater fluctuations in temperature.

If frames are stacked up next to one another, make sure hardware is not puncturing or scraping adjacent frame. It is standard practice to stack frames face-to-face and back-to-back.

Label the outside of each wrapped frame as to what the item is so you don’t have to open package repeatedly to discern contents; include information regarding artwork, glazing material, any special handling it should receive, and the date it was framed. If it is particularly heavy, note that on the label as well. Store with label facing out. Always write information in pencil, not ink.

If you are concerned about the amount of relative humidity in the storage area, tack up a humidity indicator strip and read once a week for a month to see how much fluctuation takes place. It is wise to check the strip at different times of the day.

Check periodically for insects and mold; keep storage area well vacuumed.