Kimberly Nichols and Debora Wood
Understanding the characteristics of both paper and media is critical for the preservation of prints and drawings. Exposure to potentially harmful factors such as light, humidity, elevated temperatures, and pollutants can accelerate the degradation of works on paper. These factors can affect materials in different ways—fading or discoloring some media more than others, and lightening or darkening paper—and shift the visual balance of the work. Likewise, there may be inherent faults in the original materials that comprise the artwork. For instance, wood pulp fibers in paper (a common constituent of newsprint) or residual chemicals from the papermaking process can cause paper to degrade more rapidly. The oil binder in some printing inks may absorb into the paper it’s printed on and discolor it over time.
Works of art on paper are especially vulnerable to damage from poor handling or inadequate storage methods that can cause creases, tears, or deterioration. Paper can be compromised through contact with chemically unstable materials used for display or housing. Materials containing wood pulp, which can be found in some mat boards, are particularly susceptible to degradation and increased acidity that damage works adjacent to them. Establishing and implementing best practices for handling, display, and storage are the first steps in protecting artworks. Fortunately, modern technologies and research make it possible to control interior environments to make them suitable for works on paper. Conservators, curators, and other specialists have devised the best methods for handling, displaying, and storing art.
Outlined below are the most common factors that affect the preservation of prints and drawings, followed by a list of websites and publications for more information. While these guidelines generally apply to the preservation of photographs as well, there are some slight differences in their storage and display requirements specific to the medium, which should be considered. For an introductory overview on caring for photographs, consult Northeast Document Conservation Center’s Care of Photographs; for more detailed information, see American Institute for Conservation AIC Wiki: Photographic Materials. If you have an artwork that is damaged, it is best to contact a trained conservator specializing in works on paper. Even quick or seemingly minor repairs, if undertaken without appropriate expertise, could cause greater harm (see “How to Choose a Conservator” and “Find a Conservator” on the AIC’s website).
All works on paper are susceptible to cumulative and irreversible damage from exposure to light. Ultraviolet (UV) radiation (wavelengths below 400nm) is the most harmful part of the electromagnetic spectrum. Light can cause fading of media, particularly organic and dye-based colorants. Watercolors, color prints, and some writing and drawing inks are especially vulnerable to light damage. Likewise, toned or colored papers can fade with accumulated light exposure. Light can also discolor and degrade papers depending on their content. Papers containing wood pulp, for example newsprint, are particularly susceptible to light degradation. Methods for limiting light exposure to preserve works of art include:
- Eliminate natural light whenever possible, for example, by blocking or filtering light from windows and skylights. Polyester films can be applied to windows to filter out ultraviolet (UV) radiation.
- Equip artificial light sources that emit high levels of UV, such as fluorescent bulbs, with UV filters.
- Frame works on paper with UV-filtering glazing (acrylic or laminated glass), such as OP-3 or UF-5 acrylic, Optium Acrylic, or Ultra-Vue Laminated Glass or LUXAR Classic; install UV-filtering films in display case covers or ensure that they constructed of UV-filtering material.
- Light levels for works on paper should never exceed 10 foot-candles, or approximately 100 lux. For sensitive media, such as watercolors and Japanese woodblock prints, light levels should not exceed 5 foot-candles, or approximately 50 lux (one foot-candle is a unit of illumination equal to that emitted by a source of one candela at one foot distance; or one lumen per square foot is 10.764 lux). A light meter can be used to measure the amount of light cast on the surface of a work of art.
- Restrict light in the display area or cover with an opaque barrier when works are not being viewed. Lights may be equipped with motion detectors to turn lights off when the display area is unoccupied.
- Periodically change the display of prints and drawings so they are not always on view. For more on determining an appropriate time span and rotation schedule for presenting works on paper, see “Duration of Exposure” in Guidelines for Lending Works of Art on Paper on Print Council of America’s publications page.
Temperature & Humidity
Fluctuations in temperature and humidity cause paper to expand and contract, as a matter of course. If changes in environmental conditions are extreme, this movement can structurally weaken or distort (buckle) paper. Media can also be disrupted; pastels, thick applications of gouache, or screenprints, for example, may crack or flake. Papers that are thin, short-fibered, and calendared (such as tracing paper) are particularly susceptible to changes in humidity. Warm, moist conditions accelerate deterioration, and encourage mold growth and insect activity. Mold spores and iron, which are often inherent in the paper, can promote the development of foxing spots, or small reddish-brown stains. Conversely, extremely dry environments can cause papers to contract so much that breakage or severe distortion can occur.
The ideal environment for works on paper is one that is consistently cool and moderately dry. The following measures are strongly recommended:
- Temperatures where artworks are stored and displayed should be controlled within the range of 65°–72°F with a fluctuation of no more than +/-5° within a 24-hour period.
- Relative humidity (RH) should be controlled within the range of 40–55% with a fluctuation of no more than +/-5% within a 24-hour period. The narrowness of range is less important than avoiding rapid fluctuations.
- Avoid displaying or storing works in areas where extreme shifts in humidity and temperature are likely to occur, such as attics, basements, and entranceways; objects should not be hung near heating or cooling sources, or air-conditioning vents. It is also recommended not to hang art on uninsulated exterior walls as they could conduct temperatures from outside.
- Matted works can be sealed when framing to retard environmental fluctuations (see Handling & Housing section below).
Mold thrives on paper that is in a warm, moist setting, which leads to the paper’s decomposition, sizing loss, and discoloration. Insects (such as silverfish, bookworms, booklice, termites, and cockroaches) and rodents often seek out conditions favored by mold, especially dark, damp environments. These biological agents can cause extreme physical damage to works on paper and book bindings.
Preventive efforts are favored over the use of pesticides or fumigants. The following best practices are encouraged to guard against mold, insects, and rodents:
- Maintain a relatively cool, moderately dry environment as outlined above. Most molds require a humidity level of above 65% to begin to grow. Therefore, do not store artworks in areas that are prone to dampness, such as basements, and if a space becomes damp use a dehumidifier.
- Ensure that storage and display spaces have air circulation; do not store works directly on the floor or in enclosed rooms or cabinets where air circulation is restricted.
- Routinely clean floors and surfaces with dry-mops and microfiber cloths to remove mold spores, dust, and detritus.
- Inspect areas for evidence of insect infestation. Sticky traps can aid in monitoring some insect activity. If an outbreak is detected, immediately contact a certified pest professional to assess the environment.
- Make sure that artworks are not framed directly against the glazing. Restricting air space between the artwork and the glazing can encourage condensation and mold growth inside the frame. Media can also transfer to the glazing if in direct contact with it.
Pollutants, such as exhaust, tobacco smoke, and other particulate matter that contaminate the air, are harmful to paper. In addition, making the surface of a work dirty by depositing particulates, pollutants can affect the work’s chemical and structural stability. For example, sulfur dioxide, a gas produced by the combustion of fossil fuels, causes degradation and discoloration of paper. It also chemically and visually alters some pigments; white lead, used for heightening in wash drawings, darkens upon exposure to sulfur dioxide. Pollutants can also derive from construction and finishing materials such as wood, plaster, paint, and fabrics. Since these materials are used to make frames, display cases, and storage boxes and furniture, they should be tested to ensure they are not harboring harmful gasses. Oddy testing is one such procedure that can determine whether or not a material is safe for works of art before it is placed in a sealed environment. Some measures to protect prints and drawings from pollutants include:
- Equip heating, ventilation, and air conditioning (HVAC) systems with filtration at intakes that remove airborne pollutants and particulates.
- Mat and frame works to reduce exposure to airborne pollutants. Particularly vulnerable works could be sealed in frame packages (see Handling and Housing section below).
- Ensure that storage containers (boxes or drawers) and case display materials have been Oddy tested to identify the presence of pollutants or corrosive gases that are harmful to artworks. Materials should be retested before use as proprietary formulas and manufacturing processes can change without notice.
- Prints and drawings should not be placed in direct contact with materials that could be damaging. For example, works displayed in cases should be set on top of an acid-free mat board or an impermeable film base (e.g., Mylar) for protection.
HANDLING & HOUSING
Paper is such a ubiquitous and commonplace commodity that is usually treated in an indifferent manner: notepads, newspapers, magazines, and other items are disposable; many do not fret over fingerprints. However, when paper is part of a work of art, one needs to be more aware of paper’s vulnerability and ways to prevent physical damage.
Without careful handling, a print or drawing is easily creased and torn, and dirt and oils can be transferred to it from handling or contact with other surfaces. Whenever possible, it is best to limit direct handling of art on paper. When one must handle an unmatted or matted work, follow these guidelines:
- Make sure pathways are free of obstacles and prepare a clean surface that is clear of objects, food, and liquid before moving an artwork.
- Ensure that your hands are washed and clean. Handling artworks directly with clean hands provides the most sensitivity. In some cases, it may be preferable to wear nitrile or thin cotton gloves, especially when visitors are not accustomed to handling artifacts with their hands or when there is not much oversight with handling. Keep in mind that nail polish can transfer when rubbed against surfaces.
- Be sure that unmatted prints or drawings are supported in a folder, or flat upon a clean sheet of mat board, heavy paper, or a blotter before moving.
- Always use two hands to gently move work, keeping it horizontal. If an unmatted work must be handled, be responsive to the grain (the direction of fibers) of the paper and allow for a natural curve of the sheet to prevent creases; do not grip, twist, or forcibly bend.
- Be careful not to touch or drag anything across the image surface including interleaving paper or loose clothing (long sleeves, untucked shirts, ties, scarves, dangling jewelry, ID tags, or other accessories). Pastels, screenprints, and mezzotints are particularly vulnerable to surface damage.
- To avoid accidental spittle landing on the surface, it is best to not talk while leaning over or facing an artwork.
- A sheet of smooth, acid-free, interleaving paper (non-buffered or lightly buffered) or neutral pH glassine should be used to protect the surface of artworks. Loose works should never be stacked directly on top of each other without interleaving paper between each sheet.
- Use only a soft pencil when taking notes or drawing near artworks.
When determining the appropriate housing for prints and drawings, it is important to consider the number of works in the collection, their sizes, and type of media. Individual works can be matted, framed, encapsulated in Mylar envelopes, stored in folders, or in some instances, rolled. Works in mats or folders can be stored in acid-free boxes or drawers. Framed artworks, when not on display, can be stored in vertical bins, hung on wire screens, or laid flat (face up) in drawers.
Storing large, unframed works can be particularly challenging, especially if they exceed the standard maximum mat board dimension: 5 x 8 feet. Although not ideal, particularly oversized works can be rolled around the outside of a large-diameter, acid-free, cardboard tubes. Determining the appropriate diameter of the tube is dependent upon the type of media and paper support of the artwork and its dimensions, but the tube diameter should not be smaller than 6 inches. For more information, see Michelle Facini’s essay “Storage solutions for large format works on paper” in Art on Paper: Mounting and Housing (British Museum, 2018) and Storage Solutions for Oversized Paper Artifacts by the Northeast Document Conservation Center.
As discussed earlier, works of art on paper are susceptible to chemical damage. Prolonged contact with acidic materials is a common source of chemical damage to paper, causing discoloration and embrittlement over time. Therefore, choice of housing and display materials is critical.
- House works in lignin-free and acid-free mats or folders with a minimum pH of 7.0.
- Store flat (face up) in acid-free Solander boxes, or in powder-coated steel or anodized aluminum drawers; exposed wood drawers can transmit acidity and resins that are harmful to paper.
- Protect the surface of artworks with acid-free interleaving paper.
- Avoid storing works with staples and paper clips as they damage paper.
Matting artwork with 100% cotton mat board provides protection, making it easier to handle, store, and when framed, separates an artwork from the glazing, while also adding to its presentation. Mat board, is available in different thicknesses (2 ply, 4 ply, 8 ply, etc.) and colors. Inferior mat board containing wood pulp can become chemically unstable, increasing in acidity over time, and damaging paper adjacent to it. Caution should be taken against using mat board that is finished or faced on either side with a high-quality cotton paper, but manufactured with poor quality core materials. Even if the side of the mat that touches the artwork is made of acid-free paper, the acidic core material will degrade and through prolonged exposure, deteriorate the artwork and promote mat burn—an orange-brown linear stain on a print or drawing caused by the interior cut edge of an acidic window mat. Often an alkaline reserve, or buffer, is added to mat board to render it chemically stable and neutralize acidity in the atmosphere, adjacent materials, or in the artwork itself. Some colorants and printing processes are alkaline sensitive and may be adversely affected by the introduction of buffers, particularly if they exceed a pH of 7.5. In these cases, non-buffered or neutral pH materials would be preferable.
An artwork should be protected on both sides, with a window mat and a back mat made of 100% cotton. The back mat can be the same ply or a thicker ply than the window mat; a board that is thinner than the window mat does not give adequate support. The window mat is attached to the back mat along the long edge (either left if vertical or top if horizontal) so that the window mat can be opened like a book. The artwork is attached to the back mat with a material that is lighter in weight than the artwork, and if necessary, can be easily removed. The print or drawing should be adhered in a way that allows it to naturally expand and contract without buckling.
Japanese paper hinges and wheat starch paste are the most common means to attach an artwork to a back mat because they are strong, stable, and reversible (meaning they can be removed from the artwork). Half of each paper hinge is pasted to the reverse side of the artwork along the top edge near the corners; the other half of each hinge is pasted to the back mat. Hinging near the top corners allows the artwork to move freely in response to environmental changes; paper can be damaged if attached at too many points or glued directly to the back mat. Works may also be secured to their back mat with acid-free paper or polyester photo corners. Avoid using linen tape and never attach pressure-sensitive tapes (transparent self-adhesive tape or masking tape), dry-mount tissue, or other commercial glues and adhesives to works of art, as such material often can discolor and become difficult to remove without causing further damage to the artwork. Many of the resources listed below include illustrations and detailed instructions for matting prints and drawings.
Framing matted artwork provides optimum protection from physical and environmental damage and, like mat board, adds to the aesthetic of the artwork. The most basic elements of a frame include the glazing, backing board, and the decorative molding—all of which surround the matted artwork. Additional materials, such as tapes or film barriers, are sometimes used for enhanced protection.
Glazing, made of either glass or acrylic, not only protects art from surface damage and exposure to dirt and dust, it can also be manufactured to filter out harmful ultraviolet (UV) wavelengths. Many factors affect what type of glazing to choose—budget, object’s size, purpose—but a few considerations are important to keep in mind. UV-filtering laminated glass (a type of safety glass) is preferred to standard UV-filtering glass as the later could shatter, and cut and puncture artwork. Standard UV-filtering acrylic typically generates a static charge that disrupts the adhesion of powdery media, and therefore, is not recommended for framing pastels, as well as some chalk and charcoal drawings. In this case, anti-static glazing, such as Tru Vue Optium Acrylic or UV-filtering laminated glass, should be used. Avoid framing works directly against the glazing as media can transfer to it and surface alterations can develop. Additionally, moisture can condense on the interior surface of the glazing, resulting in mold growth and damage to the work of art. A window mat separates the artwork from the glazing. Greater depth can be achieved between the work of art and the glazing by using a thick mat, such as 8-ply mat board, or by incorporating a spacer within the frame.
The backing board should be chemically stable and rigid enough to hold the contents within the frame without bowing, such as corrugated paperboard that is lignin-free and acid-free or corrugated polypropylene board (e.g., Coroplast). The gap between the backing board and the frame can be closed with frame sealing tape made of acid-free foil laminate.
To further minimize the effects of pollutants and changes in relative humidity, matted works can be framed with a layer of impermeable material such as polyester film (e.g., Mylar), or plastic-aluminum laminate (e.g., Marvelseal), that is placed either between the back mat and backing board, or outside the backing board. Particularly vulnerable works, such as Japanese woodblock prints, works on brittle paper, or works with friable or sensitive media, may be housed in a stabilized humidity control package, sometimes called passe-partout. Note that artworks on particularly acidic supports or papers should not be sealed in any enclosure.
Maintaining an inventory of your art collection can be helpful in the event of an unexpected disaster. At a minimum, an inventory should include the artist’s name, title or description of the image, date or approximate date of artwork, medium, and dimensions for each artwork. Original purchase receipts can be helpful in identifying works and contributing to their valuation and provenance. Photographs of the artwork, current insurance values, and condition records are also extremely beneficial to the long term care of your collections.
RESOURCES FOR CARE OF PRINTS AND DRAWINGS
American Institute for Conservation of Historic and Artistic Works. Caring for Your Treasures: Documents and Art on Paper. Washington, DC: American Institute for Conservation of Historic and Artistic Works, 2018.
Clapp, Anne F. Curatorial Care of Works on Paper: Basic Procedures for Paper Preservation. Oberlin, OH: Intermuseum Conservation Association, 1973. archive.org/details/curatorialcare00clap
———. Curatorial Care of Works on Paper: Basic Procedures for Paper Preservation. New York: Nick Lyons Books, 1987. (illustrated edition)
Dolloff, Francis W., and Roy Perkinson. How to Care for Works of Art on Paper. Boston: Museum of Fine Arts, 1979.
Ellis, Margaret Holben. The Care of Prints and Drawings. Lanham, MD: Rowman & Littlefield, 2017.
Guild, Sherry. “Caring for paper objects.” Preventive conservation guidelines for collections online resource. Canadian Conservation Institute, Dec. 14, 2018: https://www.canada.ca/en/conservation-institute/services/preventive-conservation/guidelines-collections/paper-objects.html
Library of Congress. “Care, Handling, and Storage of Works on Paper.” Library of Congress: Preservation. 2018. www.loc.gov/preservation/care/paper.html
Northeast Document Conservation Center, “NEDCC Preservation Leaflets,” Northeast Document Conservation Center. https://www.nedcc.org/free-resources/preservation-leaflets/overview
Schultz, Arthur W., Huntington T. Block, et al. Caring for Your Collections. New York: Harry N. Abrams, Inc. and National Committee to Save America’s Cultural Collections, 1992.
Zigrosser, Carl, and Christa M. Gaehde. A Guide to the Collecting and Care of Original Prints. New York: Crown Publishers and Print Council of America, 1965. https://archive.org/details/guidetocollectin00carl
American Institute for Conservation of Historic and Artistic Works. Caring for Your Treasures: Matting and Framing. Washington, DC: American Institute for Conservation of Historic and Artistic Works, 2018. www.conservation-us.org/docs/default-source/public-relations/mattingandframing.pdf
Blyth-Hill, Victoria. “Passepartout [sic] (Stabilized Humidity Control Package).” The Book and Paper Group Annual 10 (1991): 29–33. cool.conservation-us.org/coolaic/sg/bpg/annual/v10/bp10-03.html
Hatchfield, Pamela B. Pollutants in the Museum Environment: Practical Strategies for Problem Solving in Design, Exhibition, and Storage. London: Archetype Publications, Ltd., 2002.
James, Carlo, et al. Old Master Prints and Drawings: A Guide to Preservation and Conservation. Translated and edited by Marjorie B. Cohn. Amsterdam: Amsterdam University Press, 1997.
Northeast Document Conservation Center. “4.9 Storage Solutions for Oversized Paper Artifacts.” Preservation Leaflet. Andover, MA: Northeast Document Conservation Center, 1999.
Norton, Chail, and Soko Furuhata. “Passepartout [sic]: Properties, Performance, Packing: Reevaluation of an Environmental Package for Traveling Works on Paper.” The Book and Paper Group Annual 25 (2006): 29–33. cool.conservation-us.org/coolaic/sg/bpg/annual/v25/bp25-07.pdf
Phibbs, Hugh. “Preservation Matting for Works of Art on Paper.” Picture Framing Magazine (February Supplement, 1997): 4–30. www.loc.gov/preservation/care/Phibbs.pdf
Rayner, Judith, Joanna M. Kosek, and Birthe Christensen, eds. Art on Paper: Mounting and Housing. London: Archetype Publications, in association with the British Museum, 2018.
Ritzenthaler, Mary Lynn. Preserving Archives and Manuscripts. SAA Archival Fundamentals Series. Chicago: Society of American Archivists, 1993. babel.hathitrust.org/cgi/pt?id=mdp.39015032925144;view=2up;seq=1
Smith, Merrily A. Matting and Hinging of Works of Art on Paper. Washington, D.C.: Library of Congress, National Preservation Program, 1981: www.loc.gov/preservation/care/SmithBrown.PDF
Tétreault, Jean. Airborne Pollutants in Museums, Galleries, and Archives: Risk Strategies, and Preservation Management. Ottawa: Canadian Conservation Institute, 2003.
Thickett, D., and L. R. Lee. Selection of Materials for the Storage or Display of Museum Objects. The British Museum Occasional Paper 111 (2004). www.britishmuseum.org/pdf/OP_111%20selection_of_materials_for_the_storage_or_display_of_museum_objects.pdf
Wright, Joan, ed. Guidelines for Lending Works of Art on Paper. With new foreword by James A. Ganz. N.p.: Print Council of America, 2015. printcouncil.org/wp-content/uploads/2016/10/FINAL_PCA_Guidelines_for_Lending.pdf
Kimberly Nichols is a paper conservator who has worked for the Art Institute of Chicago and the Museum of Fine Arts, Boston. She received her Master of Arts and certificate of advanced study in art conservation from Buffalo State College in New York. Debora Wood is an independent curator and specialist in prints and drawings, formerly of the Art Institute of Chicago, Northwestern University’s Block Museum of Art, and other institutions. The authors express their gratitude to Marilyn Symmes, Roy Perkinson, Joan Wright, the Print Council of America Board of Directors, and Print Council President Shelley R. Langdale for their review and guidance of this document.
“Care of Art on Paper” was posted on June 1, 2019.