Preventive Care of Graphic Art on Paper - Cornell University Library

PREVENTIVE CARE OF GRAPHIC ART ON PAPER

William Sharp, The Great Water Lily of America, 1854, chromolithograph. Rare and Manuscript Collections, Cornell University Library (Photograph by Tatyana Petukhova)

Cornell University Library Department of Preservation and Conservation Ithaca, NY 2001 1

PREVENTIVE CARE OF GRAPHIC ART ON PAPER The goal of preventive care of work on paper is to employ a holistic approach to stabilize its condition and mitigate the process of deterioration and damage through: improvement of environmental conditions, proper exhibition, handling, and storage, and other procedures without chemical or physical invasion into the artifact itself. This brochure is intended for those interested in preventive care of graphic art on paper such as prints and drawings. It describes structural elements of works on paper, provides information on the development of artist’s materials with emphasis on their chemical stability, and, most of all, presents solutions for principal agents of damage and deterioration. The information given in this brochure on preventive care is relevant today; however, with rapid development of the conservation field it might be altered in the future.

Graphic Art on Paper The word “graphic” derives from the Greek word “grapho,” which means to write or draw. “The class of visual arts in which lines, marks, or characters are impressed on a flat surface, usually paper. These include drawing, engraving, etching, lithography…” —The Pocket Dictionary of Art Terms, published by the NY Graphic Society

The physical structure of works of art on paper consists of an image and a paper support, both of which are integrated one into another. Physical and chemical stability and compatibility of the materials chosen by the artist are essential for longevity of the work. For example, dry pastel medium will be better retained in the grains of a textured surface such as Not (medium texture) or Rough (very textured) than on a smooth paper surface. Since paper is clearly an integral part of the artistic expression, the properties of paper such as color, texture, and absorbency are very important to consider. Along with

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aesthetic qualities, artists should also be concerned with the properties of paper, which could affect the longevity of their work.

Image Drawing and printing create a visual image through application of a colorant by three principal techniques:
Dry method, when colorant in dry form (pastel, sanguine) is used
Application of colorant in liquid form (India ink, watercolor)
Printing, where pressure is applied to transfer the printing ink from the inked intermediate surface (wooden block, lithographic stone, metal plate) to paper. Drawing and Painting Human expression through visual images has been traced to the Paleolithic period. The most notable works of Paleolithic art are animal figure paintings on the surfaces of caves at Altamira in northern Spain (10,000 BC.), and the painted images of animals of the Lascaux cave in France (15,000 BC). Besides the red earth pigment, which already had been known in the early Paleolithic period (used for flesh decoration, e.g. tattoos), other pigments such as hematite (hematite iron), sandy ochers, manganese-oxide browns and black, and calcite white were introduced to create these remarkable paintings. Pigments are insoluble in binding media such as oil and acrylic. Pigment particles of pure color could be either organic (indigo, madder) or inorganic (ochre, burnt sienna) in origin. Inorganic pigments are generally chemically stable whereas, organic pigments are more reactive and therefore more sensitive to the ambient environment. The evolution of colorants progressed with the appearance of new supports (papyrus, parchment, and paper) for painting, drawing, and writing. In ancient Egypt, for example, black (soot, water, and gum arabic) and red (Cinnabar) inks were used for writing on papyrus; in the Middle Ages a variety of animal, vegetable, and mineral colorants were available — permanent mineral pigments were mostly used by painters. Over the centuries the artist’s palette has changed in accor-

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dance with the development of color manufacture. In the time of the Industrial Revolution, many pigments produced were chemically unstable and toxic (e.g., lead white). Aniline colorants were introduced circa 1860 and made another dramatic impact on artist’s materials via industrial chemistry. Bright artificial aniline colorants were chemically unstable and poorly retained their original vibrancy. These changes affected dramatically the sphere of painting and drawing, and to some degree, printmaking. Today permanent and inferior colorants are readily available. Artists should proceed cautiously in choosing their materials. (For guidance in choosing materials, see School of Color publications at: www.schoolofcolor.com.) Printmaking Paintings, because of their labor-intensiveness and material costs, have always been expensive and limited to the province of wealthy nobles and aristocrats. The printmaking process was most likely developed as an alternative, less expensive medium, to meet the growing appreciation and desire for art works. Several identical impressions can be printed from the same surface, allowing prints to be produced in quantity and making them relatively inexpensive. The earliest prints were woodcuts of religious pictures and playing cards. They were produced at the end of the 14th century in Germany and the Netherlands. As the popularity of prints grew, a wide variety of printmaking techniques were developed. There are diverse printmaking processes existing today; most of them fall into four major categories: 1) Relief Process, 2) Intaglio Process, 3) Planographic Process, and 4) Stencil Process. Relief Process In this process, the lines of a design are drawn on a surface, often a wooden block or a metal plate. The areas to be left blank are cut out away with a knife or chisel, exposing the raised areas. Sticky ink that will not run off the raised surface is applied, and, when the paper is pressed against this surface, the printed image is created. This process is used for woodcut, linocut, and metalcut. Intaglio Process In this process, the lines to be printed are incised into a metal plate by creating grooves and hollows in the plate. These indentations are produced either by a hand tool (engraving) or

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by acid (etching) which eats into the metal. The plate is often warmed to expand the incised areas intended for the ink. The ink is also pushed deeper into the grooves with a dabber. Residues of the ink are wiped clean from the raised surface and paper is placed on the plate. Then the paper is covered with a wool blanket and the whole sandwich is passed through a two-cylinder press. Under substantial pressure, the paper is pushed into the recessed areas to bind with the ink and create the image.

Egbert van Panderen, Saint Avgustinus, 17th century, Intaglio process print, private collection.

Planographic Process In this process, the image produced is neither raised above or lowered below the paper surface. The process is based on the natural ability of water to repel grease. First, the design is drawn with a greasy pencil on the surface — traditionally litho stone. Next, the portion of the surface that is to remain blank is moistened with water. Then sticky ink is applied to the surface; it attaches to the oily design and is repelled by the moistened areas of the surface. When paper is pressed against this inked surface, the image is made. Lithographs are produced by this method. Stencil Process In this method, the design is drawn on a surface and then cut out. The surface then is placed over the paper support, covering the areas to remain blank. The image then is created by application of the color through the cutout part of the design. Silkscreen printing is an example of the stencil process. However, work made by the stencil printing method where colorant is applied by painting through cut-outs is not considered a true printing method in the traditional sense. Various processes for generating images have been developed. Photomechanical processes, such as collotype, photogravure, and halftone, were developed in the 19th and early 20th

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century. Works generated by ink jet, laser printing, and photocopying also belong to the print family.

Paper Paper has played an important role through the history of civilization as a traditional support for writing, printing, and drawing. It is a structure for dissemination of knowledge and an excellent means for artistic expression. Prior to the invention of paper, other materials such as papyrus, wooden tablets, and parchment were used. The invention of papermaking is attributed to Ts’ai Lun in 105 AD. Sheets of paper made by Ts’ai Lun from beaten mulberry and other barks, fishing nets, hemp, and rags were far superior to the earliest paper made from tangled silk in China around 200 BC. Composition Paper is usually made in a form of a pliable sheet of vegetable fibers intertwined in a compact web. The best quality paper is produced from plants, cells of which have high content of cellulose. Cellulose is a complex polymeric (long chained) carbohydrate consisting of D-glucose molecules linked together. Cotton and linen, for example, are mainly composed of pure cellulose. Prior to 1840, when woodpulp was introduced as a raw papermaking material, most Western papers were made from linen and cotton rags. These earlier papers were resistant to deterioration and some of them have survived This image is printed on Western handmade, laid paper with the watermark of a paper mill. By placing the artifact on a light table, visibility of the papermaking features of the paper is enhanced. In traditional Western papermaking, two types of paper pattern can be produced: laid and wove. All paper made in Europe before the end of the 18th century was laid. The pale laid lines and the chain (linking) lines of the laid paper are formed according with the wire-mesh pattern of the mould screen. Wove paper is made on wove wire-mesh which resembles the pattern of the woven fabric.

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for centuries. Today the following raw materials are used for making paper:
Soft and hard wood: pine, oak, eucalyptus, etc.
Bast: mitsumata, gampi, hemp, jute, flax, kenaf, etc.
Grasses: straw, bamboo, reed, esparto, etc.
Leaf: manila, sisal, henequen, etc.
Seed hair: cotton Process The process of making paper by hand has changed little since 105 AD, when its invention was first recorded. All paper until the 19th century was made by hand (handmade paper). To produce handmade paper, geographically available raw plant material (e.g. mitsumata, gampi, kozo in Japan) is macerated in water, boiled, and beaten until the individual fibers are separated. Paper is formed by suspension of water mixed with fibers scooped into a mould, which resembles a sieved bottom tray. While there is still water in the mould, the vatman gently vibrates the mould in four different directions to produce a fine, evenly formed fiber deposit. When water passes through the sieve-like screen, it finally leaves a felted fiber deposit at the bottom of the mould. This deposit after pressing, drying, and finishing becomes a sheet of handmade paper. Types of paper Besides Handmade paper, two other categories of making paper presently exist: mouldmade and machinemade. Mouldmade paper is usually produced from good quality fibers, rich in cellulose, by a cylinder-mould machine. This machine produces a continuous paper web, which is later cut to appropriate sizes. Along with the handmade, mouldmade paper is recommended for use by artists. The third papermaking category is machinemade paper, which is produced by a Fourdrinier machine from fiber extracted from wood. Wood fiber contains lignin (a complex polymeric substance responsible for the strength of wood) which becomes very acidic in a wood fiber paper if it is not chemically removed. Old newspaper that has changed color to yellow or brown and has became extremely brittle is an example of the lignin effect on paper. Fortunately this substance can be removed from the wood fiber, e.g. machinemade ‘permanent’ paper. This paper is often used in publishing of books. There are three main types of machinemade paper: mechanical pulp, chemical pulp or

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‘woodfree’, and machinemade ‘permanent.’ Mechanical and chemical pulp papers are not recommended for use by artists since they might contain lignin, chemical residue, etc. Although ‘permanent’ paper is popular among artists, their first choice should be handmade and mouldmade papers, which are long-fibered and rich in pure cellulose. Choosing the paper When making a paper choice with preservation concerns in mind, the following should be considered:
If the paper was tested to satisfy the ANSI (USA) for Permanent Paper, or if it passed accelerated aging tests (e.g. Photographic Activity Test or PAT)?
Does it contain ‘rag’ fiber (ideal) or is it entirely chemical woodpulp?
Is the paper acid and lignin free?
Does it have a neutral pH (7) or higher?
Does it contain alkaline reserves such as calcium carbonate?

Causes and Prevention of Deterioration “To guess is cheap. To guess wrong is expensive.” —Old Chinese proverb

Some works on paper are more susceptible to deterioration than others. The nature of the materials from which they are made conditions their gradual decay. The goal of preventive care is to stabilize the artifact’s condition and to slow down the process of deterioration. Many factors contribute to artifact deterioration, these are the principle causes: Intrinsic Flaws Inappropriate Environment Mistreatment by Humans Intrinsic Flaws Excessive acidity is very harmful to paper based materials. It breaks and weakens the molecular chain of cellulose. Acidity can occur from within the paper itself, as well as, from exposure to an unfavorable environment. One of the main causes of acidity is papermaker’s alum (hydrated aluminium sulphate), which was introduced as a

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new sizing agent circa 1807. Consequently, dramatic changes in paper quality occurred. Lignin-complex compound which is present in wood pulp paper is another contributor of acidity. Some wood-pulp papers contain lignin, other papers are lignin free. Papers such as chemical pulp, and machinemade ‘permanent’ are lignin free. Machinemade mechanical pulp paper contains lignin. Other potential sources of acidity derive from chemical residues left in the paper from bleaching and pulping. Heavy metals, iron and copper in particular, deposited in paper fibers from papermaking machinery, could also accelerate the oxidation process and cause severe damage to paper artifacts. Besides those mentioned above, there are other contributors to rapid deterioration of works of art on paper—most importantly the use of incompatible materials (e.g. charcoal drawing on tracing paper) and poor quality colorants (e.g. 19th century Windsor & Newton synthetic colorants from chemically unstable dyes). Solutions Preservation of graphic art on paper ideally starts with the artist’s concern with the longevity of materials from which the work on paper is executed. Compatible, chemically stable artist’s materials (e.g. ASTM—American Society of Testing and Materials—Lightfast colorants I-excellent, or II-very good) will dramatically increase the life span of the work. Properly chosen colorants will keep their freshness and vitality; chemically stable ‘rag’ paper supports remain strong and pliable over a long period of time. Careful consideration should be taken by artists prior to creating their work. Some considerations are the following:


Is the type of paper chosen for the medium the most suitable (see Silvie Turner, Which Paper?)? For example, a Not (not rough, medium textured) or Rough mouldmade or handmade paper with some degree of sizing is more appropriate for a watercolor drawing than the Hot Press (H.P.) paper.

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Are the colorants (pigments and dyes) and the paper chemically stable? Pigments with ASTM Lightfastness 1 are excellent in their resistance to color change due to light and unfavor able environmental conditions (e.g., impurities in the atmosphere) exposure. Lightfastness rated IV means that this pigment will rapidly fade.

Useful references and web site addresses on the stability of artist’s materials are provided at the end of the brochure.

Inappropriate Environment Lighting Paper artifacts exposed to visible and ultraviolet (UV) light will degrade through chemical reactions within the materials. For example, fugitive dyes and organic pigments will fade, and paper will exhibit signs of discoloration, yellowing, or darkening. UV radiation emitted by the sun and fluorescent bulbs is particularly harmful to works of art on paper. The higher the intensity of light and longer the duration of exposure, the more damage done to the artifact. Some paper artifacts, such as prints with stable carbon ink, are more resistant to these conditions than others. Solutions Do not expose works on paper to direct sunlight. Under this condition, Japanese prints, and watercolors will likely degrade. Use UV-absorbing glass or an UV-3 filter Plexiglas for framing. Protect works on paper with UV-absorbing sleeves to shield fluorescent bulbs (Gaylord, University Products), and filters over windows. When possible, reduce illumination time. Humidity and Temperature Excessive humidity, dryness, and heat, as well as radical fluctuation in temperature and relative humidity (RH) cause damage to works on paper by accelerating the aging and decomposition processes. For example, high degree of RH softens the gelatin sizing in paper, which attracts particulate matter from the atmosphere and promotes bacterial and fungal

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growth. All the above factors could irreversibly damage works on paper. Solutions Along with works on paper, other artifacts (such as paintings or objects) are stored and exhibited. RH and Temperature (T) requirements for different types of objects vary, there are some recommendations, however, that could benefit all types of artifacts.
Keep RH constant and ambient T, ideally, within 60-72° F (20-21° C).
Do not store artifacts, and particularly works on paper, in basements or attics, where they might be exposed to extreme environmental conditions.
Avoid bathrooms and fireplaces for hanging works on paper in particular.
Walls near frequently opened windows and doors are not appropriate for display of sensitive artifacts. Pollution Atmospheric pollution (sulfur dioxide, nitrogen oxides, ozone, etc.) advances chemical reactions of colorants (e.g., fading of synthetic dyes), and degrades cellulose (paper) and proteins (parchment). Particulates such as dust and soot can stain organic materials. Harmful organic acids are produced from wood and wood-pulp products such as wooden cabinets, frames, and wood-pulp boards. These acids can migrate to works on paper causing often severe discoloration and structural weakness. Solutions Activated carbon filters are recommended for removal of gaseous pollution, and HEPA filters are useful for particulate matter reduction. Wood and wood-pulp backings should never be used in framing works on paper. If wood framing is chosen, seal the inner perimeter of the frame with MicroChamber emulsion, (Conservation Resources International, L.L.C.), or water-soluble polyurethane will provide a barrier and prevent unnecessary deterioration. Avoid wooden cabinets for storage. Chemically stable flat file storage units coated with baked enamel (University Products, Inc.) safely accommodate a substantial collection. For storage of small collections of works on paper, archival drop-front

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boxes (made from acid-free, lignin-free, pH 7-8.5 with calcium carbonate buffer board) are appropriate (Gaylord, The Hollinger Corporation). For details on matting materials see the Matting and Storage section of this brochure. Microbiological and Biological Agents Acidic environment, excessive moisture, poor air circulation, and heat are the most prominent conditions promoting bacterial and fungal growth in works on paper. During the metabolic process, fungi, for example, not only physically destroy organic materials, but also discolor them by producing acids. One problem may compound another. Insect pests, such as beetles, silverfish, and mites are attracted by natural adhesives, dust, and fungi, as well as by cellulose (paper). They can cause irreversible loss to materials. If the works on paper are improperly stored, rodents such as mice can also be a problem. They might find proteins and starches in works on paper quite alluring. Mistreatment by Humans Unlike books, which are made with protective covers, works on paper are fragile by nature and therefore can be easily damaged. Improper handling, matting, and storage techniques contribute to their tearing, breaking, and other problems, which often can be easily avoided. Unprofessional attempts to solve the problem by repairing, lining, hinging and matting may become fatal to the work itself. For example, works on paper repaired or hinged with pressure-sensitive tape, such as Scotch tape, will often exhibit severe brittleness and discoloration over time. Salvage of the problem by a professional conservator might take hours of work and the condition might not necessarily be reversed. Pressure-sensitive tape was introduced in the 1890s and has become widely used. The adhesive in the tape may consist of synthetic or natural rubber, or chemically unstable acrylic polymers. Acid migration from inferior quality matting materials presents another example of mistreatment.

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Solutions Paper artifacts should be properly handled and supported with a rigid and chemically stable structure during their transport, — even from one surface to another. The minimum advised practice for handling consists of the following:
Wash hands or wear clean cotton gloves (Gaylord, University Products) prior to handling as residue of oil and soil from the hands may lead to staining of the materials.
Handle the artifact with both hands and carry on a rigid and smooth, chemically stable support such as archival corrugated board.

Matting and Storage Matting and hinging of works on paper require skill and the use of chemically stable materials. In a professional setting (e.g. conservation laboratory), properly prepared starch paste and Japanese Kozo tissue are usually used to hinge a paper artifact to the backing mount board. Conservation or MicroChamber mount boards are used for the mat window and the backing mount board. When framed, another backing board such as archival corrugated, Coroplast corrugated, or acid-free Fome-Cor is placed behind the backing mount board to complete the framing. Drawing on paper with dry soft media such as pastel, charcoal or sanguine produce a sensitive paper artifact, which needs special handling and storage. To minimize loss to the image, handle the artifact from the verso without touching the surface; store these types of works matted and framed. The surface of the drawing should never touch the glass or Plexiglas of the frame. Japanese prints are among the most sensitive works; they should never be exposed to extreme environmental conditions such as direct sunlight under which the colors will change or fade completely. The colorants that are generally used to print these works are sensitive not only to acidity (pH7) as well. For matting and storage of these works archival (free of acid, lignin, and sulfur; PAT tested) storage materials with pH 7 (neutral) are recommended. The same requirements are most appropriate for prints colored (handcolored) with dyes or other chemically unstable colorants.

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Other types of prints and drawings can be matted, or stored in folders. Archival Conservation or MicroChamber mount boards are the best choice for matting. Archival Map Folder Stock, MicroChamber paper, PermaLife Bond paper, and Apollo paper (Light Impressions) are appropriate materials for making folders in which works on paper could also be stored. Placed in folders, prints and drawings should be stored in Drop Front or Clamshell (for small works) boxes made of chemically stable boards. Tan lignin-free board boxes are recommended for storage of valuable works on paper. Another possibility for storage in boxes is to keep works on paper interleaved with archival interleaving papers. In case of an emergency seek professional assistance.

Proper storage of small works on paper. The artifacts are inserted in the Apollo paper enclosures and stored in the archival Clamshell box. (Cornell University Library Collection)

SOURCES Professional advice, referral, & conservation information: American Institute for Conservation of Historic & Artistic Works (AIC) 1717 K Street, NW Suite 200 Washington, DC 20006 (202) 452-9545 http://aic.stanford.edu

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FAIC Conservation Services Referral System http://aic.stanford.edu/faic/refer.html Department of Preservation & Conservation Cornell University Library 215 Olin Library Ithaca, NY 14853 (607) 255-9440 http://www.library.cornell.edu/preservation [email protected]

Suppliers: Conservation Resources International, LLC 800-H Forbes Place Springfield, Virginia 22151 (800) 634-6932 [email protected] www.conservationresources.com The Michael Wilcox School of Color 25 Mauchly # 328 Irvine, CA 92618 (888)-7Wilcox http://www.schoolofcolor.com/index.html University Products 517 Main Street, PO Box 101 Holyoke, Massachusetts 01040-0101 (800) 628-1912 [email protected] www.universityproducts.com Gaylord Bros. PO Box 4901 Syracuse, NY 13221-4901 (800) 448-6160 [email protected] http://www.gaylord.com/archival

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Light Impressions PO Box 22708 Rochester, NY 14692-2708 (800) 828-6216 www.lightimpressionsdirect.com The Hollinger Corporation PO Box 8360 Frederickburg, VA 22404-8360 (800) 634-0491 [email protected] www.hollingercorp.com

Selected Reading Appelbaum, Barbara. Guide to Environmental Protection of Collections. New York: Sound View Press, 1991 Clapp, Anne F. Curatorial Care of Works of Art on Paper. Intermuseum Conservation Association, third ed., 1987 Delamare, François and Guineau, Bernard. Colors The History of Dyes and Pigments. New York: Harry N. Abrams, Inc., 2000 Gascoigne, Bamber. How to Identify Prints. London: Thames and Hudson, 1980 Griffiths, Antony. Prints and Printmaking; An Introduction to the History and Techniques. 1980 Shelley, Marjorie. The Care and Handling of Art Objects. Practices in the Metropolitan Museum of Art. New York: The Metropolitan Museum of Art, Revised ed., 1992 Smith, Ray. The Artist’s Handbook. New York: Alfred A. Knopf, 1992 Turner, Silvie. Which Paper ? London: BAS Printers Limited, 1991 Wilkinson, Norman B. Papermaking in America. Greenville, Delaware: The Hagley Museum, 1975

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