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IDENTIFYING THE REAL THING
(Prepared by D. van der Reyden of SCMRE, for School for Scanning, Sponsored by the National Park Service and Managed by the Northeast Document Conservation Center, September 11-13, 1996, New York City)
INTRODUCTION
THE POWER OF "THE REAL THING"
HOW TO IDENTIFY "THE REAL THING"
BIBLIOGRAPHY
INTRODUCTION
People often go to museums, libraries and archives to see "the real thing." But "the real thing" can be "seen" in many ways. Appearance can be observed on exhibit or on-line, or measured in a laboratory. However, materials and technology can be revealed only by stylistic, historical and scientific analysis of "the real thing." The findings of these various types of analysis by museum specialists (such as curators, historians, scientists, archivists, conservators and other experts) can then be communicated to or "seen" by various audiences, ranging from the general public to scholars, visiting on site or working on-line. The media through which findings are "seen" can include exhibits, publications, computer programs, lectures and videos, produced with the aid of other museum professionals (specializing in exhibition, registration, publication, public relations, education, research, collections management and computer science). But, consider this: when you look at an image on exhibition or on-line, do you know if that object is "real"? How can you tell? Why does it matter?
THE POWER OF "THE REAL THING"
Why is "the real thing" so important to people? Objects are valued not only for their appearance, but also for their tremendous symbolic power. Any object can have symbolic and visual power. However, only "the real thing" contains the evidence to support its symbolic and visual importance. Evidential, artifactual, value is dependent on the material composition of the object. Reconciling the symbolic, visual, artifactual and evidential value of "the real thing" requires the convergence of stylistic, historical and scientific analysis. Such expertise is often provided by the collaboration of many experts found in museums like the Smithsonian.
What do people really see when they look at an object on exhibit, in a book or on- line? What they actually see is a virtual reality, based on the appearance of the real thing. The appearances of objects have tremendous power to alter the course of history and human lives. But mere superficial appearances can be misleading.
Consider, for instance, something as simple as a manuscript. In fact, consider three famous manuscripts: "Howard Hughes' Autobiography," "Hitler's Diary," and the Mormon Church's "Salamander Letter." What do these documents have in common? Each had the power to greatly influence issues of legal, historical or religious significance. Each had this power, if, that is, they were "the real thing". But as it turned out, each was actually proven to be fake. The truth however exacted a costly toll, including the loss of human lives.(1)
Take, for instance, the case of the "autobiography" of Howard Hughes. The reclusive millionaire Hughes supposedly broke his seclusion to dictate an autobiography to author Clifford Irving. Hughes later protested that he had not communicated with Irving, and lengthy litigation began. No less than three handwriting experts authenticated letters that Irving claimed were from Hughes. These experts attributed the letters to Hughes based on the "fact" that the size and the spacing of the words written in the letters were characteristic of the style of Hughes' own writing. The resulting long and expensive legal dispute might never have been settled, had not Irving finally confessed to forging the letters.
The case of the "autobiography" illustrates the legal importance of verifying "the real thing." The case of the "Hitler diaries" illustrates the potential power of objects to revise political and social history. In the early 1980's Newsweek magazine published a special report on "Hitler's 'Secret' Diaries: How they could rewrite history." The diaries were finally exposed as fakes; in part because some of the materials used to make them were not invented until after Hitler's death. Modern optical brighteners were detected in the paper when the pages were examined under special illumination (such as ultraviolet light). The binding of the diaries contained modern synthetic materials, identified when samples were examined under high powered magnification (such as a stereo or polarized light microscope).
One of history's most extreme cases of forged documents threatened to undermine one of the world's most powerful religions. The case of the "Freeman's Oath" and the "Salamander letter", resulted in the actual loss of life. In the mid-80's, a Utah dealer, Mark Hofmann, presented the Mormon Church with a series of documents, which if real would have greatly embarrassed the Church. As suspicion grew about the authenticity of the documents offered by Hofmann, he began to feel cornered. To protect himself, and provide a diversion, he resorted to murder, engineering the death of three people by blowing them up with home-made bombs. He eventually injured himself while transporting new bombs. When arrested, he ultimately confessed that he faked the documents; to make them appear authentic, he used historic paper and ink recipes. He claimed that he even artificially aged the documents by oxidizing them with hydrogen peroxide. This is what lead to his downfall and arrest in the first place. His creations had become suspect when examination, under high powered magnification (such as a stereomicroscope), revealed that the ink's medium of gum arabic was cracking in a strange manner, totally inconsistent with what would happen during "natural" aging.
HOW TO IDENTIFY "THE REAL THING"
How can you tell that an object is "the real thing"? Identifying "the real thing" requires looking beyond the mere superficial surface appearance of objects. Taking objects at "face value" can lead people to misunderstand or misrepresent the true value of objects. The legal, historic, social or scientific significance of objects depends on that object's being "the real thing". Although any object can have "symbolic value," only "the real thing" is worthy of its "symbolic value" by virtue of its evidential value. Evidential value can only be supported by full and accurate characterization of "the real thing." Characterizing objects such as a print or manuscripts can require the combined expertise of curators, historians, connoisseurs, archivists, conservators, and scientists. To determine whether an object is "the real thing," that object must be analyzed in many ways.(2) Three important ways to examine objects for authenticity, illustrated in Table 1, include:
to think in terms of the maker's intent: how details of the design's composition (space, light, form, and lines) are define; how the qualities of line and color are expressed; and how well-executed and characteristic of the maker the piece is. Take, for example, an original manuscript (i.e. written by hand) as compared to a forgery, also hand-written. Forensic experts note that original manuscripts generally have writing that shows speed, consistency, uniform strength, pressure and carelessness. There should be backflow of ink only where the ink crosses over letters or where a refill of newer ink might backflow into the lines of the old ink. Fiber alignment on the paper surface can indicate the direction of a stroke to confirm whether it is correct. Words would rarely have breaks within them, and they would begin and end with flying strokes. A forged manuscript, however, might show a slow, hesitating hand with uneven pressure and both bold and weak strokes of ink intermingled. Letters might be reworked, or show a tremor not associated with age or ill health. Words might be stopped in the middle and then completed, with a puddle of ink backflow at the juncture. Or the ink might feather in creases, indicating that the paper was creased before the ink was applied.
Stylistic analysis can be confirmed or countered by historic and scientific analysis.
Historical Analysis
To be "the real thing", an object must be made with materials and techniques consistent with the style of the object and the history of materials and techniques associated with the time and place of origin of the object. To illustrate, consider the history of paper making and media technology, which is in itself full of mystery and intrigue. An historical analysis of objects on paper would need to include information on
- Materials and Techniques of Paper Making
- Materials and Techniques of Media
Materials and Techniques of Paper Making:
Although the origin of paper is disputed, early Chinese history records that in the second century AD, the scribe Ts'ai Lun presented the Emperor with his invention of papermaking. This invention, an obvious improvement over cumbersome predecessors like cave walls, clay tablets and parchment, revolutionized the art and science of writing in a way not rivaled again until the invention of the printing press and the PC (both of which are still dependent on that ancient support, paper!). The secret of papermaking was stolen in subsequent battles, and was adopted, adapted and spread throughout Asia and Europe over the next dozen centuries.(4) Depending on the location, paper would be made using fibers derived from various indigenous plants. The type of fibers used (mulberry, cotton, or banana...) are one clue to identifying a paper's origin or date (Ill. 1). In the West, paper was often made from fermented cotton and linen rags (hence the name "rag paper"). Other ingredients, added to change the chemical and physical properties of paper, may also provide clues as to origin and date of a sheet. For instance, to keep ink from spreading out
on paper, ingredients like starches (rice, potato) or proteins (glue, gelatin) can be added to a pulp slurry or applied after a sheet is formed, to "size" paper. These sizing agents can also be used to identify origin and date, if they have not already degraded into oblivion with exposure to light, heat or moisture. The way the paper was made may also provide clues to dates. Paper making can be divided into two basic techniques:
- Hand-Made Paper
- Machine-Made Paper
Hand-Made Paper: Early paper was made by beaten plant fibers which were first dispersed in water. The fibers were then cast randomly upon a papermaking mold. Each mold consisted of a frame holding a porous screen. Mold types varied depending on their origin, but each imparted a characteristic impression on the sheet of paper. For instance, a paper made with a "laid and chain" mold (like fine "antique laid" writing paper) would have a pattern of a series of thin, parallel translucent lines (laid-lines) linked with occasional perpendicular lines marking the location of the "chain" stitches holding the screens' laid-lines in place. This configuration actually derives from early oriental mats (much like modern bamboo place mats). "Wove" paper has, instead of parallel lines, a weave impression imparted by fabric or wire mesh screens.
One common characteristic of true "hand-made" papers is a "deckled edge" where slippery paper fibers gather under the mold frame as water is dispelled. Another characteristic that can help determine the date and origin of papers is the "watermark," traditionally formed from a raised design on the mold, but which can be falsified by a "dandy roll" impression. Mold characteristics and finishing techniques can also affect surface texture. For instance, rough paper surface texture may be the result of the impression of the raised wires of the paper mold or the hairs of the felts used for couching. This gives paper its so called right side, (the felted side), and wrong side (the wire side which could cause skipping of the media). These don't have as much effect as the smooth surface induced by calendaring, which is caused by rolling over with a steel cylinder. This compressed effect can be distorted by the swelling of fibers following exposure to water. The paper might also be finished by a coating, which could be dissolved by water or solvents. Any coating can restrain a paper or be cracked by expansion and contraction of the paper fibers. Types of coatings would include the carbonate used for metalpoints, albumen coating on a photograph, or a gelatin glaze to increase the intensity of some colors, for instance in a Currier and Ives print, or a varnish on a paper map.
Machine-Made Paper: The industrial revolution of the early 19th century ushered in a revolution in papermaking, as demand and mechanization increased. "Machine- made" paper is cast upon moving belts, of sometimes enormous size, which can impart a distinct grain or machine direction as fibers aligned parallel to the direction the belt is moving. This in turn has a tremendous effect on the properties of strength and dimensional stability of paper, causing the paper to be easily torn or curled parallel to the grain. The strength of paper was further jeopardized in the 19th century by the use of highly acidic additives or ingredients, such as ground wood fibers (or mechanical pulp containing acidic lignin) and alum rosin size, both of which can cause paper to yellow and become brittle. Later, lignin in woodpulp could be dissolved out to make somewhat stronger chemical woodpulp. If sized with acid agents like alum rosin, as in notebook paper, such paper might yellow. But if sized
cause a piece to be misidentified. Silver point can be reconverted to its original appearance by exposure to hydrogen peroxide.
Ink, a term originally derived from encaustic by way of "inchiostro"(7) has often been used as a writing, painting and printing medium, although it is usually applied in thin washes rather than thick impasto. Ink traditionally has contained binders of oil, glue, gums, resins, and waxes mixed with pigments or dyes, particularly in modern "printer's ink". Some modern inks, developed for gravure, contain acrylics.(8) Inks can be both friable and soluble, especially as they age, leading to flaking and smudging. Iron gall ink has special problems owing to its acidity (from the oxidation of its iron component), which can in severe cases cause it to eat through the paper support. This can cause both loss of legibility because of strike- through, or actual loss of paper. Modern inks, and especially felt-tips, can be fugitive, fading in light. They also tend to be highly soluble. Inks low in carbon, like bistre, become invisible when examined under infrared illumination.
Painting Media: Ink can also be used as a painting media if applied in a wash of solvent. Painting media can be categorized in several ways, based on the composition of colorants and binders, such as tempera, gouache, watercolor, oil and acrylic. For example, gouache differs from water color in that it is an opaque medium, whereas water color is transparent. In watercolor the white or highlights come from the background paper, but in qouache the white is applied as a pigment. Gouache is sometimes used for impasto effects and this extra thickness causes a major problem with gouache media. It can crack, scratch, rub, abrade, etc. Some of these same problems may occur with tempera and acrylics. The above media, except for acrylics, can also be soluble in water. Oil paint is occasionally used on paper, and the problem here is twofold. The oil paint layer may be stronger than the paper and has a different expansion and contraction rate, and it can actually cause the paper to become acidic and brittle. Some examples of painting media commonly found on paper are described below.
Tempera is a generic term for any aqueous media that "tempers" or binds pigment with egg, glue, gum, or starch. Egg tempera, used primarily between the 10th and 15th centuries (when it replaced encaustic until superseded by oil paint) regained popularity in the 19th century. Egg tempera consists primarily of egg yolk, which is a natural emulsion containing a drying oil that can take up to a year to dry. It is not very flexible and can crack if thickly applied. Egg emulsified with oil is also used in tempera. Glue temperas use animal products such as casein (milk) and gelatin (skin, bones) and may have glycerine added to reduce cracking and formalin to reduce water solubility. Gum temperas use plant products (sap) and tend to be brittle if applied thickly. Gum arabic, used for tempera (emulsified with drying oils), gouache (made flexible with honey, sugar or glycerine) and watercolor, may require a preservative (halogenated or chlorinated phenols, boric acid, or sodium benzoate) and may be emulsified with oils and resins and mixed with other aqueous media. Starch, also derived from plants, can be used as a base for tempera emulsions. Egg- oil emulsions and casein temperas comprise most commercially produced temperas today since upon aging to a matt or semi-matt appearance they become insoluble in water. Those with oil emulsions can be thick and flexible, although they can develop hairline cracking and discolor with age. The use of temper was supplanted by gouache between the 16th and 18th centuries for illuminated manuscripts and miniatures.
Gouache, a generic term possibly derived from "gouazzo" or painting with glue size, typically has a gum arabic (acacia) or dextrin (starch) binder; a filler or white pigment to provide body and highlights, and a matt appearance upon drying. Gouache traditionally is susceptible to surface marring or cracking if applied thickly, and remains water soluble, unless as in modern times acrylic is added to make it abrasion and water resistant. Gouache is often confused with watercolor.
Watercolor differs from gouache in composition (having no white filler for body or highlights), in appearance (applied as a thin wash), and properties (less solubility and cracking after drying). Watercolor became established in the 18th century, used to illuminate books and manuscripts where the fugitive nature of such a lean medium would be protected. However, in the 19th century moist or semi-moist watercolor was made by adding glycerine, replacing sugar or honey which were added to improve flexibility and reduce cracking of cakes of watercolors; ox gall or other surfactant wetting agents may be added to reduce surface tension and improve flow. Student grade watercolors may contain dextrin rather than gum arabic and may have fillers. While watercolor remains soluble, often the appearance of a thin wash may not change since fine pigments penetrate and lodge within paper supports. Highlights are created by the reflection of the paper.(9)
Printing Media: Paint and ink have traditionally been used as print media. The categories of prints are based on in how the media is applied. Printing is a transfer process; media is transferred from one substrate to another substrate. The transfer methods vary. There are several major categories of prints: relief, intaglio, planographic, stencil, and photomechanical.
Relief prints are made by carving away areas of a printing block, usually wooden, to leave raised areas that carry the ink. When the block is placed in contact with a piece of paper and pressed or rubbed, the ink is pressed into the paper, sometimes actually indenting or impressing the paper slightly. This is especially apparent in Japanese woodblock prints or in letterpress prints found in early broadsides and newspapers. The major problem with relief prints is that this distinct impression around the inked areas, evidence of relief techniques, could be flatten or lost if improperly cared for or treated.
Intaglio prints are made by incising a plate, usually metal, by any of several processes. The incisions are filled with ink, and the plate is wipe so that the surface is clean. The plate is then inverted onto a damp piece of paper and run through a press to force ink to sit on top of the paper. As a result, there is an ink build up on top of the paper, and a creased, stretched edge around the image edge known as a plate mark. The raised ink is sensitive to abrasion, and the plate mark may be weakened or flatten. Occasionally the platemark is even cut down or off by insensitive collectors or framers who aim for a better fit in an album or frame. The plate mark is one bit of evidence for the authenticity of an intaglio (although they can be forged as well) and so it should never be cut down. When matting, the platemark should always be displayed within the window of the overmat to expose all that the artist included in his design. Examples of intaglio prints are engravings, etchings, aquatint, drypoint, and mezzotints. Hand-colored prints, glazed prints or Chine colles can be particularly sensitive to fading from light or to surface marring or planar distortion from scratches, changing relative humidity, etc.
minerals (like oxides of carbon). Scientific analytical techniques can fall into several broad categories:
- Illumination
- Radiography
- Magnification
- Elemental Analysis
- Property Measurements
Illumination: An object's morphology (size, shape, texture) or optical properties (color, gloss, etc.) can be revealed through different wavelengths of light. The appearance of objects changes depending on the type of examination used. Wavelengths of light can illuminate, radiate, and irradiate objects. For example, light covered by red or yellow filters can reveal obscured writing under stains or in shadows. Monochrome sodium arc lamps suppress chromatic aberrations in order to penetrate glazes or overlayers to reveal signatures.
Visible light, the range that we see normally, shows different things about an object depending on whether it is aimed at the object from a spectral, raking or transmitted angle or direction. Spectral illumination, aimed directly (or spectrally) at objects shows us their color, shape and size, and reveals the presence of surface coatings or gloss. Raking light passes across the surface of the paper and dramatically reveals paper and media techniques and texture, and damages to the surface of the paper support (like cockling) and media (like flaking binder). Transmitted light, penetrating through paper, can show mold characteristics and watermarks, as well as tears or repairs. It can also provide other information about the type of mold on which the paper was cast, such as whether it was of a laid and chain type or wove type. By showing variations in densities, it displays fiber distribution, which indicates how the mold was move about during casting, and may also reveal damages and repairs not otherwise apparent.
Ultraviolet light, or "black light", reveals changes in elemental composition on the surface of objects because it causes specific fluorescence in materials depending on composition and age. Retouching, overpainting, varnishes, adhesives, and certain types of deterioration that might be invisible to the naked eye, like mold damage, can be detected and identified. UV fluorescence can sometimes make erased ink visible, can indicate overpainting or retouching, and can help identify different types of stains. For example, oil stains fluoresce orange, wax or starch can be bluish, or unsized paper deep purple. Different types of mold stains fluoresce differently, so even the kind of mold attack might be identified. Often mold attack is apparent in UV fluorescence even when it is completely invisible in normal light.
Infrared reflectography reveals carbon containing materials and otherwise "invisible" medium. Carbon media hidden under retouching, dirt, or other media can be seen, revealing underdrawings or pentimenti (literally changes in thought), or render other media invisible, such as bistre inks. Infrared illumination is especially useful with some drawing media. It can reveal covered signatures, or erased pencil and ink, or abraded or faded drawings. It can even penetrate paint layers to show primatura, or preliminary drawings.
Radiography: Radiography, using X-rays or more sensitive beta- and xero-rays, reveals changes in elemental density, so that the physical structure of an object may be articulated to show different layers, additions, elements, etc. For beta radiography, the paper object is placed between a radioactive plate and a piece of film for about 30 minutes. The film is then developed and produces a negative similar to an x-ray. This can provide documentation of watermarks, mold characteristics and other relative densities of the paper. Xero-radiography is more powerful for denser papers and can sometimes reveal layers of papers.
Magnification: In addition to illumination, magnification is a useful and relatively simple means of examining an object. A magnifying glass can often help to identify inclusions in paper or the type of media. However, sometimes much higher magnification is required.
Stereoscopic microscopes equipped with cool temperature fiber optic raking light and ring can clarify the nature of media by revealing the size and shape of particles, the location of the media (whether it rests above, on top of or within the surface fibers), the layers of media or coatings, the type of deterioration (such as live mold), and the extent of damage, retouching or repairs.
A Scanning Electron Microscope (SEM) provides a highly magnified view thousands of times the size of the sample and at a great depth field, to aid in morphological and topographical analysis of the sample.
paper. As indicated at the start of this section, the best results can come from collaborative curatorial efforts.
BIBLIOGRAPHY
Bruyn, J. "The Concept of School," Jaffé, H.L.C. et al, editors. Authentication in the Visual Arts, Amsterdam, l979, pp. 1-25.
Chatelain, Jean. Le Problems des Faux en Matiere Artistique. Etudes Secteur Culturel.
De Forest, P.R. et al. "Questioned Document Examination," Forensic Science: An Introduction to Criminalistics. McGraw-Hill, 1983. pp. 360-382.
Denier van der Gon, J.J. "Spontaneity in Motor Expression," Jaffé, H.L.C. et al, editors. Authentication in the Visual Arts, Amsterdam, l979, pp. 93-102.
Fay, S. et al. Hoax: The Inside Story of the Howard Hughes-Clifford Irving Affair, Viking Press, N.Y., l972.
Feller, R.L. "The Chemist as Detective: The technical Examination of Museum Objects," The Indicator, Dec. 1959. pp. 20-28.
Fleming, S.J. "An evaluation of Physico-chemical Approaches to Authentication," Jaffé, H.L.C. et al, editors. Authentication in the Visual Arts, Amsterdam, l979, pp. 103-134.
Hanna, Georgia A. "Art Forgery: The Role of the Document Examiner," Journal of Forensic Sciences, Vol. 37, No. 4, July 1992, pp. 1096-1114.
Harrison, W.R. Suspect Documents, Praeger, N.Y., l958.
Hughes, Robert. "Brilliant, But Not For Real," Time Magazine, May 7, 1990, pp. 118-
-----. "Sold," Time Magazine, November 27, 1989, pp. 60-65.
Kurz, Otto. Fakes, Dover Publications, New York, 1964 (?).
McCrone, W. "The Vinland Map," Analytical Chemistry, Vol. 60, No. 10, May 15, l988, pp. 1009-1019.
Naifeh, S. et al. The Mormon Murders, N.Y. l988.
Newman, R. "Authenticating your Collections," Caring for Your Collections, Abrams, New York, 1992, pp. 172-180.
Olin, J. "The Vinland Map: A Case Study," Proceedings: First Georgetown University Conference on Surface Analysis, printed by McChesney Duplicating Service, Inc., l970, pp. 25-39.
Osborn, A.S. Questioned Documents, Boyd Printing Co., N.Y., l946.
Perrig. A. "Authenticity Problems with Michelangelo: The Drawings on the Louvre sheet No. 685," Jaffé, H.L.C. et al, editors. Authentication in the Visual Arts, Amsterdam, l979, pp. 27-54.
Rendell, Kenneth W. "The Detection of Forgeries," Autographs and Manuscripts: A Collector's Guide, Schribner's, N.Y., l978. Berkeley, E., editor, pp. 73-91.
Rendell, Kenneth W. "Famous Forgers: Their Successes and Downfalls," Autographs and Manuscripts: A Collector's Guide, Schribner's, N.Y., l978. Berkeley, E., editor, pp. 93-99.
Werthmann, B. et al. "Naturwissenschaftliche Aspekte der Echtheitspruefung der songenannten "Hitler-Tagebuecher," Maltechnik-Restauro, Vol. 90, No. 94, l984, pp. 65-72.
ENDNOTES:
- For literature on these cases, see Rendell.
For the Hughes "autobiography", see Fay.
For Hitler's "diaries", see Werthmann.
For the Mormon fakes, see Naifeh.
- For analytical techniques, see Newman.
- For literature on stylistic analysis, see Konrad Oberhuber; Rendell.
- For information on the history of paper making, see Dard Hunter; John Krill.
- To recap: what one should know about a paper support in order to ascertain its quality or presence of inherent vice which is or may be a problem:
o the fiber direction - it influences curl, strain o whether the fibers are long or short -influences fold endurance, strength o whether the paper has been bleached -influences strength and color o whether the paper is acid -migrates to other items; discolors o whether it has many impurities -sensitive to humidity & light o whether it is coated or not -makes it sensitive to moisture
- For information on the history of media, see the following footnotes.
- Eastlake, C.L., Methods and Materials of Painting of the Great Schools and Masters, Vol. 1, Dover Publications, Inc. New York, 1960, p. 151.
- Wehlte, K., Materials and Techniques of Painting, Van Nostrand Reinhold Co., New York, 1982; Erhardt, D., W. Hopwood, M. Baker, and D. von Endt, "A systematic
