The Status of Research into the Authenticity of the Shroud

NICCOLO CALDARARO
Department of Anthropology
San Francisco State University

 In the article published by Doyle, et al.1: «The application of computer image processing technology to artifact analysis as applied to the Shroud of Turin study», one is left quite curious by the lack of comparative data, and of any convincing argument on the benefits of the methodology described. This problem is consistently found in most articles and studies on the Shroud. If we compare the Doyle. et al. study with the general literature on the Shroud and with the scientific literature on artifact analysis and that on the conservation of art and artifacts, identification of the Shroud as a unique object becomes questionable. Essentially Doyle and his co-workers have presented a rather comprehensive review of the use of the technology, but little scientific evidence that would either support their conclusions that the Shroud image was not painted (p. 5) nor that the application of this methodology has any real benefit for artifact analysis. Of particular concern is the fact that nowhere in their report are we told what the nature or origin of the image is that they are analyzing. Is it the Shroud, a photograph, or an image derived from a microdensitometer calibration translated to pixels from a photograph as in Lorrie & Lynn56, which seems reasonable to assume from the scan data on Doyle, et al.1? In which case how was the photograph made, under what conditions and with what camera, film, settings, lighting, etc.? This lack of basic detail makes assessment of their results difficult and the reproduction of their experimental procedure impossible.

The authors supply neither test results comparing the technique they introduce with other established methods - especially with regard to detecting brushstrokes (e.g., Albert G. Richard's 1956 article describing the use of radiographs of the topography of oil paintings2) or similar problems which called for the elimination of extraneous images which interfered with desired information in the image produced by radiography. In this case, reference may be made to Bridgman, Keck & Sherwood3 in the comparison of conventional radiography and electron emission radiography. The authors1 inability to discern brushstrokes is inconclusive as well, especially in reference to Hours4 failure in this regard in examining Leonardo's paintings using X-ray analysis. The comparative method is well established in the field of conservation when introducing new techniques of examination or evaluating their relative significance (e.g., Bridgman & Gibson5; Sayre & Lechtman6; Taylor, et al.7; Delbourgo8; Kushel9). The data that is presented concerning known classes of information are incomplete or unchallenging: for example, on page 41 the authors claim that the technique they performed on the Shroud gave «excellent indications of soilage type, blood staining as opposed to other body fluids, extent of scorching from a fire...» No effort is made by the authors to identify what «soilage type» (blood) they are referring to (whole blood? serum? human?) or what «other body fluids» they are comparing (urine? sweat?). No comparative methods or reference to other studies (compare Heller10, p. 120-192, with Fischer11, p. 127-133) was made and so little can be inferred from their presentation except that from their technique in the use of the hardware described and their particular approach to the Shroud as an artifact.

One is also at a loss to understand why the authors1 didn't compare their Shroud analysis with other images on textiles of the same and different fibre content and preparation; with images made from known media and methods (e.g., rubbings, paintings, experimentally aged human body fluid stains on linen etc.) and especially the transparent paintings of the 14th to 16th centuries12. These paintings, it must be noted, were often outlined with red pigments (the iron oxide seen by McCrone?17) and such underdrawings would not show up on IR13. The literature on the Shroud contains considerable information which could significantly affect their analysis: for example, it appears the Shroud was washed at least once in its history14; how would this affect their interpretation of their data on the image and their conclusions that it could not have been painted? Comparison of the Shroud with known copies executed in the period after the appearance of the Shroud in Lirey15, 16 would be of interest both for determining aging characteristics of the images as well as deterioration products of the linen/pigment/medium complexes. Also, by experiments to show whether or not the image was reduced by washing. McCrone17 has provided a telling argument identifying the image as a painting (but with the pigment applied without a brush).

Knowledge of the chemistry of the image is well established18-20. Pellicori21 & Gilbert & Gilbert's22 experiments with artificial aging different media on linen produced reflectance and fluorescence spectra similar to that of the Shroud image. However, Schwalbe & Rogers18, p. 23-24, argue that there is no evidence of a scorched medium which they believe would result from the 1532 fire. The image of the Shroud, therefore, appears to derive either from degradation products of the original painting's media in reaction with the cellulose of the linen support and an applied artist's pigment16, or in contradiction to Schwalbe & Rogers18, p. 23-24, the yellowing of the paint medium23-26. While McCrone finds iron oxide and vermilion by light microscopy, scanning electron microscopy (SEM), energy dispersive x-ray analysis (EDXRA), electron microprobe analyzer (EMA) and both x-ray (XRD) and electron diffraction (SAED) and no blood25, Heller & Adler27 and Heller10 report blood by Biuret-Lowry, fluorescamine, enzyme and albumin tests, anti-sera, hydrazine, Soret band absorption. The radiographic studies performed by the STURP team51, 52, were subject to instrumental and environmental bias and were inconclusive (by the authors' admission) as well as being conducted without reference to the extensive literature on the radiography of artifacts in general53 and painting in specific54. Fischer28 criticizes the latter authors'25-10 methods and advocates other forensic testing, while other scientists (e.g., Frache, Curto and Brandone14, 15) have used the same methods reported by Heller and Adler27 and Heller10 and found no blood but pigment instead. Ignoring for the moment the complexities of these apparent contradictory results it might be constructive to have the sticky tapes (taken by the STURP team from the surface of the Shroud) from the «blood» areas examined by Thomas Loy of the British Columbia Provincial Museum who has developed a method of detecting prehistoric blood residues on lithic tool surfaces dating 1,000 to 6.000 B.C.29. If the tapes contain blood, Loy should be able to detect and compare hemoglobin crystals to species of origin30.

While certain manipulation of an image is possible with computer-video system analysis, one must keep in mind that a video image (what the computer must work with) is not the image; it is not a photographic representation but a mechanized translation of the image by electro-mechanical transfer to pixel digitization. Just as with the Zapruder film of Kennedy's assassination or the JPL enhanced images by DiPietro & Molenaar31 of zoomorphic or anthropomorphic representations on Mars, interpretation of computer enhanced images is a rather imprecise science64; to purport that what the computer can add to, take away, or leave out of the video image it receives is more information is somewhat difficult to defend. It is unfortunate that Doyle. et al.1 did not refer to the earlier and more thorough use of image processing and radiography applied to the analysis of art reported in the text edited by Price55. Mueller32,, p. 88-90, has already questioned the data manipulation employed by Jackson, Jumper & Ercoline which produced the 3-D images of the Shroud. The limited data set from which the programs and procedures for the VP-8 images were developed are a poor foundation for general conclusions57. The failure of the VP-8 computer to «correlate relief over large scale distances»57 seriously undermines the claims made for the existence of a «global mapping function» for the Shroud. What is more the force of their study is seriously diminished by limiting their sample of comparative images to modern drawings on paper. They could have strengthened their study by using Medieval paintings on canvas so that both technique and aging characteristics could be assessed. The use of a painting by Fetti is not sufficient for a proper analytical series. As Druzik, et al.34 state: «Digital image processing does not create information which is not contained in the original images in some form», but whether 'enhancement' by computer programming can clarify what we do see is what is promising in this new method and others like it which can compare and contrast information from various optical sources with related data whether they be chemical or physical. In the same article mentioned above by Druzik, et al.34, the subject analyzed is a work on paper fixed to an oak panel on which is painted another image. Computer enhancement removed the wood striations in the panel as well as what was assumed to be the overpainted image. What results is not a clearer image; rather the enhancement actually achieves a darker image by the removal of pixels. The remaining image is essentially the same as the underlying image seen in the initial radiograph but it is a matter of opinion that it is clearer or represents «new information» contained in that image. What we must be sure to avoid are 'artifacts' produced by the program used to analyze an image; is the «monkey on Mars» which the JPL computers «enhanced» through DiPietro & Molenaar's programs of video data from NASA space missions, really in our mind's eve and not actually monumental ruins on the planet31?

In general, the authors' treatment of the Shroud as an artifact is unscientific. To analyze an artifact with reference to authenticity one must compare it to other materials of known provenance which the authors fail to do. While we may be skeptical about the nature of the image and its survival in its present form, one must question the state of preservation of the Shroud cloth. In approaching artifacts one is often put off by the artifact which appears to be too real, to possess an appearance and attributes which are too much expected: and also one must keep in mind that artifacts are often produced by forgers with the attributes of what contemporary sources expect the artifact to possess35, 36. Still, an artifact that appears too good, i.e., in a preserved condition that we do not expect, also attracts a negative bias, for example, the scrolls of the Shapira Affair37. This caution does not add support for the Shroud, however, as any artifact must be considered in the context of like artifacts representing a series of examples in time and state of presenation38. Taken in the context of such a series, containing the basis of analysis and comparison given by the states of preservation and the identified (if possible) agencies of deterioration, judgements may then be made on a more reasonable basis.

Such a series of objects exists and examples can be drawn from numerous sources: ranging from images on cloth (e.g., Veil of Veronica14, p. 46) to clothing supposedly belonging to Christ (e.g., the Holy Coat of Trier, with a provenance to the 4th Century A. D.), to linen in various states of preservation from the recent past to the Middle Ages (the Holy Cap of Cahors39), the Roman period and Egyptian samples to 2.000 B.C. (e.g. a linen with a herrinbone pattern similar to the Turin Shroud described by Needler40, p. 238-251; the burial clothes of the Gayet Collection in the Louvre Palace Museum, see Tribbe41, and those from the Greco-Roman Period in the Victorian & Albert Museum, see Kendrick42). Testing the cellulose deterioration of a varied group of these linen artifacts and comparing them with the Turin Shroud would greatly add to our knowledge of the Shroud as artifact. In this regard a comparison of pollen analysis between several of these objects (and especially the Turin Shroud and the Shroud of Cadouin which is assumed to have had a similar history of travel though now known to be of eleventh century Moslem origin, see Wilson43, p.76, would be most enlightening.

Finally, reference might also be made to the Coptic practice of painting on shrouds (Renner44). It might be interesting to explore the possibility of a Coptic shroud painting being either the inspiration for the Turin Shroud, or once washed free of its original painting, forming the foundation of it. A cloth covering a shroud painting (or other painting or painted surface) could result in an image transfer which we often see in conservation. In prints and drawings which have been framed in the same materials for approximately 20 years or more we often see an image transfer to the glass covering the art work58. This image is usually a negative according to Weidner58, and my own experience of more than 20 years in the field, however, Ellis59 reports some positive images as well. Although they are often difficult to interpret, as the images on the glazing are usually ghost-like and vary in intensity to the extent that reverse images can be misinterpreted as reverse ones and vice versa. What we are describing, then, is a combination of a vapor image theory and a contact theory66.

Although these images may result from acid migration and microenvironments created from the interaction of the deterioration products of lignin from framing materials, inks, etc., other similar images are produced by the action of fungus on the paper support of art work in contact with glazing materials58. Ellis59 separates these processes into several distinct events which we observe in framed works of art.

V. Daniels63 describes some of the chemical processes involved in these images in detail, identifying peroxides as the primary agent. The mechanism which creates these negative images (and some positive ones as well) might also explain the «dorsal» image of the Turin Shroud which has been found not to contain the same degree of 3-dimensional features in its shading33, 18. The Turin Shroud might have been draped over any painted surface (e.g., a polychrome sculpture) and the dorsal image been a residual image created from the same process that created the frontal one.

This is, admittedly, no less a speculation than other conjectures on the Shroud's image formation, since while we have abundant examples of such images on glazing and cellulosic supports from framed prints we do not have such examples from polychrome sculptures. However, we could speculate that a cover was used for the transfer of a sculpture, perhaps like the supposed statue by Nicodemus that the Byzantine emperor Nicephorus brought to Constantinople65. This would explain the size of the Turin Shroud which is wrong when compared to New Testament descriptions of the cloth used in Christ's burial as well as those required for traditional Jewish burial of the time14, 15, 49. Such a cover could also explain the added piece sewn on one side of the Turin Shroud as a measure to make it drape over the entire object. It would be interesting to note if there is any evidence of the sides being sewn together at any time in the past.

Riggi's identification of «a substance chemically resembling natron»46 would support the possibility of image formation on a cloth derived from a burial shroud (painted or not) or a cloth in long contact with a shroud, natron being a chemical traditionally used in ancient Egypt to dehydrate a corpse prior to embalming50, though it appears mummification became less common among the Christianized Egyptian population after the 4th Century A. D.

This relationship between natron and the Turin Shroud could be further studied by chemical tests of Coptic shrouds in the Vatican Collection or the large collection of Coptic textiles in the Municipal Museum at the Simeon Convent in Trier47. One must note the similarity in elongated fingers in the Coptic shroud illustrated by Renner44, that illustrated by Kybalova60 and the fingers of the man of the shroud. Also, the detail of the same Coptic shroud in Renner's book shows a hand without a thumb similar to the «missing thumb» of the Turin Shroud which has been used as evidence of crucifixtion42-48. This «missing thumb» may simply be a stylistic motif of Coptic painting. While the shroud painting illustrated by Kybalova also shows a palm view of a hand with a thumb as well as elongated fingers on both hands, the figure's other hand is shown from the side without a thumb. (This could be true of the opened palm hand barely visible in the deteriorated area in the illustration in Renner, also.) Since the figure is depicted holding a glass, the thumb may be «missing» due to the artist's belief that the thumb should be out of view at the painting's perspective. It is certain, however, that the thumbs are missing in 3rd Century mummary portraits illustrated by Thompsen61 from the early 3rd to late 4th Centuries in Egypt's Fayum. He does illustrate one example with thumbs on both hands from the late 4th Century. Cooney62 illustrates some 4th to 7th Century Coptic portraits all displaying thumbs. We might therefore theorize that this «missing thumb» feature is a stylistic element present either as an early phase or a regional variant.

The possibility remains of the Turin Shroud resulting from the contact of a draped cloth over a human body, whether alive or dead. It seems rather unlikely, however, since we have no such examples of images on cloth formed in this way while, on the other hand, we have continuous and long experience with negative images formed by transfer from works of art. The negative image nature of the Turin Shroud is held as one of its unique and unexplainable characteristics48, but as we have shown, such images are neither unique nor rare nor unexplainable. However, since it is known that the Gnostics did have sculptural representations of Christ in addition to images of Christ in paintings65, we thus have the historical object to impart an image, the stylistic «missing thumb», an image-forming process and an image (the Shroud of Turin). Is this a sufficient chain of causality? Not in terms of our criteria. We need examples of images formed by contact with sculpture (or of some other format for paintings) that could account for the double image of the Turin Shroud in order to establish a historical series. «One of a kinds» must always remain suspect. Such an image transfer, nevertheless, especially as Ellis describes it, could account for both the pigment found by McCrone17, as well as the experimental images produced by Pellicori21.

If the Shroud of Turin is an artifact, it must be treated as any other archaeological or ethnographic object. It must be analyzed in the context of other similar objects. Without context and provenance, any object purported to be archaeological is suspect. The Shroud of Turin's provenance, as drawn by Wilson rests on a rather unlikely foundation: its being the Mandylion43. If this were so then the Shroud would exhibit, in the reported exposed circular area of the Mandylion coverlet43, a greater deterioration produced by photooxidation. This is disproved by the various tests performed by the STURP team18-21-22. We would also expect to see considerable damage caused by hydrolysis in the areas of the Mandylion which are documented to have been regularly wiped with fluids49.

I would like also to say something about the effect of deterioration products of various organic substances, including paint media and wood resins, which can produce similar images, such as the shroud67. The interaction of peroxides and hydroperoxides on cellulosic materials can produce the type of discoloration seen on shroud fibers68. The Conservation Analytical Laboratory (CAL) of the Smithsonian Institution has investigated the complexity of the transfer of images onto adjacent materials (Padfield, Erhardt & Hopwood, ms.). In images formed in frames by transfer from pictures of various kinds, one often notes on the glazing that a substance has formed on the surface of the glazing. This substance can be rubbed off with a finger. Padfield and others at the CAL analyzed one example of such an image transfer and found the substance to be mainly sodium chloride and an organic material with surfactant properties. The salt was present from the picture's salted silk. A liquid, mobile phase of deliquescence was apparently the main agent of transfer, aided by the surfactant. Relative humidity and even weave structure were transfer factors. As I have already noted, textile fibers and finished textiles are often treated prior to manufacture to prepare the fibers for weaving or use. Chemical interactions of agents used in such treatment can be active in image transfer and image formation. The CAL study involves only one type of image transfer in picture frames. Several very different types exist, for example, image transfer to back mats in matted works of art and photographic latent image transfer of un-neutralized reagents.

The Turin Shroud certainly deserves further study but in the form of scientific comparative analysis and context.

NOTES

1 Doyle, Lauance R., Lorre, Jean J. & Doyle, Eric B.: The application of computer image processing techniques to artifact analysis as applied to the Shroud of Turin study. In: Studies in Conservation, vol. 31, 1, February 1986, p. 1-6.

2 Richards, Albert G.: Method for radiographing the topography of oil paintings. In: Studies in Conservation, vol. 2, 4, October 1956, p. 189-191.

3 Bridgman, C.F., Keck, S. & Sherwood, H.F.: The radiography of panel paintings by electron emission. In: Studies in Conservation, vol. 3, 4, October 1958, p. 175-182.

4 Hours, Madeline: Secrets of the Great Masters, G.P. Putman, New York 1964.

5 Bridgman, Charles F. & Gibson, H. Lou: Infrared luminescence in the photographic examination of paintings and other art objects. In: Studies in Conservation, vol. 8, 3, 1963, p. 77-83.

6 Sayre, Edward V. & Letchman, Heather N: Neutron activation autoradiography of oil paintings. In: Studies in Conservation, vol. 13, 4, November 1968, p 161-185.

7 Taylor, Kalhleen K.; Cotler, Maurice J. & Sayre, Edward V.: Neutron activation autoradiography as a technique for conservation examination of paintings. In: Bulletin, AIC, vol. 15, 2, Summer 1975, p. 93-102.

8 Delbourgo, Suzy: Application of the electron microprobe to the study of some Italian paintings of the Fourteenth to the Sixteenth Century. In: Norman Brommelle & Perry Smith ed.: Conservation and Restoration of Pictorial Art, Butterworths, London 1976, p. 27-35.

9 Kushel, Dan A.: Applications of transmitted infrared radiation to the examination of artifacts. In: Studies in Conservation, vol. 30, 1, February 1985, p. 1-10.

10 Heller, John H.: Report on the Shroud of Turin, Houghlon Mifflin, Boston 1983.

11 Fisher, John: Is the 'blood' blood? In Nickell, Joe: Inquest on the Shroud of Turin, Prometheus, Buffalo 1983, p 127-132, 149-152.

12 Eastlake, Sir Charles Locke: Methods and Materials of Painting of the Greal Schools and Masters, vol 1, 1847, p. 91-112, reprinted by Dover, New York 1960.

13 Real, William A.: Infrared reflectography at the Cleveland Museum of Art: Paintings, Objects, Manuscripts. In: AIC Preprints, Washington D.C., May 1985, p 79-89; Van Asperen De Boer, J.R.J.: Reflectography of paintings using an infra-red vidicon television system. In: Studies in Conservation, vol. 11, 3, August 1969, p. 96-118; Wolters, Christian: A Tuscan Madonna of c. 1260: Technique and Conservation. In: Studies in Conservation, vol. 2, 2, October 1955, p. 87-96.

14 Sox, H. David: File on the Shroud, Hodder & Stoughton, London 1978.

15 Sox, H. David: The Image of the Shroud: Is the Turin Shroud a forgery?, Unwin, London 1981.

16 Nickell, Joe: Inquest on the Shroud of Turin, Prometheus Books Buffalo 1983. For other extant images of Christ on cloth, see Green, Maurus: Enshrouded in Silence. In: Ampleforth Journal, vol. 74, Autumn 1969, Part III, p. 319-345.

17 McCrone, Walter C.: Microscopic study of the Turin 'Shroud', IV. In: Bulletin of the American Institute for Conservation, Chicago, May 1986, p. 77-96.

18 Schwalbe, L.A. & Rogers, R.N.: Physics and chemistry of the Shroud of Turin: a summary of the 1978 investigation. In: Analytica Chimica Acta, vol. 135, 1982. p.3-49; Jumper, Eric J.; Adler, Alan D.; Jackson, John P.; Pellicori, Samuel F.; Heller, John H. & Druzik, James R.: A comprehensive examination of the various stains and images on the Shroud of Turin. In: Archaeological Chemistry III, Adv. in Chem. Ser. 205, American Chemical Society, 1984, p. 447-476.

19 Mueller, Marvin M.: Comment on Meacham: Authentication of Turin Shroud. In: Current Anthropology, vol. 24, 3, June 1983, p. 299.

20 Schafersman, Steven: Comment on Meachan: Authentication of Turin Shroud. In: Current Anthropology, vol. 24, 3, June 1983, p.301-302.

21 Pellicori, S. F.: Spectral properties of the Shroud of Turin. In: Applied 71. Optics, vol. 19, 12, 15, June 1980, p. 1913-1920; Pellicori, S. F. & Evans, M. S.: The Shroud of Turin through the microscope. In: Archaeology, 34, 1981, p. 34-43.

22 Gilben, Roger, jr. & Gilbert, Marion M.: Ultraviolet-visible reflectance and fluorescence spectra of the Shroud of Turin. In: Applied Optics, vol. 19, 12, 15, June 1980, p. 1930-1936.

23 McCrone, Walter C. & Skirius, C.: Light microscopical study of the Turin 'Shroud', I. In: Microscope, vol. 28, 1980, p. 105-113.

24 McCrone, Walter C.: Light microscopical study of the Turin 'Shroud', II. In: Microscope, vol. 28, 1980, p. 115-128.

25 McCrone, Walter C.: Microscopical study of the Turin 'Shroud', III. In: Microscope, vol. 29, 1981, p. 19-38.

26 McCrone, Walter C.: Personal Communication, 1987.

27 Heller, John H. & Adler, Alan D.: Blood on the Shroud of Turin. In: Applied Optics, vol. 19, 16, 14, August 1980, p. 2742-2744.

28 Fischer, John F.: Letter to the Editor. In: Microscope, vol. 29, 1981, p. 69-70.

29 Loy, Thomas H.: Prehistoric blood residues: detection on tool surfaces and identification of species of origin. In: Science, vol. 220, 17, June 1983, p. 1269-1271.

30 Nelson D. E.; Loy, T. H.: Vogel J. S. & Southom, J. R.: Radiocarbon dating blood residues on prehistoric stone tools. In: Radiocarbon, vol. 28, 1, 1986, p. 170-171. According to Loy (Personal Communication, 1987). «Isoelectric Focussing, and immunological detection techniques directed toward the identification of immunoglobins now augment and largely supplant the earlier reliance upon detection of hemoglobin (heme unit, which unforunately for these studies can be confused with the heme-like structure of chlorophyll) and crystalization for identification of blood residues and species of origin of those blood residues.» (See Bahn, in: Nature, vol. 330, 5, November, p. 14).

31 Di Pietro, Vincent & Molenaar, Gregory: Unusual Mars Surface Features, 3rd. ed., Glen Dale 1982.

32 Mueller, Marvin M.: Resurrection Radiance? Chapter 8, in: Joe Nickell, Inquest on the Shroud of Turin, Prometheus Books, Buffalo 1983, p. 85-94.

33 Jackson, J.P.: Jumper, E.J. & Ercoline, W.R.: Three-dimensional characteristics of the Shroud Image. In: Proceedings of 1982 IEEE Int. Conference of Cybernetics and Society, p. 559-575.

34 Druzik, James R; Glackin, David L.; Lynn, Donald L. & Quiros, Raim: The use of digital image processing to clarify the radiography of underpainting. In: JAIC, 22 1, Fall 1982, p. 49-56. A similar effect is seen in the «piecewise linearization» images produced by John D. German, Jr.: An electronic technique for constructing accurate three-dimensional Shroud image. In: Kenneth E. Stevenson, ed: United States Conference on the Shroud of Turin. In: STRUP, Albuquerque 1977, p. 234-240.

35 Hulmer, Eric C.: The Role of Conservation in Connoisseurship, Dissertation, University of Pittsburgh 1955 (available from University Microfilms International, Ann Arbor, Michigan).

36 Kurz, Otto: Fakes, Faber & Faber, New York 1948 (revised edition Dover Publications, New York 1967).

37 Allegro, John Marco: The Shapira Affair, Doubleday, Garden City 1965.

38 Kahle, T. B. & Caldararo, Niccolo: State of preservation of the Dead Sea Scrolls. In: Nature, vol. 321, No. 6066, 8, May 1986, p. 121-122.

39 Montaigne, Abbe: Notice Historique sue la Sainte-Coiffe; ou: Dissertation sur le Saint Suaire Conservé dans l'eglise Cathedrale de Cahors, G. Richard, 1844.

40 Needler, Winifred: Three pieces of unpatterned linen from ancient Egypt in the Royal Ontario Museum. In: Veronika Gervers ed.: Studies in Textile History, Royal Ontario Museum, Toronto, Canada, 1977, p. 238-251.

41 Tribbe, Frank C.: Portrait of Jesus?, Stein & Day, New York 1983.

42 Kendrick, A. F.: Catalogue of Textiles from Burying-grounds in Egypt, vol. 1, Victoria & Albert Museum, London 1920.

43 Wilson, Ian: The Shroud of Turin: The Burial Cloth of Jesus Christ?, Doubleday, New York 1978.

44 Renner, Dorothee: Die koptischen Textilien in den Vatikanischen Museen, Franz Steiner Verlag, Wiesbaden 1982.

45 Humber, Thomas: The Sacred Shroud, Pocket Books, New York 1974.

46 Riggi, Giovanni: Electronic scanning microscopy and microanalysis of dust taken from burial fabrics of Egyptian mummies in relation to dust taken from the Shroud of Turin. Paper read at the STRUP conference, New London, Conn., October 9, 1981. Cited by William Meacham: The authentication of the Turin Shroud: An issue in archaeological epistemology. In: Current Anthropology, vol. 24, 3, June 1983, p. 283-311.

47 Ahrens, Dieter: Schafe oder Kamele? In: Textilforum 4, December 1985, p. 57.

48 Meacham, William: The authentication of the Turin Shroud: An issue in archaeological epistemology. In: Current Anthropology, vol. 24, 3, June 1983, p. 283-311.

49 Drews, Robert: In Search of the Shroud of Turin, Rowman & Allenheld, Totowa 1984.

50 Lucas, A.; Antiques: Their Restoration and Preservation, Edward Arnold & Co., London 1924 (1932 revised ed.), p.231-232.

51 Morris, R. A.; Schwalbe, L. A. & London, J. R.: X-Ray Fluorescence Investigation of the Shroud of Turin. In: X-Ray Spectrometry, vol. 9, 2, 1980, p.42-47.

52 Mottern, R.W.; London, R.J. & Morris, R.A.: Radiographic Examination of the Shroud of Turin - a Preliminary Report. In: Materials Evaluation, December 1980, p.39-44.

53 Gilardoni, Arturo; Ascani Orsini, Riccardo & Taccani, Silvia: X-Rays in Art - Physics - Technique - Application, Mandello Lario, Como, 1977; Young, Wllliam J., ed.: Application of Science in Examination of Works of Art, Research Laboratory, Museum of Fine Arts, Boston 1965 & 1973.

54 Hours, Madelaine & Faillant, Lola: Etude Radiographique, Laboratoire de Recherche des Musees de France, 1975.

55 Everette, Jr.; James. A.: Gibbs, Julian S.; Diggs, Joseph; Brumbaugh, Thomas; Sloan, Malcolm; Grogan, Kevin; Price, Ronald R. & Erickson, Jon J.: The use of digital radiographic techniques in the analysis of works of art with an emphasis upon painting. In: Book, Digital Radiography: A Focus on Clinical Utility; edited by Ronald R. Price; F. David Rollo; W. Gordon Monahan & A. Everette James, Groune & Stratton, New York 1982, p. 335-343.

56 Lorre, J.J & Lynn, D.J.: Digital enhancement of images of the Shroud of Turin. In: Kenneth E. Stevenson (ed.), Proceedings of the 1977 U.S. Conference on the Shroud of Turin, Holy Shroud Guild, New York 1977, p. 154-181.

57 Jackson, John P; Jumper, Eric J. & Ercoline, Wlliam R.: Correlation of image intensity on the Turin Shroud with the 3-D structure of a human body shape. In: Applied Optics, vol. 23, 14, 15, July 1984, p. 2244-2270. (See also Jumper, E. J.: An overview of the testing performed by the Shroud of Turin Research Project with a summary of results, IEEE, 1982. In: Cybernetics and Society Int. Conf. Proc., p. 535-537; Schwortz, Barrie M.: Mapping of research test-point areas on the Shroud of Turin. In: ibid., p. 538-547; Devan, D. I. & Miller, V.D.: Quantitative photography of the Shroud of Turin. In: ibid., p. 554-558; Jackson, J., et al.: Three-dimensional characteristic of the Shroud of Turin. In: ibid., p. 559-575; Ercoline, W., et al.: Examination of the Turin Shroud for image distortions. In: ibid., p. 576-579).

58 Weidner, Marilyn Kemp.: Damage and deterioration of art on paper due to ignorance and the use of faulty materials. In: Studies in Conservation, vol. 12, 1, February 1987, p. 5-25.

59 Ellis, Margaret Holben: The Care of Prints and Drawings, AASLH Press, Nashville 1987.

60 Kybalova, Ludmila: Les tissus Coptes, Editions Cercle D'Art, Paris 1967.

61 Thompson, David L.: Mummy Portraits in the J. Paul Getty Museum, The J. Paul Getty Museum, Malibu 1982.

62 Cooney, John D.: Late Egyptian and Coptic Art, Brooklyn Museum, 1941. See also the 1943 edition, figure 3.

63 Daniels, V.: The Russel Effect - a review of its possible uses in conservation and the scientific examination of materials. In: Studies in Conservation, vol. 29, 2, May 1984, p. 57-62.

64 DiPietro (Personal Communication, 1988) and his associates have developed a new program for image enhancement which may reduce some of the program «artifacts» produced by other systems, see DiPietro, Vincent & Molenaar, Gregory: Unusual Mars Surface Features, 5th edition.

65 Smith, Sir Wllliam & Cheetham, Samuel: A Dictionary of Christian Antiquities, vol. 1, John Murray, London 1893, p. 874.

66 Stains are also known to result from the interaction of sap in wood and fungi (see Lilja, J.: Fungi causing airborne sap stain in wood and efficacy of some fungicides against them, Folia Forestalia, Institutum Forestale Fenniae, 592, Finland 1984). We ako know that with stains on paper those stains caused by water, «... are a complex phenomenon and are often most intensely colored at the water/air/paper interface», from Vincent Daniels: The discoloration of paper: origins and treatment, Abstract from Conference notes of the Institute of Paper Conservation, Oxford 1986, p. D123. Daniels (Personal Communication, 1988) agrees that such a transfer is possible specifically that, «a drying oil will release large quantities of eventually brown materials migrating by the liquid phase and evolves large amounts of volatile low molecular weight compounds which would cause yellowing to give the required negative image».

67 Gove, H. E.: Dating the Turin shroud - An assessment. In: Radiocarbon, 32, 1, 1990, p. 87-92.

68 Daniels, V.: The discoloration of paper on ageing. In: The Paper Conservator, 12, 1988, p. 93-100.