The question of which came first, the blood or the image, is an important factor in the assessment of whether the Shroud is medieval or ancient, and a new paper by Kelly Kearse is the first to explore some aspects of it in any depth since John Heller and Alan Adler wrote about it in ‘A Chemical Investigation Of The Shroud Of Turin.’1 They wrote that the fibres of the Shroud cloth looked “corroded” under phase contrast microscopy, from “slightly” to “very” as the colour changed from “pale yellow” to “yellow” to “dark.” They classed these fibres as “non-image,” “body-image,” and “scorch” respectively. Some 300-year old Spanish linen behaved similarly when heated, from “similar to Shroud pale yellow fibrils” before heating, to “more corroded” after an hour at 100°C, and “similar to Shroud scorch fibrils” after half an hour at 250°C.
They further noted than when “red coated” and “golden-yellow” fibres were treated with a cocktail of proteolytic enzymes, not only did the red particulates and golden-yellow coating completely dissolve away, but in both cases, the underlying fibres then “closely resemble the non-image fibrils when viewed under phase contrast.” The protease had no effect on the image or the non-image fibres.
There is no specific mention of the removal of the ‘corrosion’ by the protease, nor any specific suggestion that there is no “image” on the “blood” fibres in this paper, but it is a valid, if inconclusive, inference. The official Summary of the 1978 investigation says: “the ‘blood’-stain composition poses an interesting problem in itself, and the observations may ultimately give some clues to help us understand how the image was formed. For example, one important question that might be answered is whether the ‘blood’ or the image was applied first.”2
That the question remained unresolved is demonstrated in the postulated 1984 schedule of investigations, in which one of the questions they hoped to answer was: “In what temporal order did the blood and body images physically appear on the Shroud?”3 In 1986, Eugenia Nitowski, who with her colleague Joseph Kohlbeck examined and photographed many of fibres on the sticky tape slides herself, reported: “Corrosion on fiber surfaces. Alan Adler photographed the surface of Shroud image fibers and noted that they appeared corroded. This was not reported, to my knowledge, by anyone else, however, on my own Jerusalem Test Cloth 4, I found image fibers to be corroded, but I never observed this on Shroud fibers.”4
As far as I know, none of Alan Adler’s photographs have been published, but some idea of what can be found on the tapes can be seen in microphotographs taken by Walter McCrone and Eugenia Nitowski. Unfortunately, they are very inconsistent regarding the conditions under which they were photographed, in terms of magnification, lighting, and filtration, so no easy comparison can be made between them.
What exactly motivated the decision behind the selection of sites for the sticky tape samples is unclear, but it is remarkable how few ‘pure’ samples of non-image, image, and blood sites were taken. It is also remarkable how similar the adventitious debris collected appears on each slide, regardless of where it came from. Heller and Adler divided the fibres into seven categories, “very pale,” “pale yellow,” “yellow” and “dark,” followed by “red coated,” “golden-yellow coated” and “birefringent red particulate coated,” and hoped that these corresponded to “backing cloth and patch,” “non-image,” “body image,” “scorch,” “blood,” “margins of blood,” and “waterstain margins and blood scorch areas.” Much of this was inevitably subjective, as it wasn’t then, and still isn’t, possible to divide the spectrum of different colours precisely into these seven classes, to know exactly where each sticky tape was applied, or to know where any particular fibre on any tape originally came from. They suggested that finding 15 fibres of any selected type would be their criterion for establishing what sort of area it came from, but as each tape contained hundreds of fibres, finding 15 of any type on every one was not difficult.
Walter McCrone carried out two blind determinations of tape content, firstly assigning each tape to “image” or “non-image” according to the amount of particles he saw, and correctly identifying 28 out of 32, and secondly asking one of his students to divide all the fibres on 12 tapes, about 10,000 fibres, into “coloured” or “uncoloured,” and calculating the proportion of coloured to uncoloured. These amounted to 10% on a slide from the Holland cloth to 72% on one from a finger, although to my mind the results are not as conclusive as McCrone hoped. The finger is certainly among the darker parts of the image, but the deeply ‘blood’-stained wrist, chest and heel wounds contained only 37% – 46% ‘coloured’ fibres.5
Perhaps the best way to look at the Shroud fibres is not using the microphotographs at all, but instead to examine Mark Evans’s close-ups of the Shroud itself. These show the fibres in context, and without the selection process that comes with the application of sticky tape, looking at tiny areas of the tape under a microscope, selective removal of the fibres from the tape and cleaning them with toluene. Here is a series of three nested photos from the dense blood area in the small of the back (from Shroud Scope):
The head is to the left, and there is another strand of the blood belt immediately to the right of the photo. The larger of the two close-ups bears closer inspection:
It is clearly rather simplistic to talk of a “red-coated” fibre. The blood is represented as clumps or flakes, and does not “coat” any of the fibres.
There is also uncertainty about the protein content. Concerned as to whether the image had a protein component, Heller and Adler tested image fibres with Amido Black, which returned a positive result. However, they found that Amido Black would stain pure linen as well, so that it was not possible, using this test, to say whether there was protein present or not. Walter McCrone also tested for protein using Amido Black, which returned a similar positive result; however, he wrote; “It is true that cellulose itself stains with Amido Black but when the fiber is washed with the drop of dilute acetic acid, the blue is removed from the cellulose but not from any proteinaceous substance.” He published some photographs of his tests in ‘Judgment Day for the Turin Shroud,’ but as they were all described as “blood image,” it is not clear that the image alone tested positive, or was even tested at all. Heller and Adler went on to use further tests, such as fluorescamine, and said, “The fluorescamine tests were definitely negative on all fibrils away from blood areas.”
And about the starch content. Heller and Adler reported that “the uncoated fibrils, body image. non-image and scorch fibrils” were all tested for starch, with negative results. On the other hand they also suggested that “It should be noted that although all of the other organic tests are negative, this does not preclude the possibility that some of these substances may have resided on the cloth in the past and been ‘lost’ over time through oxidation, degradation, etc. […] This would also apply to trace amounts of Saponaria.” The first statement is in direct contradiction to Raymond Rogers observation that “We expected to find starch on the Shroud, so we did not specifically look for it. That was an unfortunate oversight,”6 but the second more or less coheres with Rogers’s “We could find very little confirmatory evidence for the use of Saponaria on the Shroud. The age of the cloth and damage during the fire of 1532 make some chemical testing difficult. More work needs to be done. However several circumstantial bits of evidence that Saponaria might have been present early in the history of the cloth should be mentioned.”
Later Rogers wrote that “The presence of starch, in particular amylose, on the shroud was confirmed by the fact that during testing for sulfoproteins in blood areas with an iodine-azide reagent (which bubbles vigorously when sulfur is present), a reddish background was formed,”7 and that “The observed effects must have been caused by different amounts of impurities that originally coated the surfaces of the threads as a result of slightly different production conditions.” He specifically decided that “the cellulose was not involved in the color-producing chemistry of the image,” although following Heller and Adler he was convinced that “whatever process produced the image, colour must have occurred after the blood flowed onto (or was painted onto) the cloth, and the image-producing process did not destroy the blood.”8
I don’t find any of this convincing, and the more detail is added the less coherent it appears. I can’t, from the observations listed above, positively refute the possibility that the blood was applied before the image, but nobody could say that the opposite had been proved, including, as I have shown above, STuRP itself. My opinion is that the image was applied first, and the blood some time later, possibly years.
Kelly Kearse approaches the matter from a different angle. Suppose the image was indeed applied before the blood, but the blood somehow meant that the image disappeared. Then both sides could be correct. A) The image was applied before the blood, but B) there is no image under the blood. It would be a clever reconciliation of the two sides.
Firstly, he asks, what do we mean by image? Medievalists like myself suggest that it is primarily a discolouration of the primary cell walls of the flax using acid. Miraculists think it is a discolouration of the primary cell walls of the flax using electromagnetic or sub-atomic radiation. Another possibility proposed by Nicholas Allen, is that it is a discolouration of the primary cell walls of the flax from the effects of chemistry related to photography. Kearse prepared samples using all these methods, applied blood, removed it with protease, and photographed the results next to control samples where no blood was applied.
1). Cloth treated with acid, no apparent discolouration, covered with blood, then heated.
2). Cloth treated with acid, no apparent discolouration, heated, then covered with blood.
3). Cloth chemically treated, discolouration apparent, covered with blood, heating not necessary.
4). Cloth irradiated weakly with a laser, no apparent discolouration, covered with blood.
5). Cloth irradiated more strongly with a laser, discolouration apparent, covered with blood.
(for full details, see Kearse’s paper)
As can be seen, some of these treatments resulted in immediate colouration of the cloth, while others needed heat to make anything visible. The point of heating is to simulate “aging,” by which a latent image becomes visible. How visible the image on the Shroud was before heating/aging is a moot point. From an authenticist point of view, there is no specific reason why the Shroud should have had an image on it for years, and some people think that its invisibility at the time of discovery just after the Resurrection explains why no image is mentioned in the Gospels. From a medievalist point of view, it is most unlikely that its creator deliberately produced an invisible image. However, it is possible that, if it were done using visible pigment in an invisible medium, the original image was due to the pigment, and the image we see now is due to the medium ‘developing’ over time. It is also possible that the original painting was hot-ironed to remove wrinkles, and the heat from that ‘developed’ an otherwise latent medium effect.
Anyway, when all these experiments were treated with protease and the blood completely removed, only in cases (1) and (3) was the colour of the cloth returned to its pristine state. It seems that before the acid has sufficient heat/time to discolour the cloth, the buffering qualities of blood effectively neutralises it, but after it has had adequate heat/time for colour to appear, then it doesn’t. In other words the blood prevents the forming of a visible image, it does not remove any image already formed.
In the case of the photographic chemicals, the blood did appear to remove the colour, so that when the blood was removed, the cloth was lighter than it was after chemical treatment. This sample was not, as far as I can see, heated, which might have fixed the discolouration more permanently.
In the case of the laser treatment, both samples were unaltered by the blood, and looked the same after it was removed. Sample 4 remained uncoloured, sample 5 remained coloured. To confirm that sample 4 had been affected by the laser, it was found that before adding the blood it fluoresced under ultraviolet light, and that after adding and removing the blood, the latent colouration could nevertheless be rendered visible on heating.
Kearse’s paper concludes with a separate study, considering the possibility that even if the blood were applied first, the image making mechanism might do its job regardless, through the blood ‘shield.’ This was only tested using the laser treatment, and then only at the weaker ‘latent image producing’ level, as the stronger level affected the blood as well. Finally samples treated with blood and serum alone were treated to very low levels of laser radiation, when it was found that serum did not protect the cloth, but whole blood did.
In conclusion, Kearse begins by saying that it is clear that in some circumstances, blood applied after an acidic degenerant of cloth could negate its activity, giving the impression, after the blood was removed, that there was “no image under the blood,” but only if the acid had not discoloured the cloth before the blood was applied. Otherwise, blood could bleach existing discolouration only in the case of the photographic chemicals.
The conclusion is worth quoting in full:
“In summary, the current report has investigated various circumstances related to the sequential order of blood and image addition to the Shroud of Turin. These studies show that addition of blood to acid treated linen nullifies subsequent coloration, offering a potential example of no image underneath blood involving artistic creation. Additionally, the suggested “bleaching effect” of blood was addressed and shown to be restricted to only one out of three coloration systems that were examined [the photographic chemicals]. Hence, the general conclusion is that blood added after coloration is unable to reverse it. Lastly, these studies document that linen underneath blood (or serum) was affected by energy transfer from radiation, even [but only?] under conditions corresponding to latent coloration.”
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1). ‘The Sequential Addition of Blood and Image to the Shroud of Turin,’ Kelly Kearse, International Journal of Archaeology, 2026
– – ‘A Chemical Investigation of the Shroud of Turin,’ John Heller and Alan Adler, Canadian Society of Forensic Sciences Journal, 1981
2). ‘Physics and Chemistry of the Shroud of Turin, A Summary of the 1978 Investigation,’ Lawrence Schwalbe and Raymond Rogers, Analytica Chimica Acta, 1982
3). ‘Formal Proposal for Proposing Scientific Research on the Shroud of Turin,’ STuRP, 1984
4). ‘Criteria for Authentication: A Procedure for the Verification of Shroud Samples,’ Eugenia Nitowski (as Sister Damien of the Cross), 1986
5). Judgement Day for the Turin Shroud, Walter McCrone, 1997
6). ‘An Alternate Hypothesis for the Image Color,’ Raymond Rogers (at shroud.com)
7). ‘The Shroud of Turin: An Amino-Carbonyl Reaction (Maillard Reaction) may Explain the Image Formation,’ Raymond Rogers, Melanoidins in Food and Health Volume 4, Jennifer Ames (ed.), 2003
8). ‘Scientific Method Applied to the Shroud of Turin: A Review,’ Raymond Rogers and Anna Arnoldi, 2002 (at shroud.com)