Claims of Invalid “Shroud” Radiocarbon Date Cut from Whole Cloth
March 2, 2005
Longtime Shroud of Turin devotee Ray Rogers, a retired research chemist, now admits there is the equivalent of a watercolor paint on the alleged burial cloth of Jesus. By tortuous logic and selective evidence, however, he uses the coloration to claim the “shroud” image was not the work of a medieval artist (Rogers 2004, 2005). Rogers follows many other shroud defenders in attempting to discredit the medieval date given by radiocarbon testing (Nickell 1998, 150—151).
In a paper published in Thermochimica Acta, Rogers (2005) claims that earlier carbon-14 dating tests—which proved the linen was produced between 1260 and 1390 (Damon et al. 1989)—were invalid because they were conducted on a sample taken from a medieval patch. “The radiocarbon sample has completely different chemical properties than the main part of the shroud relic,” Rogers told BBC News (“Turin” 2005).
In fact, the radiocarbon sample (a small piece cut from the “main body of the shroud” [Damon 1988, 612]) was destroyed by the testing. Rogers (2005) relied on two little threads allegedly left over from the sampling,1 together with segments taken from an adjacent area in 1973. He cites pro-authenticity researchers who guessed that the carbon-14 sample came from a “rewoven area” of repair—“As unlikely as it seems,” Rogers admitted to one news source (Lorenzi 2005). Indeed, textile experts specifically made efforts to select a site for taking the radiocarbon sample that was away from patches and seams (Damon et al. 1989, 611—612).
Rogers compared the threads with some small samples from elsewhere on the Shroud, claiming to find differences between the two sets of threads that “prove” the radiocarbon sample “was not part of the original cloth” of the Turin shroud (as stated in his abstract [Rogers 2005, 189]).
The reported differences include the presence—allegedly only on the “radiocarbon sample”—of cotton fibers and a coating of madder root dye in a binding medium that his tests “suggest” is gum Arabic. He insists the sampled area was that of an interwoven medieval repair that was intentionally colored to match the “older, sepia-colored cloth” (Rogers 2005, 192, 193).
However, Rogers’ assertions to the contrary, both the cotton and the madder have been found elsewhere on the shroud. Both were specifically reported by famed microanalyst Walter McCrone (1996, 85) who was commissioned to examine samples taken by the Shroud of Turin Research Project (STURP). After McCrone discovered the image was rendered in tempera paint, STURP held him to a secrecy agreement, while statements were made to the press that no evidence of artistry was found. McCrone was then, he says, “drummed out” of the organization [Nickell 1998, 124—125; 2004, 193—194]. As evidence of its pro-authenticity bias, STURP’s leaders served on the executive committee of the Holy Shroud Guild.
Not only did McCrone find “occasional” cotton fibers on the Shroud, but the source of Rogers’ sample, Gilbert Raes, has since been challenged as to his claim, cited by Rogers (2005, 189), that “the cotton was an ancient Near Eastern variety.” In fact, others—including French textile expert Gabriel Vial and major pro-shroud author Ian Wilson (1998, 71, 97)—believe the cotton may be entirely incidental. They point out it could have come from the cotton gloves or clothing of the Turin’s cloth’s handlers or a similarly mundane source.
On the tape-lifted STURP samples (affixed to microscope slides), McCrone found a variety of substances (including mold spores and wax spatters). Major pigments were red ocher (in “body” areas) and vermilion (together with red ocher in the “blood” areas), contained in a collagen tempera binder. He also found the madder,2 orpiment, azurite, and yellow ocher pigments, as well as paint fragments, including ultramarine and titanium white—together suggestive of the shroud’s origin in “an artist’s studio” (McCrone 1996, 85, 135)..
Astonishingly—and with serious implications to the spirit of peer review—Rogers omits any mention of McCrone’s findings from his report while insisting elsewhere, “let’s be honest about our science” (Rogers 2004).
Although Rogers is a research chemist, unlike McCrone he is not an internationally celebrated microanalyst with special expertise in examining questioned paintings. Working in his “home laboratory,” he did not, as far as his report informs, use a “blind” approach as McCrone did to mitigate against the subjectivity that has continually plagued the work of shroud advocates. Moreover, McCrone once referred to Rogers’ and his fellow STURP co-author’s “incompetence in light microscopy” and pointed out errors in the test procedures they relied on (McCrone 1996, 157, 158—171).
Rogers (2005) now also reports the presence of vanillin in the lignin of the radiocarbon-sample area, in contrast to its reported absence in other areas of the cloth. This is a dubious finding given his extremely limited samples. He attempts to date the shroud by the amount of the lignin decomposition but admits that that method can offer only an accuracy range of a whopping 1,700 years (contrasted with about 150 years by radiocarbon dating). He concedes that the decomposition could have been accelerated by the baking of the cloth in its reliquary that occurred during the fire of 1532, but thinks it unlikely the cloth is medieval.
However, apart from the fire damage, the cloth is remarkably well preserved for a reputed age of nearly 2000 years. Also, no examples of its complex herringbone weave are known from the time of Jesus when, in any case, burial cloths tended to be of plain weave (Nickell 1998, 35; Wilson 1998, 98—99, 188; Sox 1981). In addition, Jewish burial practice utilized—and the Gospel of John specifically describes for Jesus—multiple burial wrappings with a separate cloth over the face.
Other evidence of medieval fakery includes the shroud’s lack of historical record prior to the mid-fourteenth century—when a bishop reported the artist’s confession—as well as serious anatomical problems, the lack of wraparound distortions, the resemblance of the figure to medieval depictions of Jesus, and suspiciously bright red and picturelike “blood” stains which failed a battery of sophisticated tests by forensic serologists, among many other indicators. These facts argue against Rogers’ assertions that the shroud is neither a forgery nor a miracle—that “the blood is real blood”3 and the image was produced by “a rotting body” (Rogers 2004).
Science has proved the Shroud of Turin a medieval fake, but defenders of authenticity turn the scientific method on its head by starting with the desired conclusion and working backward to the evidence—picking and choosing and reinterpreting as necessary. It is an approach I call “shroud science.”
- Ian Wilson (1998, 187) reported that the trimmings “are no longer extant.”
- Red lake colors like madder were specifically used by medieval artists to overpaint vermilion in depicting “blood” (Nickell 1998, 130).
- Rogers (2004) does acknowledge that claims the blood is type AB “are nonsense.”
- Damon, P.E., et al. 1989. Radiocarbon dating of the Shroud of Turin. Nature 337 (February): 611—615.
- Lorenzi, Rossella. 2005. Turin shroud older than thought. News in Science, January 26.
- McCrone, Walter. 1996. Judgment Day for the Turin Shroud. Chicago: Microscope Publications.
- Nickell, Joe. 1998. Inquest on the Shroud of Turin: Latest Scientific Findings. Amherst, N.Y.: Prometheus Books.
- —. 2004. The Mystery Chronicles. Lexington, Ky.: The University Press of Kentucky.
- Rogers, Raymond N. 2004. Shroud not hoax, not miracle. Letter to the editor, Skeptical Inquirer 28:4 (July/August), 69; with response by Joe Nickell.
- —. 2005. Studies on the radiocarbon sample from the Shroud of Turin. Thermochimica Acta 425: 189—194.
- Sox, H. David. 1981. Quoted in David F. Brown, Interview with H. David Sox, New Realities 4:1 (1981), 31.
- Turin shroud “older than thought.” 2005. BBC News, January 27.
- Wilson, Ian. 1998. The Blood and the Shroud. New York: The Free Press.