invisible reweaving

M. Sue Benford and Joe Marino

There was another hypothesis floating about to explain why the carbon 14 testing might be wrong. It was gaining traction among some shroud researchers and on the internet. Two shroud researchers, M. Sue Benford and Joe Marino suggested that the sample used in the carbon dating was from a corner of the cloth that had been mended using a technique known as invisible reweaving – an actual technique practiced by medieval tapestry restorers and practiced today by tailors to repair tears in expensive clothing.

At the behest of Benford and Marino, several textile experts examined documenting photographs of the radiocarbon samples and found what they believed was visual evidence of reweaving. Based on estimates from these photographs, and based on a historically-plausible date for reweaving, Ronald Hatfield of the radiocarbon dating firm Beta Analytic provided estimates that show that the cloth might be 2000 years old.

Patches applied to the shroud following the 1532 fire were obvious; as noticeable as leather patches sewn to the elbows of an old sweater. Would repairs in 1531 (a plausible date from the historical records) or at any other time, have been so expertly done that that they would have gone unnoticed when the carbon 14 samples were cut from the cloth?

Vanillin Analysis Significant

The chemical differences and the vanillin analysis were significant. Ball, however, was not convinced that invisible reweaving was the underlying explanation. “Well, maybe,” he wrote, then added:

There is no explanation, however, of how the ‘repaired’ threads used in the radiocarbon dating were woven into the old cloth so cunningly that the textile experts who selected the area for analysis failed to notice the substitution. This is by no means the end of the story.”

Indeed, as Ball recognized, “This is by no means the end of the story.”

William Meacham

Currie also raised an important issue of faulty procedures that could have prevented an error from invisible reweaving. According to Currie, the original sampling protocol required multiple samples from different locations on the cloth. Archeologist William Meacham disagrees on historical detail but not scientific principle. In a recent email to about 100 shroud researchers, Meacham stated that the original protocol called for a single sample to be divided among seven labs. He wrote:

Al Adler and I argued forcefully but unsuccessfully . . . for at least a second sample . . . the original protocol was seriously flawed, so it should not be described as some sort of properly designed scientific procedure that was put aside.

Had multiple samples been taken, the chemical differences between the sample area and the rest of the shroud would certainly have been obvious to the labs in 1988.

Rogers blamed church authorities in Turin for not following standard scientific protocol. In the interview with Inside the Vatican magazine, Rogers said:

The sampling operation should have involved many persons from different fields before cutting anything . . . if you really want to get a radiocarbon data, take a lot of samples.

Red Flags Ignored

There were other clues, as well. All of them were warning signs that something might be wrong with the carbon 14 samples:

• Giovanni Riggi, the person who actually cut the carbon 14 sample from the Shroud stated, "I was authorized to cut approximately 8 square centimetres of cloth from the Shroud…This was then reduced to about 7 cm because fibres of other origins had become mixed up with the original fabric …" (emphasis mine)
• Giorgio Tessiore, who documented the sampling, wrote:  “…1 cm of the new sample had to be discarded because of the presence of different color threads.” (emphasis mine)
• Edward (Teddy) Hall, head of the Oxford radiocarbon dating laboratory, had noticed fibers that looked out of place. A laboratory in Derbyshire concluded that the rogue fibers were cotton of “a fine, dark yellow strand.”  Derbyshire's Peter South wrote: “It may have been used for repairs at some time in the past…”
• Gilbert Raes, when later he examined some of the carbon 14 samples, noticed that cotton fibers were contained inside the threads, which could help to explain differences in fiber diameter. This may also explain why the carbon 14 samples apparently weighed much more than was as expected.
• Alan Adler at Western Connecticut State University found large amounts of aluminum in yarn segments from the radiocarbon sample, up to 2%, by energy-dispersive x-ray analysis. Why aluminum? That was an important question because it is not found elsewhere on the Shroud.
• The radiocarbon lab at the University of Arizona conducted eight tests. But there was a wide variance in the computed dates and so the team in Arizona combined results to produce four results thus eliminating the more outlying dates (reportedly they did so at the request of the British Museum, which was overseeing the tests). Even then, according to Remi Van Haelst, a retired industrial chemist in Belgium, the results failed to meet minimum statistical standards (chi-squared tests).  Why the wide variance in the dates? Was it because of testing errors? Or was it because the sample was not sufficiently homogeneous? The latter seems very likely now, and the statistical anomaly indicates something very suspicious about the samples.
• Bryan Walsh, a statistician, examined Van Haelst’s analysis and further studied the measurements. He concluded that the divided samples used in multiple tests contained different levels of the C14 isotope. The overall cut sample was non-homogeneous and thus of questionable validity. Walsh found a significant relationship between the measured age of various sub-samples and their distance from the edge of the cloth. Though Walsh did not suggest invisible reweaving, it is consistent with his findings.

Mechthild Flury-Lemberg a Holdout

Mechthild Flury-Lemberg, who directed a controversial restoration of the shroud in 2002, was another holdout. During the restoration she had not seen any evidence of repairs and stated that “reweaving in the literal sense does not exist” and that any such reweaving would be visible on the back side of the cloth.

But the invisible reweaving art did exist. It existed in medieval Europe just as it does today.  In a peer-reviewed paper presented at the Third International Dallas Conference on the Shroud of Turin in September, 2005, Benford and Marino explain why the repairs may not have been noticed. And they corrected Flury-Lemberg’s statement that any such repair would have been visible on the back side of the cloth.