Early Clues Something Was Amiss in the Carbon 14 Dating

This page is best understood by first reading the page, Failure in Radiocarbon Dating the Shroud of Turin.

One early clue that something was wrong came from Alan Adler, a professor of chemistry at Western Connecticut State University. He found significant levels of aluminum in yarn segments from the radiocarbon sample area, up to 2%, by energy-dispersive x-ray analysis. Why Aluminum?

Raymond Rogers, a chemist from the Los Alamos National Laboratory would later answer that question in his seminal paper disproving the carbon 14 dating. The aluminum was in the form of hydrous aluminum oxide or alum, a common mordant used with dyes. Spliced-in new threads used to repair the shroud had been dyed to match older age-yellowed thread.

Adler had examined a fragment of the carbon 14 sample and compared it to fibers from elsewhere on the shroud. He used both Courier Transform Infrared Microspectrophotometry and a Scanning Electron Microscope. "The results clearly indicated differences in chemical composition," he wrote. The samples were clearly not representative. 

In 1988, Edward Hall, then director of the Oxford University Radiocarbon Laboratory, had found cotton fibers that might be from mending.

So did P. H. Smith, a consultant to the Oxford lab. He later wrote an article for Textile Horizons called "Rogue Fibers Found in Shroud," Smith suggested that those cotton fibers were suspicious and might have been part of repairs.

Giovanni Riggi, the person who 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 added) 

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 added)

The Arizona lab made eight measurements with dates that varied widely. The clearly suggested that the sample was not homogeneous. Rather than deal with the problem, the British Museum asked Arizona to discard the four outside measurements and use only those that were most similar. It was the only way they could calculate a satisfactory error distribution.

Ultraviolet and x-ray photographs, taken in 1978 before the carbon 14 dating samples were taken, showed that there were chemical differences between the sample area and surrounding areas of the cloth.

No all of these clues, but just a few, were enough to cast reasonable doubt on the radiocarbon dating of the Shroud of Turin. But this information was held back when the results were made public.

Other Clues

Clues from Vanillin Content