Also, in reference to the posting, “Joe Marino, Sue Benford and the Carbon Dating of the Shroud of Turin « Shroud of Turin Blog,” Maria da Glória Gonçalves Barroso of the Centro Português de Sindonologia makes a very important point.

I had written:

Material intrusion is a big problem in carbon dating. Students of radiocarbon dating technology are familiar with classic examples. For instance, it is almost impossible to date a sample from a peat bog when it is a mixture of decayed newer plants that grew (materially intruded) into older decayed plant matter. And there is the known problem of dating snails living in an artesian spring in Nevada. They were found to be “27,000 years old” at the moment of death because their shells were formed from existing ancient bicarbonate (materially intruded) that was depleted of much of its carbon 14.

Not only had Benford and Marino provided a theory, if not proof, that the carbon dating of the shroud was invalid because of material intrusion, they provided a new, surely more famous, example of material intrusion for radiocarbon dating education. Call it an instant classic example. But the lesson is bigger than that. Students and practicing scientists of radiocarbon technology need to wonder how so many scientists didn’t anticipate the problem given that there were ample warning signs at the time. . . .

Maria da Glória writes:

This post pointed out an important fact dealing with intrusion material which I can’t help quoting “so many scientists didn’t anticipate the problem given that there were ample warning signs at the time.”

As far as I remember no one mentions Dr. John Tyrer’s advice on that matter, but I think it’s worth remembering.

Dr. John Tyrer a british textile expert published an article on the Shroud in textile journal Textile Horizons December 1981 entitled «Looking at the Shroud of Turin as a Textile» and after analyzing photographs of the Shroud ,just by looking at the place where Raes sample had been taken he stated “There is therefore some doubt as to wheter the sample described by Professor Raes as Piece II is the edging strip or part of a patch.IT IS IMPORTANT THAT THIS MATTER BE RESOLVED IF IT IS INTENDED THAT THE FORTHCOMING CARBONDATING TESTS ARE TO BE MADE ON RAES SAMPLE.THE PATCH IS PROBABLY MEDIEVAL.”

This was written in 1981. Is this the first clue to help invalidate radiocarbon test dating of the Shroud?

I guess radiocarbon labs ignored this advice.

If someone is interested to read it the article is available in scientific articles.

This belongs in any history of the carbon dating of the Shroud of Turin. Thanks for bringing this to our attention.