New Mysteries of the Shroud of Turin

The Shroud of Turin was generally regarded as debunked in 1988, when radiocarbon tests dated its material to the 14th Century, well after the time of Christ and suspiciously near to that of its first known custodian, Geoffroi de Charnay, Seigneur de Lirey. Given the medieval propensity for producing fake relics, it was easy to believe that this was another one, albeit more imaginative than pieces of the True Cross or samples of the Virgin Mary’s breast milk. One puzzle remained: How did the forger produce the images on the cloth, which resemble photographic negatives and are unparalleled anywhere else? Nobody had a good answer, but, though the Shroud retained a core of believers, filling in the details of how the fraud was accomplished didn’t seem like an urgent task.

Three recent developments may, however, bring the Shroud controversy back to life.

First, a detailed study of the Shroud images (Giulio Fanti & Roberto Maggiolo, “The Double Superficiality of the Frontal Image of the Turin Shroud”, 6 Journal of Optics A: Pure and Applied Optics, 491-503 (2004) [abstract] [PDF]), based on photographs taken when parts of the cloth were temporarily unstitched in 2000 and 2002, suggested that they were odder than anyone had realized. In the investigators’ words,

The face image is therefore doubly superficial. This means that, if a cross-section of the fabric is made, one extremely superficial image appears above and one below, but there is nothing in the middle.

This phenomenon is another obstacle to devising a theory of the Shroud’s origins that fits all of the facts and is purely natural.

Second, in January of this year, Thermochimica Acta, a peer-reviewed journal, published an article questioning the 1988 radiocarbon findings (Raymond N. Rogers, “Studies on the Radiocarbon Sample from the Shroud of Turin”). The author’s comparison of the chemical properties of the bits of the Shroud used by the radiocarbon analysts with other portions of the cloth led him to conclude that their samples came from late patches, not from the original fabric.

As unlikely as it seems, the sample used to test the age of the Shroud of Turin in 1988 was taken from a rewoven area of the Shroud. Pyrolysis-mass spectrometry results from the sample area coupled with microscopic and microchemical observations prove that the radiocarbon sample was not part of the original cloth of the Shroud of Turin. The radiocarbon date was thus not valid for determining the true age of the Shroud.

These two developments were welcome to Shroud believers, who trumpeted them loudly. The third and most recent, relayed by Cronaca, will please them less. Discovery News reports,

The Shroud of Turin, the piece of linen long believed to have been wrapped around Jesus’ body after the crucifixion, could have been easily forged by painting an image on glass, according to an experiment reported today in the magazine Book and Culture. . . .

Nathan Wilson, a fellow of literature at New St. Andrews College, Moscow, Idaho, claims to have successfully created a shroud-like image. . . .

Helped by microbiologist Scott Minnich, an associate professor at the University of Idaho, who provided him with scientific advice on structuring the experiment, Wilson put fabric under a glass panel painted with a human face — using white paint — and left it in the sun for a few days.

Wilson found that when a positive image of a man's face was painted onto glass, and left over linen beneath the sun, a color inversion took place, creating a photo negative.

“Wherever light paint had been applied, the linen remained dark beneath, and wherever the darker shade of linen had been left bare, the image lightened. In this regard, the image produced is very similar to that of the Turin Shroud,” Wilson told Discovery News.

In addition, the rising and setting of the sun — exposing the image from nearly one hundred and eighty degrees — encoded the image on the cloth three-dimensionally.

“The images are stunning. This is just a method, it does not mean this is how the original shroud was produced. But it explains how natural causes may have produced the images on the shroud, versus supernatural causes,” Minnich said.

According to Wilson, it would have been easy for a medieval forger to create an image similar to the one of the Turin Shroud using his method.

The full article, “Father Brown Fakes the Shroud”, describes the experiment in exhaustive detail.

For seekers of hidden agendas, it should be noted that Mr. Wilson is a conservative Protestant. He serves as managing editor of Credenda/Agenda, “a bimonthly periodical exploring all areas of life from a biblical, classical Protestant perspective” and is the author of a take-off on the theologically dubious Left Behind novels, entitled Right Behind: A Parody of Last Days Goofiness. He is not, in other words, someone who is likely to be invincibly prejudiced against the idea that Jesus’ genuine burial garments might have survived the centuries.

His experiment seems, however, to have a couple of weaknesses. His hypothetical forger needed a large sheet of plate glass; the Shroud image is 5’ 7” tall. In the 14th Century, when glass was an expensive luxury good monopolized by Venetian craftsmen, the cost of obtaining over ten square feet would have been enormous (more than enormous if Mr. Wilson’s technique requires uncolored glass, then a rarity). We are then to suppose that the buyer defaced this precious surface with paint in order to create his relic. That is a lot of trouble and expense to undertake in an era when very crude productions were sufficient to fool the credulous.

Moreover, the double superficiality of the image is a perplexing and unnecessary complication. To create it, the forger would have to first expose the front of the cloth, then turn it over, reverse the glass covering, taking care to align it precisely with the now invisible front image, and repeat the exposure. Why would he bother? Did he miraculously anticipate investigations by post-Enlightenment skeptics?

So my initial reaction is that Mr. Wilson has not shown that “it would have been easy for a medieval forger to create an image similar to the one of the Turin Shroud using his method”. That method may be physically possible, but it fails any plausibility test. Whether or not this antique cloth is the funeral wrapping of Our Lord, the mystery surrounding it persists.

Update (3/7/05): Cronaca has added an extensive update to its original post, which has inspired further thoughts on my part.