What on earth happened – or should I say didn’t happen – on 20th August 2024? Out of a blue sky, a sudden media frenzy erupted around a previously largely unnoticed piece of research carried out by some Italian scientists two to five years previously. Entering “Shroud” “Turin” and “WAXS” into the Google search bar displays a number on the top right of the screen – “About 5,380 results.” By limiting the search to a specific time, we can break that number down into the days when all these results were posted, although Google’s algorithms vary the precise details, so the numbers tend to change every time you check them. As of today (10 September), here are the counts for five weeks this summer:
And now we seem to have returned to a more characteristic somnolence. The Shroud never goes away, and there are new videos, in particular, posted every day, but they rarely hit the headlines.
Anyway, the excitement was stimulated by the belated discovery, by some bored hack or other, of the papers by Liberato de Caro et al., regarding the possible dating of old textiles by means of Wide Angle X-Ray Scattering, or WAXS, which I covered in some detail in a couple of posts at the time it was published. They are both called “WAXSing and Waning,” should anyone care to revise my review.
What has stimulated this post is a recent interview with Liberato de Caro, who was the lead author of ‘X-Ray Dating of Ancient Linen Fabrics’ and ‘X-Ray Dating of a Turin Shroud’s Linen Sample,’ both published in Heritage, in November 2019 and April 2022 respectively, the papers which have attractted all the recent attention. The interviewer was Cameron Bertuzzi, the host of Capturing Christianity, a professional photographer, and the interview itself was conducted by email, although the emails are voiced by Bertuzzi and a generic AI Italian, which is slightly unnerving.
De Caro is an X-Ray imaging specialist with dozens of papers to his name, and although the idea that you might be able to date textiles by WAXS is new, none of the laboratory techniques involved are unconventional. If there are criticisms of his findings – and there are, lots of them – they are not of his methods or results, but the conclusions he draws from them.
The first interesting thing de Caro says is that he has performed a blind dating test. A cloth sample whose date was known, but not to the investigator, was analysed by WAXS, the result compared against the calibration graph derived in X-Ray Dating of Ancient Linen Fabrics, and the corresponding date found to concur with the known date of the sample. It is a pity that he gives no further details of this, and that Bertuzzi doesn’t ask for any. As such it is not very helpful. The calibration curve is not particularly clear, and based almost entirely on samples from mummies in Egyptian and Middle Eastern tombs, whose environments have been fairly constant. A sample from a similar environment might well fit the curve. We are also not told how precisely it correlates. For example, an ‘aging factor’ of about 11.5 covers the years from 300 BC to 3000 BC, so should an aging factor of that value have been obtained, and the fabric date from about 2000 BC, we can hardly be too triumphant about it.
De Caro goes on to say that the most convincing thing about his experiments with the Shroud is how exactly it correlates with a textile from Masada. Unfortunately, this, for me, is one of the least convincing. For a start the correlation is not strictly precise, and for a second, such a correlation is only meaningful if the two textiles have been kept in identical environments. Let’s examine the first:
In this read-out, A is a modern, bleached, linen, D is from Fayum, Egypt, FII is from Masada and LII is a 5000 year old fabric from Egypt. TS means Turin Shroud. The first thing we notice is that in the first four cases, the graphs show the same order in their intensities from top to bottom right across the graph, or at least from when they untangle from each other at about 6nm-1. Black, red, green, blue, from 6nm-1 to 18nm-1. Not so of the Shroud.
At 6nm-1: – SHROUD, black, red, green, blue.
At 9nm-1: – Black, SHROUD, red, green, blue.
At 12nm-1: – Black, red, SHROUD, green, blue.
At 15nm-1: – Black, red, SHROUD, green, blue.
At 12nm-1: – SHROUD, black, red, green, blue.
For meaningful comparison, the fact that the Shroud graph is somewhat flattened with respect to all the others ought to be explained before it can be said to compare to any of them. For the second point, the Masada textiles were buried in 65 AD, and remained undisturbed until they were discovered almost exactly 1900 years later. Their degradation might be supposed to be slow and steady. The Shroud has been moved from Lirey to Chambéry to Turin, not to mention sojourns in other European towns, folded and unfolded, soaked with water and charred in fire. I would expect its degradation, with respect to fabrics kept in constant environments, to make it look much older than its real age. Finding that it exactly matches Masada in fact suggests that it is much, much younger.
Next, Bertuzzi asks about the effect the fire of 1532 may have had on the Shroud, and de Caro explains that the WAXS profile of a piece of linen kept at 200°C for half an hour is essentially identical to that of a piece of linen kept at room temperature. I think this is almost incredible, and suggest that the experiment be carried out again, and with additional parameters. How long, I wonder, does it take before any change is observed? I’m afraid I do not find the idea that, entirely fortuitously, the deleterious effect of the increased temperature is exactly balanced by the beneficial effect of the reduced humidity, at all convincing. Here is the graph of the two experiments, showing the exact overlap.
Furthermore, there is a discrepancy between the graphs obtained from the heating experiments from those obtained from the comparison experiment. The heating experiment was carried out on a piece of modern linen, so, if we superimpose the two graphs above, the modern linen lines should be the same. Here, to demonstrate the accuracy of the superimposition, are the two graphs:
The purple lines show the equivalence of the x- and y- axes. It is not easy to compare these, so here is the ‘heating’ graph, superimposed alone, as a dotted line, on the others.
There is a distinct and significant difference between the solid black line of “A (2000 AD)” and the dotted black line of “Linen no heat” and “Linen heat at 200°C for 1800s.” There are numerous possible explanations for the difference, but none of them give me confidence in these experiments.
I’ve no idea why Bertuzzi next asks why de Caro chose 200°C rather than, say, the actual combustion temperature of linen. I should have thought it was obvious that you can’t test a pile of ash. However, it leads to one of those interesting “let’s believe everything” conundrums that occasionally crop up in sindonological discussions. De Caro is at pains to explain that the radiocarbon corner area was “very far from [the cloth’s] burned regions,” whereas famously Alan Adler claimed that the sample was from “an obviously water stained area just a few inches from a burn mark” (The Orphaned Manuscript, p. 82). You pays your money…