Ten good reasons for thinking that the Shroud image resides on an impurity layer, as proposed by explosives chemist Raymond N.Rogers

Sorry, but this retired science bod cannot think of a single good reason for thinking the Shroud image is on an impurity layer, whether it be starch, semi-degraded starch, soapwort, saponin, aloes, myrrh, whatever.


Nope. I'm not talking now about anecdotal evidence based on the supposition (at odds with the radiocarbon dating) that the Shroud is of 1st century AD provenance, when starch and/or natural soaps were allegedly used in spinning and weaving or bleaching.

I'm talking about hard chemical and other evidence, such as was acquired by the STURP team, to which the late Raymond N.Rogers was seconded as lead chemical investigator.

But you will not find Rogers' impurity coating thesis mentioned anywhere in the 1981 STURP summary of findings  - and rightly so in my opinion.

OK, so playing hunches has a vital role in science ("framing hypotheses") but they have to be (a) testable in principle if they are to be taken seriously and (b) tested in practice before they can be accepted into the mainstream of scientific thinking.

 Rogers' impurity coating idea not only lacks for hard experimental data, but the further development as his "Maillard reaction" hypothesis, proposing reaction between putrefaction amines(largely unspecified) and reducing  sugars (largely unspecified) appears to this sceptic as pie-in-the-sky.

More importantly, the idea has never been properly put to the test, unless one accepts at face value the results of a questionable experiment involving ammonia and a contrived mix of (conveniently) partially-degraded starch ("dextrins"), providing the needed "reducing sugars" that intact starch is lacking. The yellow colour, assumed to be a Maillard product (evidence?) is open to alternative interpretation, given the absence of required controls, e.g. on pH (recalling that ammonia is a base, as well as a nitrogen donor). The elevated temperature (66 degrees Celsius) used to obtain a reasonable rate of reaction (or thermodynamic feasibility?) does nothing to cement credulity if intended as a model for natural processes occurring in and around a fairly recently-deceased shroud-wrapped cadaver.

  Sorry,  I'm going to have to end here for want of hard scientific data. Sorry if the title misled. Sometimes the means do justify the ends- like deliberately derailing a  (now) driverless runaway locomotive before it's picked up too much speed.

Apologies in advance to those who think I have misjudged Raymond N.Rogers (RIP). Maybe I have overlooked crucial scientific evidence that  underpins his "impurity layer" hypothesis. If so, please feel free to comment.

In the meantime, this Shroud investigator will continue to regard the hemicelluloses of the primary cell wall (PCW) as the most likely target for the image-forming mechanism, and sees no need, absolutely no need, to assume that untreated linen, free of starch and/or other processing aids, modern or classical, is incapable of accepting an image onto its intrinsic PCW, e.g. via direct physical contact with a heated metal template.

Postscript: I see that Adler's observation that diimide, NH=NH, bleaches the Shroud image, is being adduced as evidence in support of Rogers' ideas. I fail to see why (being unmoved  by references to whether linen fibres look "clean" or "undamaged" before or after diimide treatment). What's the connection between events at the molecular level, and those at the gross one, with or without the benefit of a light microscope?

Second postscript:  It's been suggested  elsewhere that there is no way of telling whether the Shroud image is on the PCW or on a more superficial impurity coating. Admittedly that may be difficult using classical microscopy (atomic force microscopy is another matter). But it's not impossible using chemical means, though access to Shroud samples in the quantities required is as problematical as ever.

In fact I reminded folk last year of the technology that is available. It involves chemical hydrolysis of image v non-image areas via different graded acid-pretreatments, followed by  gas-liquid or HPLC separation of constituent starch and cell wall sugars. An image on the PCW  that resulted in partial or complete pyrolysis of the heat-sensitive hemicelluloses would be detected as a loss of hemicellulose markers (glucoxylans and other non-starch, non-cellulosic pentosan sugars etc) in the image-bearing samples relative to non-image controls. Alternatively, a putative image on a starch coating etc would be expected give the same profile of intact PCW sugars in image v non-image areas, with differences appearing in the additional complement of acquired starch etc, giving differences between the glucose recoveries.