At the same time as composing a (serious) critique of the Rogers’ so-called “vanillin” clock (a misnomer if ever there was, as I shall be explaining shortly), I’ve been fielding objections on shroudstory.com to the scorch hypothesis.
Serendipitously, I came across a photomicrograph in the Rogers’ paper, a curious choice on his part, given its caption, one that I wish I had spotted earlier when discussing mechanisms by which a linen fibre can acquire a scorch, and more importantly, which parts of the fibre are affected, and with what consequences re colour distribution, mechanical strength etc.
Here’s a screen grab of the graphic in question:
Note carefully the caption (ignore the blue highlighting): it says it’s ” a colored image fiber from the back of the ankle (x400 magnification)”, and that it was obtained by pressing adhesive tape against the Shroud in the 1978 STURP visit to Turin.
We are asked to focus attention on the nodes, that are darker on account of lignin, or rather degraded lignin that has lost its ability to give a colour with the Wiesner reagent (phloroglucinol/HCl) due to alleged loss of vanillin.
Let’s skip the vanillin story for now, and the wisdom of choosing an image fibre on which to propose a “vanillin clock” for estimating age (who’s to say that it was not the imaging process that degraded the lignin in that photograph?). Something else struck me when looking at that picture. If indeed the image fibres can be said to be coloured in that photograph, then the colour is not confined entirely to the exceedingly thin outermost layer, i.e. the primary cell wall (PCW), allegedly a mere 100nm thick – incidentally a figure consistent with the alleged thickness of the detachable image layer in Rogers’ “ghost stripping” experiments. It is also visible (apparently) in the cores of the fibres too – i.e. the thick secondary cell wall (SCW) albeit as a weaker intensity. That may come as a surprise to those who might have expected all the colour to reside in the PCW, based on those highly-reported stripping-away-from-adhesive experiments, leaving behind coloured so-called ghosts that were estimated to be less than 200nm thick (based on inability to see them edge-on in a light microscope). But it came as no surprise to this sceptical scorch-promoting blogger, since only yesterday I re-posted a diagram I had prepared for a posting several months ago. It showed the expected colour distribution, based on the fact that the scorch-susceptible hemicelluloses are not confined entirely to the PCW, but represent an appreciable fraction of the SCW too (some 15%, the rest being mainly crystalline celluloses that are far more resistant to pyrolysis and scorching).
Link to previous posting (now over a year old) which incorporated the above graphic as home-made “visual aid”
Now for the take-away message: there is now an explanation for why Shroud image fibres are mechanically weaker than control non-image fibres. That would not be the case (surely?) if it were only the exceedingly thin outer PCW that was scorched and partially-degraded. But it would be likely to be the case if 15% of the core carbohydrates were similarly scorched, even if the remaining cellulose largely escaped serious physical or chemical modification.
Here’s the actual quotation from the multi-author Fanti et al paper, one I reminded people about yesterday on Dan Porter’s site and which served as a cue for making a connection between the visual, chemical and mechanical properties of linen fibres in terms of their coaxial PCW/SCW structure.
Anyone who still thinks that the Shroud image was produced by biological action (especially on an acquired impurity layer, as in Rogers’ Maillard reaction hypothesis) has to explain why that would cause mechanical weakening of the entire fibre – to say nothing of why there has so far been no convincing demonstration – or even search for – some chemical signatures in the image regions, e.g. extra nitrogen from putrefaction amines.
Afterthought: this posting can be seen as a refutation of the idea, fostered by those sticky-tape experiments of Rogers (also Heller&Adler) and the introduction of the notion of image ghosts 200nm or less in thickness, that the Shroud image is ENTIRELY in a superficial coating or layer on the fibre surface. That may be where most of the image intensity lies or is most easily detectable. But if image represents pyrolysed hemicellulose, then a lot more could exist throughout the entire core of the fibre, but be less visible under the microscope on account of those SCW hemicelluloses representing just 15% of the total carbohydrate. But 15% degradation would be sufficient to make it mechanically weaker, given that the SCW is a composite structure that depends for its strength on both rigidity (crysalline cellulose) and a degree of pliability provided by cement material (rather like man-made composites with fibres embedded in a resin, where the integrity of both components is required).