Monday, January 30, 2012

The Turin Shroud - a bit of bas-relief

Multiple thermo-imprinted images from a single bas-relief template obtained as the trinket cooled down

Yes. I've given up on thermo-stencilling for a bit (see previous posts) and am now experimenting with bas-relief. So far I've merely repeated what John P Jackson of the STURP team and others have done - which was to produce a scorch mark on untreated linen with a heated bas-relief object (in this case a trinket I picked up while in Ghana). Yup, I know that the Turin Shroud is not a scorch mark according to the admirable Raymond N Rogers (RIP). But Rogers was not infallible - indeed I shall shortly be putting some of his experiments and conclusions under a fellow (bio)chemist's, er, microscope, and in any case Rogers only said it was not a scorch onto bulk fibres in linen. But that did not preclude the possibility that it was a thermal - or maybe chemical imprint onto a superficial layer of something else that was more thermo-sensitive than cellulose, as Rogers himself proposed. eg. starch, or simple hexose or pentose sugars.

However, experimental work will have to be put on the back burner for a while (literally).   I am presently composing a critical overview of another paper that has been pushed under my blogging nose, namely that of Fanti et al on the use of computers to re-image the "true" (ho ho) ventral and dorsal  ("front and rear") anthropomorphic dimensions of the image on the Shroud.


sciencebod said...


sciencebod said...

Here's a comment from another site that I decline to respond to there, on the grounds that people who cannot be bothered to ask one to enlarge on one's views, who impute ludicrous positions that one has never articulated, are simply unpleasant and/or dangerous to know. Anything one says is likely to be further misinterpreted or distorted.

"I can understand someone arguing that the 3D information in the image wasn’t created by an actual 3D body – ie, that the image was deliberately fabricated somehow to *seem* 3D by shading areas such that their hue would correspond with their depth on a real face. I don’t believe that, or think it’s even a tiny bit plausible given what we know about the Shroud, but at least it’s a logical statement. If, on the other hand, sciencebod is really trying to say that the 3D encoding is all an illusion, that it’s just pure luck that it has the appearance of depth and that plotting the depth based on hue with a computer produces such an accurate 3D image of a face, based on the fact that the burn holes produce a variation in hue as well, then he’s simply nuttier than a Snickers bar, and it’s amazing that anybody is wasting more than a single breath dismissing his idea as less than wrong."

This same point was covered in a brief exchange I had on another post with "C", posting here as Anonymous.

Direct contact with a heated bas relief object produces a thermal imprint, i.e. a scorch. If a means can be found for producing an image with graded scorching, instead of a rather abrupt either/or effect (as in my picture above) then densitometric scanning of the scorched-on image may well yield a reasonable 3D effect with the appropriate imaging software (VP-8 etc). If burn holes with graded scorching do so, then intentionally-imprinted images are likely to do so also...

The flaw with the simple experiment as described above is that it uses uncoated linen which is largely cellulose, requiring intense heat to produce a scorch, with little or no subtlety in the scorch.

The next step, as suggested, is to coat or impregnate the linen with agents that tend to brown more easily. I might even try lemon juice for starters to replicate the well-known "invisible ink" effect, and then try modifying that perhaps by mixing the lemon juice with gels or gums, recalling that Raymond Rogers considered the Shroud image to be confined to a cuticle like layer on the linen that could be stripped off, image and all, with adhesive tape. Indeed, some, indeed most may already have peeled of naturally, leaving just a pale imprint at the interface of cuticle and linen.

That model could explain the weak image on the reverse side too, if one imagines that sufficient heat conducts across the cellulose layers to affect the far side, while being insufficient to degrade or disturb the cellulose fibres en route.