Continued modelling of the Turin Shroud image: two alternative options for flour-assisted thermal-imprinting - both feasible, but neither without its difficulties

“Models are to be used, not to be believed"

Henry Theil (economist)

Here's a photographic record of the experiments conducted this Sunday morning in my humble home laboratory - or what my wife continues to refer to tediously as "her kitchen".

See the postings immediately preceding this one for how we come to be where we're at this present point in time. It's been a long journey (getting on now for 3 years - see this blogger's first Shroud posting).

Here we go again. This is the Mode 1 option (see previous posting) in which the white plain flour is sprinkled  onto the linen, then lightly brushed in. The brass bas-relief  template is to be heated and pressed into the flour-coated linen.

End-result: a very satisfactory thermal imprint, aka scorch. Note the lack of sharp definition,, a bonus of sorts maybe.

Close-up of Mode 1 'fuzzy' image. Improved model for the TS, given that some say scorch imprints are too sharp and well-defined?

First step in deploying the alternative Mode 2 option. Coat the template with white flour, having first applied a thin smear of vegetable oil

Press the coated template into linen

After impression. The flour imprint on linen not yet visible in this pic until next stage (roasting).

First sign of an image appearing on roasting

Image now becoming more apparent, even if not immediately recognizable as a horse brass.

One can now see the outlines of the horse brass, even if it's not clear there's a crowned head of state (Queen Elizabeth II's dad, George thethethe VIth).

The monarch's head is still not obvious. Maybe the technology needs to be refined.

Time to run  a control - oil without flour.

Close up of oil-only imprint.

Even oil alone gives a vague image of sorts - but it's nowhere near as sharp as a flour image, making a  super-fuzzy flour/OIL imprint even MORE credible, given the ghostly character of the TS image.

Preliminary conclusions:  

Mode 1 imprinting with a hot template onto flour-coated linen is by far and away the easier of the two options, at least on a small-scale. What's more, the image is much fuzzier, and dare one say more Shroud-like, than comparable images on plain untreated linen. Need one look further? Might flour-coating and hot template imprinting have been the simple technology that was employed some 650 years ago? Is the TS image primarily a Maillard product, the result of chemical reaction between reducing sugars and protein - not a simpler thermal decomposition product of pyrolysed linen carbohydrates requiring no amino-nitrogen (-NH2) whether from proteins or post mortem decay?

But simpler technology in what sense? Merely because the image-making process can be targeted to particular areas of linen by means of a heated template? It's one thing to heat  horse brass to temperatures between 220 and 250 degrees C, and  manoeuvre  into position,  another to do the same with a life-sized effigy.

So might it have been Mode 2 technology that was chosen?

It has clear advantages over Mode 1, in that ANYTHING with 3D properties can in principle be imprinted, not having to be heated. That might be bas relief templates and/or fully 3D statues.  It may even conceivably have been a person, living or dead.  All that was needed was a coating of white flour (or a comparable dry powdered substance providing reducing sugar and amino groups), probably with a binder material to ensure adhesion and even coating (the vegetable oil in the present modelling, but other options exist).

But there's a tricky step in the procedure - namely the final roasting of the flour-imprinted linen that has to convert the coating to tan-coloured melanoidins (Maillard reaction products) without too much discoloration of the linen. It can be done in  principle, on a small scale laboratory basis, given the exceptional chemical and thermal stability of cellulose, by far and away the major component of linen fibres, relative to the the starch, proteins, lipids, non-starch polysaccharides etc of white wheaten flour. But an entire burial shroud?

There's a great deal to think about right now. Best maybe to stop here and post the experimental results. Perhaps others can see things I have missed that might offer a way forward through this thicket of new possibilities, each with its own unique potential (and accompanying difficulties).

To those who claim I select and/or manipulate experimental data I say this. Go boil your heads (old English expression of endearment).

Monday 27 October

By way of postscript, I must add that my thinking is changing by the minute as a result of re-adjusting to the idea of the TS body image being heterogeneous, as shown by its two-tone character.

I'd previously suggested that the rosy regions represented the highest points on the 3D relief of a template. (Let's not concern ourselves too much right now as to the precise nature of the template). But the nose is not rose coloured like the cheeks, chin, chest and shoulder blades. Why not, given its prominence where facial anatomy is concerned?

 What's more,  there's poor correspondence between a  map of rosy colour and that of the same Halta image in ImageJ in Thermal LUT mode,  using the latter as a probe of image density, and accordingly serving provisionally as an indication of presumed 3D relief (used cautiously). I may add some graphics here later to document those statements.

One could argue, of course, as Luigi Garlaschelli has done, that a bas relief would need to have been used for the face to achieve imprinting without excessive lateral distortion, and that's a view with which I have long concurred.  But there's another possibility, prompted by what I see on so many flour imprints, in either of the two modes, namely that the regions of rosy colour are where there has been greater thickness of hypothetical flour (Mode 1) or greater adhesion of that same flour to the template (Mode 2).


Update: 17:45  October 27th

There's a distinctly bad smell coming from the world of shroudology right now, and has been ever since that pseudo-conference in St.Louis dumped still more pseudo-science on us all, lauded through the usual channels.

Am now taking a break from shroudology for a while.

I'll still be researching my Maillard-assisted  imaging with the flour, and be thinking through the wealth of new options it opens up, maybe drafting some new posts. But  I shan't be reporting, not any time soon, much as I would like to. Time to head for the hills - the air's cleaner there.




Reminder:I have consistently stated from the start of this project that my objectives are limited. There is no aim or ambition to re-create the TS image, as we sceptics constantly find ourselves challenged to do so. Whilst having the greatest admiration for those who have attempted that, and who indeed, notably Garlaschelli certainly exceeded my own expectations of what can be achieved by 3D ->2D imprinting, my own goal is more modest. That is to respond to the claim that the TS image is uniquely subtle as regards superficiality and microscopic properties. In other words, it is primarily the scientific principles that interest me. Was a supernatural event really required, as claimed by those ENEA self-styled 'scientists' (?). Had they really done a long thorough job in excluding conventional science as they claimed three years ago in their press releases?

I have arrived a modified scorch hypothesis that sees a role for an adjuct, namely a binary mix of Maillard reaction precursors, one that serves to sensitize linen to heat. Straightaway one can  easily model TS-like images that have that peculiar fuzziness to them. It's only a first step, but an important one, given the focus some have placed on image definition.

I have informed folk of the scientific basis of this new approach. White flour was arrive at entirely via a scientific route, one that started with an investigation of the invisible ink effect with lemon juice, and then linked that as others have done to  Maillard chemistry (not acid etching). That train of thought then converged with a separate one based on image analysis*, using especially the Halta Definizioni image on the BBC site.

* To which a technical appendix on my approach and methodology was placed yesterday on the second of two postings.

 No Dan Porter, I am not a small boy playing with flour, and your continued attempts to infantilize do you no credit whatsoever. Nor does your attempt to block free speech. Nor does your tolerance of trolls on that site of yours who specialize in making character attacks.

Go boil your head, Dan Porter. I'm heartily sick of you and your tedious popgun attacks, 

  Wednesday 29 October

I have spotted Dan Porter's response to my comment above. An apology is not to be lightly dismissed, and to do so would be ungracious. Nevertheless, I consider there are serious issues that remain unresolved regarding the instant reporting of ongoing research, and the kind of comments that appear from certain individuals, albeit a minority, who collectively might be called a mean-spirited knocking brigade. 

One suspects they take their cue from the slightest hint from a blogmeister that the new research is in his view not quite up-to-scratch. It's those instant judgements that encourage the trolling element, and which also probably inhibit those who might wish to initiate and/or engage in a freer less-partisan debate that does not instantly pre-judge. 

I shall say no more for now, if only because I'm trying in spite of everything to stay focused on the task in hand, which is to decide if the key to the peculiar TS image was the use of a powder barrier of some kind between a heated template and linen, and if so, whether that barrier substance was chemically prone itself to scorching (e.g. white flour),  or was chemically inert, acting merely as a thermal barrier to over-rapid heat conduction (powdered chalk?).

I'm running some further tests in an attempt to get a handle on this question, but don't expect instant results, and don't expect future findings to be instantly reported, if all that does is to elicit instant knee-jerk put-downs.

 After some 3 years of writing real-time research reports, this blogger/experimentalist is now a sadder but wiser man where the internet is concerned. Trolls, and those who tolerate them, are the curse of web-based information-sharing.




13:30



"But I don’t see how with 3D statues, bodies and whatnot, we are not facing the well-understood contact-wrap-around problem. What am I missing?"

Luigi  Garlaschelli had something to say on that score , and I'll try and find his exact words and insert them here later. For now, there are two main points that need to be made. First the TS image does not look like a photo of a 3D person in which one views the sides of the face or torso, limbs etc at an increasingly oblique angle. The TS image does not have sides, receding or otherwise.  It's essentially bas-relief in that respect, like the head or emblem on a coin, with just enough 3D relief to create a realistic effect, and then only after uploading to 3D-rendering software (ImageJ etc).

Secondly, the idea that imprinting off a fully 3D object or person must always produce a grotesque image with lateral distortion simply isn't true. That is only the case if one uses, say,  paint as one's imprinting medium, and makes a conscious effort to press the fabric around the sides to ensure image capture through a wide arc of circle.

But taking a thermal imprint is not the same as creating one in paint if the heated template is pressed down into linen. Why not? First, considerable force is needed to get appreciable penetration into the linen if there's an underlay (say a damp cloth) offering resistance to penetration. So the end result may look as if it had been taken from a bas-relief - because much of the 'side relief' has escaped being imprinted.

There's another factor. Even if the linen did make contact with the 'side relief' it may receive little heat because of the angle of presentation. Thermal imprinting requires heat transfer which in turns requires contact pressure acting at or close to the geometrical normal. Pressure is less important if one is using a "sticky" substance like paint on which so much of the "lateral distortion" notion appears to be based.

Here are thermal imprints obtained by pressing a heated brass crucifix into linen, placed over a damp underlay, either standard  conditions (no flour) or the new system (a thin layer of flour brushed over the surface), Ignore the water stains coming up from the underlay - except that they serve as a marker for impact pressure


Where's the lateral distortion in either picture? If it's there, it's very slight.

 Those two imprintings have since been thoroughly rinsed in warm water, and are presently hanging out to dry, to compare the water-resistance of the two images.

While waiting for that result, here are the above images after 3D rendering (ImageJ).

 Note the TS-like 3D appearance of an imprint off a 3D 'subject'. So why all the current preoccupation with the notion of the TS image having been "painted"?  When did we last see a painting with no 3D history respond so magniificently to 3D-rendering? In any case, where's the evidence for a classical artists' pigment?  Walter McCrone pursued an iron oxide will o' the wisp,  and ended up in a microscopist's mire of his own making.  STURP found none, and instead found a reflectance spectrum that matched that of "dehydrated, oxidised, conjugated (don't-call-it-a-scorch) linen carbohydrate. 

The easiest way to create a negative image, if that was the intention, maybe to simulate a Veil of Veronica type 'sweat imprint',  is to imprint off a shallow bas relief template. All one has then to do is to choose one's imprinting medium. Pigment? Chemical etching of linen? Simple contact scorching? Invisible ink (lemon juice or milk effect)?  The possibilities are endless. I've just added another to the list of candidates - plain white flour. What's more, it's been tested  and so far not been found wanting. But these are early days. Maybe not as early as 30 AD, but mid-1300s looks a better bet. I raise my hat to the medieval artisan who pulled off the greatest marketing coup in all of history against some keen competition (don't ask).

And here are those same two images after repeated washing and wringing out in warm water:

 Both images have survived having the excess unreacted flour washed out.
It's not that I imagined that water-resistance was a prerequisite for the TS image itself (while recognizing it has been exposed to water). It was more a case of wanting to be sure that there was not a layer of unreacted starch between image and linen that might have degraded and/or lifted off over the centuries, taking the image with it. The water test suggests that the image is in close contact with and firmly bonded to the linen.

Here's the same picture (immediately above) after 3D rendering.

Might it be said that the flour image is the more subtle of the two, if only that more of the heat-induced pigment (Maillard) has been washed out?

There are some interesting correspondences too between the regions of highest image density and those on the Halta Definizione image (BBC site) after image-enhancement, notably the head and shoulder blades. That may be pure coincidence, needless to say. Again, it has to be repeated, where's the lateral distortion?

 Addendum Thursday 30 October

Earlier I expressed surprise at being unable to see an 'elevated' nose in a colour-coded 3D rendering of the Halta Definizione image,  i.e. in ImageJ's Thermal LookUp Table mode. That was a clear embarrasment where one's model of imprinting off a 3D template is concerned, though there's a possible 'out',  admittedly not terrible convincing, by supposing a very shallow bas relief was used with a pancake-like nose.

No need for consternation and alarm. I've just run through the Thermal LUT imaging again, upping the min value control (lower right) in small increments.

All settings the same except the "min" value, lower right hand corner, which was gradually increased from left to right to stretch/amplify the vertical relief (see colour-coding bars). All were done on the "as is" Halta image off the BBC site.

 The nose IS there showing high relief, but it only shows well over a fairly narrow range of min values (60-73%) and even then is somewhat blade-like at most settings. Here's a close up of the third graphic in the above series which arguably shows the nose to best advantage as being at least comparable to other high-relief features.

Yes, the nose IS quite definitely there. How did I manage to miss it first time round?

Phew. For one moment I thought we were in trouble (especially in view of all the current Shroudie chatter about the image having been painted on, the pigment having since conveniently flaked off - every last bit of it - to leave just a faint cast or shadow of its former self. Yeah, right).

I personally prefer STURP's interpretation (my bolding):

No pigments, paints, dyes or stains have been found on the fibrils. X-ray, fluorescence and microchemistry on the fibrils preclude the possibility of paint being used as a method for creating the image. Ultra Violet and infrared evaluation confirm these studies. Computer image enhancement and analysis by a device known as a VP-8 image analyzer show that the image has unique, three-dimensional information encoded in it. 

                                       (Chunk of text omitted here in interests of brevity)

The scientific consensus is that the image was produced by something which resulted in oxidation, dehydration and conjugation of the polysaccharide structure of the microfibrils of the linen itself. Such changes can be duplicated in the laboratory by certain chemical and physical processes. A similar type of change in linen can be obtained by sulfuric acid or heat. However, there are no chemical or physical methods known which can account for the totality of the image, nor can any combination of physical, chemical, biological or medical circumstances explain the image adequately.

                                                        STURP 1981

Pity STURP and others missed the two-tone image.  Had they not done so the possibility could have been entertained of there being image not only on the linen fibres per se, but on an additional impurity coating, maybe Rogers' starch and saponins (though I doubt it) or alternatively on some additional material capable of producing its own red-brown coloration, one for which my plain white flour serves provisionally as a model. See the quotation at the top of this posting.


Thursday 10:36

Oops. Have just realized the source of my error as regards interpreting the two-tone image.



I interpreted the rose-coloured regions as being those with the highest relief (chin, cheekbones, brow ridge etc on the face, and the chest, shoulder blades etc on the frontal and dorsal sides). That's why I was at a loss to  fathom why the nose was not also rose-coloured, but we know it's high relief.

Scales have suddenly fallen from eyes. It's NOT (just) relief that is responsible for the colour. It's something else. But what?

Might the flour model be giving us a clue?  It's not just the elevation (necessary but not sufficient). It's the FLATNESS of those areas. The nose does not work because while it's elevated it's not flat.

So why should an elevated flat region result in a different tone? Maybe an added powder (like my white flour model) sticks to it better.

Ring any bells? Luigi Garlaschelli used powder 'frottage'. Interestingly the powder was artist's ochre, i.e. red iron oxide, Fe2O3.  Now I'm sure if the rose -coloured regions above were iron oxide, then we would know about it, given the focus that Walter McCrone had on iron oxide too in trying to prove the TS image had been painted on.

So where does that leave us? My initial hypothesis still stands - that we are looking not only at scorched linen fibres but an additional Maillard product from a thermal interaction between a reducing sugar and protein (or some other source of amino groups). But we now have to consider other possibilities that do not necessarily involve any chemical reaction at all, but simple adhesion of a fine powder to elevated flat regions, maybe with some thermal bonding too to explain why they don't all quickly drop off.

Thursday 13:20

So what about the real thing - the Turin Shroud?  Does it show any visual evidence, under the mciroscope, of having been coated with a powder of some kind?

Unfortunately i don't have access to an archive of photomicrographs, and the only person I know who does is Thibault (aka Thunderbolt ;-) Heimburger. He included some Mark Evans close-ups of image areas in the first of his 'anti-scorch' pdfs (there was a second selection too that came a while later which I am trying to track down).

Here's just one I found showing precisely what I predicted (though whether that's a fluke or not remains to be seen).

Look carefully at the regions o highest image density inside the yellow rectangles. See anything?

Here's the same with new settings (-11,100,1)

Am I not correct in thinking that there are dark specks associated with the tan-coloured areas, which are unlikely to be artefactual (chance deposits of dust etc) given they are absent for all intents and purposes in the less-strongly coloured non-image areas?

Flour particles, toasted?

I really must find those other Evans pictures, labelled according to anatomical region (nose etc) as I recall.

13:50  Have located the link to the pdf, which can be found on this shroudstory posting from about a year ago.

13:55: Yup, everywhere you look, you see those black specks on the image-bearing threads. They don't seem to be anything like as well represented on adjacent paler threads.

It's going to take a while to get all those images captured and cropped. I'll be adding them here on the end, having made a decision to stop putting up new postings (mentioned earlier) and concentrating instead on reinforcing the ones I've already posted with technical appendices etc etc.It's sufficient now that folk know my preferred model(s) and the general direction of my research. There is no need any longer to spoon-feed on a daily basis (and it takes the pressure off me not to feel I have to post - and then have to endure the guaranteed sneers and sniping from the anti-anti-authenticity brigade. Go boil your heads, you anti-anti-authenticity brigade.

14:40

Click to ENLARGE. Look for dark specks.

Click to ENLARGE. Keep looking

Click to ENLARGE etc

Click to ENLARGE etc

and now. last but one, here's one kind of control, which is not an image region but a scorched region from the 1532 fire.

Is it my imagination, or are we seeing far fewer appearances of those dark specks?

Just one more. (I'm keeping the fly in the ointment till last).

OK. So who said anything about it being a perfect world (this being the only picture I can find for "Clear cloth", which sadly is not clear enough of dark specks for my liking). But at least one of  the particles  looks distinctly blue, so can hardly be a toasted flour particle. I would say the general impression is that of a relatively clear,field  something one cannot say for the image-bearing regions where the dark specks seem more prominent. But they will say I am biased won't they ( which of course I am) ? But at least I admit that, and do not pretend to approach science with total objectivity. How can one do so if attached to a particular working model? The important thing is to have that working model , to make its presence visible in one's Discussion, such that folk can recognize and discern one's bias. One cannot hope to eliminate bias in science. One has to be content with recognizing it and containing it.

Working hypothesis. There are (or were, before the 2002 conservation measures, including that unforgivable hoovering) a scattering of dark-coloured particles on the TS concentrated mainly in the image-bearing regions, with far fewer in non-image regions.

An analysis of those particles would show them to be a substance that has been rendered yellow or brown by thermal energy ("heat" in common parlance). A possible candidate might be white flour particles  - an intentional additive - one that  acquired colour via a Maillard reaction, thus contributing to the image-forming process and  hence its heterogeneity and complexity.

19:25

As ever, more and more work beckons. First, one will need to do microscopy on the flour-coated  imprinted linen to see what happens to the appearance of individual flour particles, and whether or not they match the specks one sees in the above Mark Evans pictures, at least in terms of size.

Then comes the difficult part: to track down such papers are available online from the Walter McCrone Microscopy Institute on the studies he did on sticky-tape samples supplied by Ray Rogers. I definitely recall seeing one summary that had a long long list of the different types of particle he had identified.

One wonders what he would have made of those dark specks we see above if indeed they were flour or some other 'food' type particle that had undergone a Maillard reaction. One imagines it would take some fairly sophisticated kind of spectrographic microscopy  to make a positive identification, but that is not my area, so there's a steep learning curve that will need to be climbed to make headway.


Friday 31 October

Here, right on cue, is the NY-based legal beagle John Klotz, leading member of what I termed the 'anti-anti-authenticity' brigade:

John Klotz

October 31, 2014 at 5:35 am

Reply

It wold be nice if before he comments that Colin acquaint himself with the breadth of of the STURP study. Dark spot anomalies were discovered among on the the foot and kneww. They have been subsequently analysed as limestone consistent with limestone found in Jerusalem.
I recall that Berry’s expertise and career involved analysis of issues related to nutrition? If so, I would suggest that he get his head out of his …oven.
It would be nice if Colin has a sense of humor but he will probably have a snit about my analogy.

Forgive me if I leave the "science" such as it is to another day. I do not engage with trolls. The proof that John Klotz is a troll, not that any is needed,  is the routine label he likes to stick on us - viz. "pseudo-skeptics". The suggestion is that anyone who attempts to argue that the TS is of medieval provenance is covertly pushing some kind of hidden agenda to do with religion or ideology (and yes, an attack on HIS religion, HIS ideology).

This retired biochemist (who has worked in many areas of health, disease and biomedicine, nutrition being just one) had a long-standing interest in the TS going back to the late 70s ("Silent Witness" etc). It was re-awakened by headlines that appeared in UK newspapers some 3 years ago, which incidentally prompted the very first posting on this site - the reporting of new experimental phenomenon that I called "thermostencilling". (December 2011)

 An example of a headline ("The Independent", Dec 2011) that really stuck in this scientific craw was
this one (there were many more in a similar vein)

Don't you just love the bit about ""after years or work trying to replicate the colouring of the shroud..."? Published where, one might ask? Or even just mentioned in passing at which of many shroudie congresses?


No John Klotz and fellow ideologues  It's now't whatsoever to do with philosophy or theology or cosmology or your own peculiar mish-mash of quantum something or other. It's purely to do with science and its unique modus operandi, shamelessly bypassed I might add by those publicity-hungry so-called scientists at ENEA. (In the UK we would have described them as technologists, not scientists, based at any rate on abstracts of their published output).

 Technologists should leave science to the scientists -  but that's by the way and a personal view needless to say. Lawyers too should not presume to know what this scientist has or has not read - but I'll tell John Klotz this for nothing.  I have forgotten more about the properties of calcium carbonate in its different crystalline forms than he will ever know.

October 31 19:40

Here are my future report dates. They will be short no-frills summaries describing simply what was done, and what if any (firm) conclusions were arrived at.

If there were no firm conclusions, a statement to that effect will precede the report.

# Friday 14 November

# Friday 28 November

# Friday 12 December

# Tuesday 23 December

Dates in New Year to be announced.

Righty ho folks. Time now for a quieter life. That's me, the experimentalist, signing off now - reporting back in 2 weeks.   Slight change of plan (14th November): I'll continue to comment on science matters in general, including the TS - but cease "thinking aloud" in real time re my now private research.



Technical appendix

McDougalls Plain Flour:

Composition (per 100g)

Carbohydrate: 70.1 g

of which sugars: 1.4 g

Protein: 10.4g

Fat: 1.3g

of which saturates: 0.2g

Fibre: 3.2g

Sodium: trace

No information is given on the composition of the sugars, but I would expect them to be mainly glucose, maltose,  maltotriose etc, i.e. reducing sugars derived from starch amylolysis, rather than the non-reducing sucrose.

Modelling the Shroud of Turin image with a flour-assisted Maillard browning reaction.

The experiments I'm about to describe may turn out to be the most important of the scores I have done and reported here and elsewhere. There again, they may turn out to be totally irrelevant (it will probably need a STURP Mk2, courtesy of the Vatican and Turin custodians). But experimental modelling of the TS image has been my niche interest and activity, so to speak, making it important to get this posting not just scientifically-respectable, but readable and comprehensible to all visitors, whatever their level of scientific literacy. In other words, I'm going to keep this as simple as possible, albeit at the risk of it seeming light. For all I know, it is light, and must leave others to judge.

 Here's a summary of the experimental design.

Fig.1: Sprinkle plain white flour onto linen from a 'pepper pot' next to a straight edge.

Yes, that's ordinary plain white flour that's been sprinkled onto the linen, The purpose of the rule is to get a abrupt edge to the flour, across which a heated metal template will then be placed to produce a scorch imprint that is (a) with flour (b) without flour (control). One can just see the end of a brush in this cropped picture that will be used to spread the flour as evenly as possible.

Fig.2. Appearance after smoothing out the flour (with added contrast/brightness to highlight the flour).

Fig.3. Remove the straight edge. Now ready for the first imprinting, where a heated metal template will be applied so as to make contact with flour/non-flour zones simultaneously.

.

Fig.4. Heat up  metal templates on a ceramic hob (two near-identical aluminium sharpeners were used, labelled A and B for my own convenience).

.

Fig.5: Success! The flour greatly assists thermal imprinting of an image of the template. (Some distracting images from a previous experiment have been masked).

.

Fig 6:  The same experiment as above, but repeated 4 times. The template was applied twice in the first two pressings (labelled 1 and 2 above) and three times in the third and fourth pressing. Note again how the first pressing abstracts so much heat from the template as to render it less capable of producing a second or third imprint.

 Conclusion. The white flour performed exactly as predicted (see earlier, and BELOW)  making it possible to create a scorch imprint on linen at a lower temperature  than  needed to scorch uncoated linen.

 Why was the above result predicted? Here's a brief recap of the thinking that led to my doing what otherwise looks more like kitchen cookery than scientific experimentation.(One of my closest and dearest relations made little attempt to conceal displeasure at the perceived 'downmarket' direction this project had taken, coinciding with the appearance of McDougall's Plain White Flour!).


Yes. I'm pausing here to explain the background thinking that lead to the above experiment. There are more experiments to come - indeed in this same posting - but first I need to make sure that folk are aware of the rationale for the present series of experiments before ploughing on.

Rationale

It began many moons ago (Spring 2012 to be precise) with the hunch that the reported properties of the TS scorch fitted closely with those of a contact scorch, at least at the macroscopic level. Sure, there are unresolved questions about microscopic properties, but as I recently said elsewhere, I'm far from convinced that the so-called microscopic properties are real and/or significant if based, as appears to be the case, on nothing more than photomicrographs of TS fibre bundles, notably the (excellent) Mark Evans pictures, finally released from STERA's copyrighted image bank thanks to Thibault Heimburger MD).

It's one thing to say it's a scorch. But why would a medieval forger opt for that technology, given it requires an initial investment of time - and money- to get things right. Why not simply paint an image, as proposed by Charles Freeman?

Answer (speculative needless to say)?

The aim of the forger was to create an image that could be claimed to be have been left by the crucified Jesus immediately on being transferred from cross to Joseph of Arimathea's "fine" linen. It would have been an image imprinted in blood (obviously), but, less obviously in sweat as well. But from the very beginning of its recorded history, the TS image has been referred to as "sindone" (Latin) or suaire (French) which has connotations with sweat and sweat cloths (as in the Veronica Veil)..

So a medieval forger may have been looking for a means of simulating a "faux" sweat imprint. What's more, it would ideally need to be novel and sophisticated technology that would not be immediately be spotted as "old" technology and  instantly dismissed. In other words, there had to be an exotic, state-of-the-art aspect to the technology that would intrigue the first cohorts of relic-seeking pilgrims.


So what may have been exotic new technology in the 13th/14th century where making images are concerned?  That was the question this blogger was asking himself nigh on 3 years ago, and it did not take long to think of an answer (admittedly not terribly original or earthshaking) - namely INVISIBLE INK.  

I used to have a hobby book as a child, with a page devoted to invisible ink. One dipped a pen in either milk or lemon juice, and wrote a message on paper. One left the "ink" to dry to a near-invisible state. One then held the paper over a source of heat, and gradually the writing appeared, more brown than black, but aesthetics were not the object. All that mattered was that one could send and receive invisible messages that could be made visible merely by holding over a candle (1950s advice, now censored by H&S) or something that required no naked flame (a cooker bob etc).

Might linen, impregnated with lemon juice (maybe more hygienic than milk) serve as a better surface for imprinting from a heated template than plain untreated linen?

Result (October 2012) : a posting onto my specialist Shroud site entitled: "Refining a model: children's invisible writing trick with lemon juice allows thermal imprinting at a much reduced temperature."


It's one thing to propose a substance, available in medieval times, that might account for the TS image. One then has to define its chemical action with a view to matching up against the fine details of image characteristics. How might the lemon juice or similar have acted? Surface chemistry on the linen fibres, leaving the latter unchanged? Or some kind of chemical etching effect on the linen fibres?

It was at that point the project foundered. The literature on the 'invisible ink' effect was vague, with some claiming etching. others that no linen was required for production of dark pigments on cooling. I confirmed the latter by heating on glass.

Chemistry? Citric acid? Maybe some help from sugars too, notably the chemically-reactive ones like glucose?  Roadblock: I tested citric acid and glucose, singly and in combination, and observed no  acceleration of 'scorching' comparable to the one seen with lemon juice. There was also some unflattering comment on shroudstory.com about qualitative, non-quantitative experimentation (shrugged off,  but no positive incentive to probe and report on unexplored areas when one's scientific modus operandi  is called into question. Needless to say, qualitative experimentation has a vital role to play, as does quantitative, the two being complementary.).


Later, much later (years not months) there was a discussion about some kind of priming of linen and I reminded folk of the lemon juice finding. Someone expressed an interest. That was the cue go googling to see if I had missed anything re the mechanism of the effect. This time I turned up trumps. There was an account in a book of the non-enzymic browning of lemon juice, i.e.a Maillard reaction. While citric acid assisted, the chemistry depended mainly on the presence of ascorbic acid (Vitamin C).

Quote from the above passage: "It seems probable that threose is a major facor in Maillard reactions involving ascorbic acid".

So what is threose? It's something this biochemist has encountered rarely. It's a simple monosaccharide sugar that resembles glucose in its chemical structure, having a potential aldehyde group that endows it with reducing properties, but has only 4 carbon atoms instead of 6. It's a tetrose, not hexose sugar.

Threose (D form - the L form from L-ascorbic acid is the mirror image). It exists in solution as an equilibrium between the open chain form (left) and the cyclized form (right). Note the terminal aldehyde (CHO) group which confers reducing properties and ability to produce Maillard reactions.

Threose reacts with free amino groups wherever it finds them to give a complex series of condensation and dehydration reactions that ends in polymerization to brown end products collectively known as Maillard products or melanoidins.

Enough of the detailed chemistry. Who would have thought that the intense scorches formed above with lemon-juice treated linen were Maillard reaction products (probably), not pyrolysed carbohydrates of linen, the latter involving carbohydrates only, sometimes oxygen, but no requirement for nitrogen.

It was then that inspiration struck. If one could sensitize linen to scorching by impregnating with the TWO component needed for a Maillard reaction - reducing sugar and amino groups - then why restrict the choice to liquid solutions (messy). Might one use a solid - especially one that was finely powdered, and one moreover that was easily available in medieval times?  Would WHITE FLOUR work?

Answer- YES!!!

What's especially interesting is that up till now, Maillard reactions have featured prominently in 'shroudie' thinking, due to the 'diffusion' model of STURP's Raymond N.Rogers.Based on microscopy of TS image fibres stripped off with his Mylar adhesive tape, he had claimed that the image resided on an impurity coating, not the linen fibres per se. The coating? He claimed, with scarcely any solid analytical evidence, that the linen had been coated back in Roman times with a layer of starch and/or soap-like plant saponins. He postulated that these polysaccharides had degraded spontaneously to reducing sugar, that then reacted with gaseous putrefaction amines  (putrescine, cadaverine, ammonia etc released by a decomposing corpse. the pros and cons of that hypothesis can be discussed another day (suffice it to say I personally cannot take the idea seriously, given the host of factors that would need simultaneously to be right, quite apart from unfavourable thermodynamics at ordinary environmental temperatures). But note the similarity (and differences) between Rogers' proposals and the one here. Rogers envisaged a starch coating that depended on the corpse to supply the amine needed for a Maillard reaction and a yellow or brown image, and a reaction at environmental temperature. Mine depends on applying a coating of flour (starch  and some pre-formed natural reducing sugars - glucose, maltose etc- AND proteins), which is heated by an applied meta template. The reducing sugars react with free amino groups present in side chains on the protein, notable the epsilon amino acids of lysine residues to form Maillard products.

Let's suppose that one has almost serendipitously stumbled on the principle by which the ghostly superficial looking Shroud image was engineered - intended to be seen as a sweat imprint. How would that Maillard reaction have been used in practice to produce an image from a template? What was the template - a metal effigy as assumed so far-  or might the technology have been adapted so as use a real person, living or dead, as the template?

What follows now is a brief description of follow-up experiments that were a little more adventurous, a little more ambitious, some might say over-ambitious (but they needed to be tried).

If the TS image had been 'faked' using a Maillard reaction in an applied coating, whether flour or something else, did it need to use a metal statue, or similar, which let's face it requires a sizeable investment of time and money. Might it have been possible to use the same chemistry but with a different technology such that no statue was needed. Indeed, thinking of Garlaschelli's powder "frottage" which used a real human being (student volunteer) might the same be possible using Maillard chemistry?

Why not indeed? Why not a two stage procedure, modelled in what follows, in which a metal template (which could be replaced later with one's hand) is first coated with a film of vegetable oil, then white flour (which should stick to the oil), and then pressed into linen to create a flour imprint. What happens if the imprinted linen is then baked in an oven with careful temperature control. Might the imprinted area be selectively scorched?

Let's start with a bas relief as template (while imagining it to be a 3D statue or even person):

All ready to go: brass template, olive oil, and a sealable polythene bag with plain white flour. First smear a thin film of oil onto the template, then place inside bag, then, gripping the edges of template with fingers (through the plastic) ensure it becomes evenly dusted with flour.

Flour-coated template, ready for first printing-by-contact

OK, not the most sophisticated way of heating the linen and its (faint) flour imprint, but I needed to have everything open for maintaining a second-by-second watch with camera ready.

Interesting! Shame about the grid (and I should maybe have knocked off that surplus flour that's left dark clumps of scorched flour and/or oil  here and there).

It's been over-roasted, obviously. That apart,  if  you look carefully, you can even see the template lettering. Shame it's reversed, as happens with contact printing.

So it's feasible in principle to create an imprint off a cold, unheated bas relief template, using the two step procedure above. But the roasting step could require very careful temperature control so as to get optimal differentiation between image and background. A little browning of the latter is not a disadvantage. Indeed Garlaschelli used oven-heating specifically to achieve a more aged look.

Now let's see how well the flour/Maillard system works with a fully 3D template.

For that, I used the brass crucifix (above) purchased off a stall in Antibes' open-air market in the Place Nationale.

First, here's a reminder of what one sees when the crucifix is heated and pressed into plain linen, no flour.

Crucifix smeared with oil, then coated with flour, as described earlier

Here's the flour/oil imprint before roasting.

Oh dear. Could do better. Like using gentle heat, over a longer period of time. Notice to fellow blogmeisters. Please do not display this photo as representative of the new technique. The only reason for displaying it now is archival: it  shows what can go wrong when one's in a hurry, using a modern electric hob with excessive rate of temperature rise. What's needed now is use of an oven with more stable temperature environment, albeit less handy for keeping tabs on progress and taking photographs.

Supplementary experiments (of secondary importance - for specialists only)


One would predict that plain starch, free of protein, would fail to give the thermal sensitization seen with white flour. The closest I could find in the local shops to plain starch was maize corn starch (misleadingly called maize flour in the UK, but clearly a washed starch, given the low protein analysis on the pack).

Corn starch spread evenly against straight edge as above

First test:  ????

At first glance, it looks embarrassing for the Maillard hypothesis. Maybe it is. Why is there such a big contrast between starch v control on the first impression, if protein is needed, which starch lacks?  But note the way the difference between starch v control falls off rapidly with the second, third and fourth imprint from the cooling template. Maybe it's only at the highest temperature that the starch pyrolyses with no need for protein, no need for a Maillard reaction.  (The grey coloration from the later pressings is due to water coming through from the underlay - evidence that I was pressing hard in an attempt to elicit an imprint).

Second test: ????

This a repeat of the above, with a re-heated template, see 5th image, but showing the same rapid fall-off (6th and 7th).

Reminder to self:  Forget about untreated linen controls for now: do an edge-to-edge comparison of wheat flour versus corn starch. Prediction: the first will always scorch more intensely at any given temperature than the second. Working hypothesis: Maillard reactions  to give browning occur at lower temperature than pyrolysis of linen carbohydrates.

+++++++++++++++++++++++++++++++++++++++++++++

There were two other secondary issues that needed to be addressed:


1. Was the flour-assisted image entirely on the flour, or did it imprint on the linen as well. If the former, would it wash off?

2.   Is the oil entirely necessary to stick flour to template? Can the oil be dispensed with?



Dealing briefly with the first: "How firmly is that 'toasted flour' attached to the cloth? All I can say for now is that some test strips were placed in (a) tap water and (b) soapy water overnight, and had not noticeably dissolved in either liquid.

Update: the same was true two weeks later. The flour-assisted image is firmly attached to the linen. Quite how is a matter for speculation.




Stopped here 07:50, 19Jan 2015. More to come later today.  Ignore what follows.



Might this simple technology have been used by a medieval artisan as the chemical basis for producing the image on the Turin Shroud? Answering that question may involve a great deal of further experimentation (on the TS as well as in model systems), but as the man said: "The longest journey begins with a single step".

Next question: how easy or how difficult is it to adapt the above technology for producing a negative imprint on linen (recalling that the TS image shows light/dark reversal as first shown by Secondo Pia in 1898)? Does the linen itself have to be pre-coated, or can one attach the flour directly to a template? The latter note does NOT have to be heated. Maybe the coated linen can be heated after imprinting first with flour. I shall continue for now to deploy a metal template (unheated), but note that there is no longer any reason for using metal. Any object with  a modicum of 3D surface relief could be used to leave its negative imprint on linen, at least in principle - including, dare one suggest, a cooperative human volunteer, as in those magnificent Garlaschelli studies.

To keep things simple (initially) a  shallow bas relief  horse brass was deployed in the next experiment (but one could imagine it being a live human being as well, assuming he or she were willing to submit to the messy  but otherwise low-biohazard procedure about to be described).




Update Saturday pm

Have just used a fan oven set at 240 degrees Celsius and obtained this result with the new 'flour fingerprint' technology.

It's an acceptable image in gross terms, would you not agree? There's just one snag. It was powdery and easily brushed off. So there's a difference between roasting over a hot plate and roasting in a fan oven. Why that should be is something that is not immediately obvious. Or maybe there was some other difference, e.g. in amount of vegetable oil. Either way, it's good to see an image which (though I say it myself) might be said to occupy the Goldilocks zone (neither too sharp, nor too fuzzy). There is still so much to do. Maybe I should advertise for a lab technician, one who is prepared to evacuate the 'laboratory' whenever the General Manageress makes her entrance some 3 times per day.

PS:  It was even possible to get a second imprint off the same horse brass without needing to recoat with oil and flour, though the quality was needless to say somewhat inferior (and still brushed off).

It's only mentioned here since it demonstrates what might be termed the robustness of the imprinting technology.

(

The image from that crucifix, obtained with a Maillard reaction that did NOT require pressing hot metal into linen, was a bit disappointing, but then it was the first trial of the new technology. A better result was obtained using a bas-relief metal template, i.e. a horse brass with King George VI.

This is simply to flag up the new direction my research has taken, prompted by the discovery that the Shroud image is in fact two-tone (see posting that immediately precedes this one). While speculative, it is possible that the image is a composite of an intense  orange-brown scorch on linen fibres per se, with a wider more diffuse image that represents something else, possibly a Maillard product on something that had been added to the linen as a surface coating.
Takeaway message: the initial hunch was confirmed, namely that flour does indeed contain all the ingredients for an in situ Maillard browning reaction:  flour dusted onto the surface fibres of linen should, and indeed does, act as a heat-sensitizing agent. The beauty of flour, needless to say,  being a finely particulate solid, is that it does not soak through as would a solution to the opposite side to give an image there as well, except possibly a ghost image due to migration of a few particles through the interstices of the weave. ( See "Shroud second face". Possible explanation?)