The chemical principles behind the iconic Turin Shroud can now be explained. All that remains is to produce a look-alike copy.

Important update (13 May): for a 16 point summary of the new nitric acid model, see the new posting on my specialist Shroud site.

 

It's said that a picture is worth a thousand words. Here's a flour/egg yolk imprint done just two hours ago, photographed here after removal from the nitric acid bath, neutralized with bicarbonate, rinsed with water, shown here drying on the radiator, ready for processing in Image J (tone reversal as per Secondo Pia followed by 3D rendering).

Here's the above after further processing (click to enlarge).  Top left: the dried image after ironing flat. Bottom left: conversion to B/W, then a Secondo Pia style tone-reversal. Right: the secondary B/W image after 3D rendering (Image J).

It's taken over 3 years of almost non-stop experimentation, but this blogger/retired science bod is now able to explain how the faint negative image of the Turin Shroud was obtained (as a feat of medieval technology, aided by alchemists).

The task: produce a contact image that could be claimed to be that left by the crucified Jesus on Joseph of Arimathea's 'fine linen'.

It's incredibly simple in principle (why didn't I think of it sooner?):

1. Paint an adult human male (alive or dead) with an organic paste or slurry as imprinting medium (in other words, turn them into a giant rubber stamp). My preferred medium right now is a dispersion of white flour in cold water, but that could change).

2. Press linen against the subject (or subject against linen) to leave a moist imprint. Dry.

3. Develop the image chemically using a suitable reagent , one that converts the organic material to tan (yellow-brown) oxidation products (less probably Maillard reaction products).

My preferred reagent right now is nitric acid vapour, the means of production were known to medieval alchemists (notable "Pseudo-Geber" who may have been one and the same as an obscure Franciscan monk known as 'Paul of Taranto'

4. The yellow-brown aka sepia  imprint will be a 'negative' of the subject, inasmuch as the light/dark tones one sees in photograph are reversed. In other words, the highest relief  (nose, chin, forehead etc) will be dark, not light, and the lowest relief (eye hollows etc) will be light, not dark. They are light in a photograph as a result of reflecting most light. In an imprint, they are darkest through making best contact with a surface.

So I maintain that the plausible science is established - at least in principle-  so far as producing a negative  sepia 2D image from imprinting off a 3D subject is concerned.  Whether it matches all the additional or peculiar characteristics of the TS image (extreme superficiality, lack of reverse side image, lack of uv fluorescence, microscopic characteristics etc.) remains to be seen. However, let's insert a note of caution: not all those listed characteristics were necessarily there immediately after image formation, regardless of age - centuries or millennia. Some of those characteristics may be a result of ageing. At present it seems sensible to adopt a broad-brush approach, attempting to accommodate  only those 'headline' characteristics of the TS that have led to its being described as iconic or enigmatic. Where the latter are concerned, the prize for the most 'iconic' must surely go to the pioneering 1898 photography by Secondo Pia, which converted the Shroud negative back into a positive (by innocently treating the TS as a positive and convereting to a negative!).

It is the conversion one sees above that led to what must surely be the sound conclusion that that the TS negative image must be an imprint, probably a contact-imprint, one that on tone reversal allows one to see the 'real life' (or death!) appearance of the imprinted subject. It's for this reason alone that the dismissal by Charles Freeman of the TS as 'just another medieval painting' that has simply (and conveniently) lost its pigment over the centuries is so hopelessly blind to the implications of the negative image and Secondo Pia's spectacular discovery.

It's not sufficient, needless to say, to establish a scientific framework. There has to be a sizeable input of technology too. While history provided one or two pointers to the likely science (alchemy etc) there is no such  assistance where attempts are made to deduce the technology employed, i.e. applying the science in the manner that achieves the best end result. One does not even know for certain what the desired end-result was, or for what purpose, though I've believed it to be an attempt to simulate an ancient sweat imprint, ever since spotting that Veil of Veronica-like motif labelled SUAIRE on the Machy Mould for a Mark 2 (or Mark 1) Lirey Pilgrim's badge.  (It was that discovery more than anything that decided this researcher to abandon the idea that the TS was a thermal scorch, designed perhaps to symbolize the slow-roasting of the Templar leaders in 1314 for alleged heresy and other indiscretions. That seemed plausible given that one Geoffroi de Charney died alongside Jacques de Molay (Grand Master), de Charney being thought by genealogist Noel Currer-Briggs to have been uncle to his near-namesake, Geoffroi de Charny, Lord of Lirey, first recorded owner of the Shroud in western Europe).

So the working hypothesis IS that the TS is a simulated sweat imprint, that an imprinting procedure using an organic material was devised, probably with input from an alchemist, to develop the imprint chemically so as to produce a more intense, more easily visible yellow or yellow-brown colour. What we see now may of course be a pale shadow of the original, given centuries of fading, image fibre attrition etc.  But there's an upside to that: one does not need to be too concerned about one's pilot techniques producing images more prominent and/or well-defined than those on the Shroud.

After preliminary and somewhat unsatisfactory attempts to image from first  my hand (reasonable result) and then my own face (the less said the better - see preceding posting) I decided to use up-and-over imaging of the toes on one foot. The scale is handy for the size of my jars with the wide necks and ground-glass stoppers for nitric acid vapour. One can compare LUWU and LOTTO imprinting in the same experiment (which may or may not be relevant to the imprinting of the real Shroud). LUWU = Linen Underneath With Underlay; LOTTO = Linen On TOP, With Overlay).

I'll conclude this verbiage with photographs of results with this new tootsie test system as they come. Here's are some photographed just an hour or so ago. More will follow later. There are no plans to write any new postings until the current round of technology-testing is complete. Whole face imaging has been shelved for now. (Maybe Luigi Garlaschelli was right - a bas relief was needed for the face).

Imprint of toes onto linen (left) versus cotton (right). Imprinting medium: white flour/cold water only.

As above, after use of autocorrect in MS Office Picture Manager.

The lower half is a classical "footprint" obtained using LUWU configuration. The upper half is an imprint of the tops of toes obtained by turning the linen up and over, and gently pressing (LOTTO configuration).

More pictures to come (testing of egg tempera as imprinting medium etc).

Yes, egg tempera was the vehicle used as vehicle for paint pigments in medieval  times before the appearance of oil paint in the Renaissance. Despite being primarily egg yolk egg tempera not only attaches well to surfaces but is surprisingly durable. If searching blind for technology that might have been used to add flesh, so to speak, to the fundamental science, it would be unwise to ignore so common a commodity as tempera. In fact, there's one compelling reason for thinking why it may have been used, if only as part of a mix of ingredients: if the aim was to simulate a sweat imprint, it helps to have a visible yellow imprint before the chemical development (or indeed as a Mark 1 undeveloped imprint) given its yellow colour.

Here's the result of imprinting onto linen with a mix of flour, egg yolk and a little milk as extender.

...

Here's a comparison of three imprinting media:left- flour ; centre: egg yolk; right: flour + egg yolk. All had a little extra milk as extender (having been added to egg yolk to bump up the volume I decided the others should have it too).


Note the poor imprint on this occasion from flour "only". Well, as stated, is wasn't flour only. It was flour with a little milk. An immediate difference was noted compared with flour without milk - there was much less adhesion to the skin, much less force needed to pull the linen away from the skin.

The adhesion effect has been commented on earlier, with the observation that adhesion helps produce an instant high-fidelity imprint. That's due to the amazing ability of flour paste or slurry to stick onto so many different surfaces (this blogger has a photo album he made as a small child in which flour was used as an austerity-era paste - most  of the photos are still where they were stuck). A reasonable working hypothesis might be that milk has weakened the adhesive power of the flour. Good or bad thing? At first sight bad, because it means less flour attaches to the linen (probably) giving a weaker imprint. But might there be an upside? Possibly, as will be discussed shortly.

Yes, one encounters something quite unexpected when imprinting with flour paste. The linen quickly absorbs the liquid when pressed against the skin, such that the latter seems almost dry when the linen is peeled off. That makes for a good imprint, obviously, with so much flour transferred from skin to linen. But there's a possible downside. If transfer is complete, or nearly so at all contact sites, regardless of applied pressure, angle of contact etc, then how can the image be expected to show the 3D properties of the TS image. For 3D properties there needs to be some systematic factor at work such that variations in relief (height above a reference plane obviously, but maybe more subtle factors too) are captured in an analogue process to give variations in image intensity and subsequent 'apparent 3D' properties. That cannot happen if the medium transfer is too efficient at all points. So it may be necessary to include an additive, one that our medieval artisan might have included if only to make the adhesion weaker (he would not have been worrying about final 3D properties!).

Reverse-side imaging?  Yes, there's some at present, as the next pictures will show. But a medieval forger would probably not have wanted it either, if it gave the slightest clues to how an image was faked. This is where technology as distinct from science needs to be harnessed: finding simple ways of reducing or eliminating reverse-side imaging in the proposed flour/water model.

Here are some thoughts for a model system that focuses specifically on  efficacy of medium transfer as a function of 3D relief:

I would use the knuckles of my clenched fist as the 3D subject I'd paint the knuckles with various imprinting media (flour +/- milk +/- egg yolk etc) that had been coloured up with some ink or pigment, then press into fabric (probably re-using linen from previous experiments). The aim would be to find  a mix where the knuckles were imprinted more prominently than the rest of the fist, through having the highest relief. It would probably need to be a stiffish mix, whatever the ingredients, so as to avoid the mix being squeezed off the extremity down into the furrows between knuckles - not what one wants when trying to capture 3D relief!

Update Thursday 19:14

The footprint (mine!) top left was imprinted onto linen using a mix of white flour, egg tempera and a little milk. The image has been tone-reversed in ImageJ (bottom left).  The latter has then be 3D rendered (right).

The initial imaging was performed by standing on one foot, with a view to getting the best impression, but that was maybe not a good idea in retrospect: pressure would have forced the imprinting medium off the highest relief, eg the flat of the toes, resulting in less-than-satisfactory 3D-imaging.

Friday May 8

Here's the result of my fist-imprinting experiment. The result was disappointing, as will be seen, probably through an inappropriate choice of imprinting configuration (LUWU instead of LOTTO) that will not be repeated.  Iwill show it, however, and for 2 reasons. First, this is a real-time account of a research project, warts 'n' all. Second, as is so often the case in reseacrh, while an experiment may fail in its primary purpose, it can lead to unexpected and interesting side-observations. There was not just one, but two of those in the "Fist 1" so I'll now provide an, er, blow-by-blow account.

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Here's the consistency of the highest of 5 concentrations of flour/water dispersion tested.

Paint fist.

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Press fist into strip of linen, starting at the far left.


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Here's the imprint on the linen.


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Now add a measured volume of water to the flour/water mix with stirring to make it less viscous.



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Now repaint the fist with the runnier mix.

Repeat the process of diluting and re-imprinting 3 more times, working left to right along the strip.

Here's the final strip, with its 5 scarcely visible flour imprints. They will first be left to dry on radiator, and the linen then sewn to make a flat hoop, imprint on outside, to be suspended in nitric acid vapour over conc. nitric acid solution.

Here's the strip inside the 'developing tank', with a glass plate over the top. The clothes pegs were intended to keep the linen clear of the liquid acid.

In fact, one single linen thread had dangled down into the acid, drawing the latter up by capillary action.  A quick rep-adjustment put a stop to that, but the instant image development in the wet area gave an idea for another experiment, results of which will follow this one. The idea: to compare nitric acid vapour versus liquid solution as a developing agent.

Here was the linen after image development in nitric acid vapour, with the 5 fist imprints going from left to right.

Here's the same, with added yellow lines to act as dividers.

And here's the reverse side of the linen, with very little 'reverse-side image' - confirming that flour/water is a good imprinting medium in principle, despite there being much R&D still needed to produce a TS-like image.

Discussion

While the method works reasonably well for flat(tish)parts of the anatomy (see earlier results with the back of my hand, sole of foot) it does not like complex relief (face, clenched fist).

So those imprints above of my clenched fist are maybe difficult to recognize as such. But as hinted at earlier, it was a mistake  to have adopted the LUWU mode of imprinting. I had thought that passive pressure would give the simplest most recognizable imprint, but that was not to be, probably due to the right-angle turn at the knuckles , but other factors too, like excessive give in the underlay, and a possible rocking action. Never mind: the experiment yielded useful data in other respects as regards the possibility of using solution as a fast-acting alternative to vapour, and the virtual absence of reverse-side imaging.

The experiment also got me thinking about engineering the 'ideal' imprinting medium likely to yield the best 3D result.

The ideal mix will probably still flour as a major ingredient (large intact endosperm cells help reduce penetration and reverse-side imaging).  It will perhaps have egg tempera too, if only for its yellow colour, making it easy to know where to paint blood stains on top of body image. But it has (probably) to be paint-like in consistency and covering power, attaching first to skin, whether unwashed, with skin oils present, or washed (leaving unobstructed keratin, i.e. protein), but then transferring cleanly onto linen. There is now work to be done in identifying that mix, while at the same time maintaining credibility re the options that would have been considered in a medieval workshop.

Comparing nitric acid vapour and liquid solution as image developing agents

I reverted to LOTTO mode for this test. First paint back of hand with flour slurry (no additives).

Here again is that amazing 'cling film look one gets when placing linen on top, then pressing gently.

Here's the negative imprint - scarcely visible.

Now turn the imprint into a simple jigsaw puzzle. 2 pieces will developed in HNO3 vapour, two in conc HNO3 solution (70%).

Here I am adding the acid to one of those two pieces. Image development is seen almost immediately.

Here we are a few minutes later, with image development without noticeable leaching of colour, or migration from image to non-image areas. Success!

Here's the downside of using solution. There's a lot more acid that has to be neutralized before the linen can be removed for drying, ironing and photography.

here are the 4 developed pieces re-assembled. The image of the back of my hand is complete. There seems to be no reasons for thinking that vapour is superior to solution or vice-versa, at least where image-development is concerned.

And as before, there is scarcely any reverse-side coloration.

Next question: does one need concentrated nitric acid for development, if used as liquid? Might a lower concentration work too, albeit more slowly, but without the same degree of hazard?

Some quickie tests are in order, making serial dilutions of the conc acid, e.g. 70%, 35%, 17.5%, 8.75%  for a quick idea.

Come to think of it, use of nitric acid solution raises new technological possibilities. Let's suppose that the essential ingredient of the imprinting medium - provisionally white flour - is fixed instantly to the linen. But suppose there were additives in the medium that gave it a more functional paint-like consistency that were undesirable as left-overs in the final image. What is they were not fixed by the acid?  Maybe they could leach out into the liquid acid (not possible if vapour used), so that one was left with the just the chemical constituents needed for the 'right' kind of image.

Results: testing nitric acid solution as  developer, with a range of concentrations:

First, a paintbrush loaded with white flour dispersion was used to make a trellis pattern on linen. After drying squares were cut out for immersion in different concentrations of nitric acid solution.

Here are the squares in pots with the indicated concentrations of nitric acid (w/v). This was after about 30 minutes of contact. Pronounced orange colour has developed not only at the top concentration (70%), but at half that (35%) and half that again (17.5%). Only at the lowest concentration tested (8.75%) was there no unequivocal colour development.

Here are the same samples after 1 hour in acid, neutralization with sodium bicarbonate and partial drying on a towel.

Conclusion: the model works with nitric acid solution as well as vapour. What's more it's not necessary to use concentrated nitric acid (gives off fumes, hazardous).  It works well (and fast) with nitric acid diluted with water to 4 times its initial volume, i.e. to 8.75%, which  at approx. 2.75M is only a little higher than the concentration of bench dilute nitric acid (generally 2M).

Imaging of forefinger using the new quickie liquid developer (nitric acid SOLUTION) to compare different imprinting media.

Here's the final 3d-rendered image (posted first to allow transfer to shroudstory as progress updateI.

The stages in obtaining that image will be added later.

May 8, 19:12

The above 3D image was obtained while the test linen was still wet and drying on the radiator. (Man in a hurry).

The sample has now fdired and been pressed with a steam iron. Here are the definitive pictures:

The as-is imprints, after development in nitric acid solution.

As above, after tone reversal in ImageJ.  (A Secondo Pia transformation of a negative imprint back to a positive - or at least a pseudo-positive).

 
As above, after 3D rendering in ImageJ.

Now, back to the start:

Ready to start imprinting: flour slurry in the pie pot, egg yolk in the glass, and a 50/50 mix of the two in the egg cup.

After imprinting, drying on a radiator before chemical development. Note however the almost photograph like character of the egg yolk imprints, especially on the left. There's absolutely no reason why medieval folk should not have seen that kind of realistic imprint, albeit as a negative image. All that was need to produce trhe TS was to think up a way of fixing that egg yolk (or similar) image to make it permanent, maybe with some colour reinforcement.

And here's the new simplified image development step - simply immersing in nitric acid solution, 10% w/v and upwards. The lower end of the range is recommended to reduce fumes.

Update Saturday May 9

Feedback from Dan Porter's shroud story site (from Thibault Heimburger MD) and my response:

Thibault HEIMBURGER

May 8, 2015 at 4:52 pm

Reply

I have to admit that Colin’s work is very interesting.
In fact, it is the best work (still in progress) I ever seen, based on the “chemical imprint” hypothesis.
The fact is that the TS image is an “imprint”, not a paint, is obvious.
The fact that the TS image is a contact-only imprint rather than a contact+non-contact imprint is still undecidable.
Hopefully, at the end, we will see if the best contact-only hypothesis (the “chemical imprint”) can match or not at least the macro properties of the TS image.
Colin wrote (see his blog): “The task: produce a contact image that could be claimed to be that left by the crucified Jesus on Joseph of Arimathea’s ‘fine linen’.
Not only that.
The TS IS such an image. But this image has some fundamental properties.
So, we will see.
Sincerely, good luck.

Colin Berry

May 9, 2015 at 12:07 am

Thanks Thibault. Your comment is most gratifying, and shows true generosity of spirit, given our differences in the past.
In an earlier comment here yesterday, I was deliberating on what should be the ideal consistency of the imprinting medium in order to achieve best 3D effects. I said it should be paint-like, i.e. tacky and viscous, so as to stay where applied on the 3D subject, since if runny, it would flow off the highest points of the relief down into the hollows and mess up the 3D rendering.
Oops. I was forgetting that gravity can be made to work for one. If you want a liquid imprinting medium to stay put on the highest relief, and indeed concentrate at the highest points, then turn the subject (or template) upside down before imprinting, and press it DOWN into linen.
There are two types of subject-to-linen presentation one can use when imprinting, what I have previously called LUWU (Linen Underneath, With Underlay) and LOTTO (Linen On Top, Then Overlay).
Use the LUWU configuration(even if easier said that done where real people are concerned). That requires painting the subject with imprinting material, then lying face DOWN into the linen to imprint the FRONTAL surface. If the medium is fairly runny and mobile, then in the brief time the subject positions himself face DOWN, the medium runs to the LOWEST points of the relief, due to gravity, which would have been the HIGHEST points when face up. It is the concentration of medium at the new lowest relief that might generate most if not all of the negative and 3D properties of the final 2D imprint.
OK, so it might be tricky to get a clean imprint via LUWU. However, the purpose in hinting at a gravity-aided model is not to suggest this was how imprinting was actually achieved, but simply to flag up the wealth of options on offer. Yes, one risks attracting unflattering references to Occam’s Razor. But having a range of options for modelling is not the same as needing to attach a host of qualifying assumptions to a model through having a limited range of options.

Further update Saturday May 9

Have just this minute taken a picture of the latest experiment in progress (imprinting off a plastic 'Galaxy Warrior" from Poundland), and inserted it as opening graphic (with a cut-and-paste to shroudstory which has just done an agreeable and benign cover on this posting).


Here's the same image after drying and pressing briefly with an electric iron:

Yes, as I said in the caption, the two heads - frontal v dorsal - should have been separated (a little) and the two images, frontal and dorsal, should have been perfectly aligned on the long axis.  As the sign used to say above the maintenance workshop at a student hall of residence I once stayed at: "The impossible we do immediately. Miracles take a little longer."

Update: 12May 2015

Here's a new result, hot from the press, correction, garage.

It's posted here first as a 'linkable' graphic. It will then be posted to Dan Porter's shroudstory site, so as to keep folk there in the picture. Where next? Maybe write a post on my  specialist shroud site that's been dormant since December last year, saying why I think this result is important. The colour you see in that pot with the handle, bottom left, may well be the one that is on the TS, albeit faded with time.

What's in the pot to give it that red-brown colour? It's the isolated gluten (the viscoelastic protein that is responsible for breadmaking dough) from wheat flour, washed free of its starch granules, then treated with nitric acid.  It's maybe a bit soon to be speculating on what is in wheat gluten protein to give so strong an orange colour with nitric acid (the so-called xanthoproteic test). My guess, for what it's worth, is the high tyrosine content of wheat gluten.  It readily nitrates with nitric acid to give the 'sepia' colour, as per TS.

The small glass dish on the right has the starch that was washed out of the wheat flour dough. It does NOT give the same red-brown colour, merely a faint yellow coloration, possibly, probably due to starch granule protein (friabilin etc, as discovered by my colleague Philip Greenwell at the previous FMBRA i.e. Flour Milling and Baking Research Association,   developer of the Chorleywood breadmaking process, now part of the Chipping Campden and Chorleywood Food Research Association. 

Posted to shroudstory:


 

Colin Berry

May 12, 2015 at 12:13 pm

Reply

It says “figured out, sort of maybe” in the title. Might I humbly suggest there’s a bit less “maybe” now.

That’s isolated wheat flour gluten in the bowl at the back. That’s a portion of it treated with nitric acid to get the sepia (red-brown) TS-like colour in the dish bottom left. That’s the flushed-out, then gravity-sedimented starch fraction in the glass dish on the right, also treated with nitric acid, with faint yellow coloration only.
Why should wheat gluten (the protein fraction) of flour produce a orange colour with nitric acid? Answer: it’s almost certainly due to its high content of the phenolic amino acid tyrosine that readily nitrates with nitric acid in the so-called xanthoproteic reaction (used as a test for proteins).
In other words, the TS sepia colour is NOT due to dehydrated, oxidized carbohydrates, as suggested in the STURP summary. It’s due to nitrated protein formed by secondary chemical development with nitric acid of a contact imprint made from a human subject (dead or alive) using a slurry of white flour as imprinting medium.

Modelling the Turin Shroud: my flour/nitric acid vapour model looks better and better with each passing day.

Here's a quickie progress report, so for now I'll simply post pictures with captions only. Profoundly deep and penetrating physicochemical insights and analysis, guaranteed (says he) to knock your socks off, can wait till later.

The previous posting reported the use of a cooked paste of white flour and water in the initial imprinting of my own hand. But  there are theoretical advantages in using a dispersion of raw, uncooked flour (intact endosperm cells, enclosing native starch granules,  bla bla, less risk of reverse side penetration and image, bla bla).

Fig. 1: OK, so here's that hand again, but this time it's been painted with a thin slurry of uncooked white flour and water. (I might experiment with additives later to get a more even coating, but if the procedure works without them, albeit sub-optimally, then it makes for a more credible model.

Fig.2: If I had to choose just one picture to illustrate the power of the new technique (at Stage 1 imprinting) this would be it. Look how well the linen moulds to the hand. It's almost as if it had been painted white, instead of being covered with fabric. Why?

Fig 3: Here's the same in a separate experiment. Amazing, yes? Even the surface veins, sinews and fingernails show up.

Fig 4: This picture too is amazing in its own way, except that the reason is not self -evident unless you do the experiment for yourself. When one goes to lift off the linen, one finds it is STUCK onto the hand, and that considerable force is needed to peel it off, and that one's hand at the end is almost bone dry, with flecks of dry flour here and there. In other words, flour slurry behaves like superglue when it meets linen. (I predicted that in the previous posting, but let's not bother with the reasons why, except to say that like attracts like in organic chemistry, which accounts for the phenomenon of surface ADHESION, a neglected factor that needs to be considered in imprinting by physical contact).

Fig 5: So much effort is needed to peel back the linen (at least with raw flour) that the fibres of the linen become pulled away from their threads to form a sort of fluffy fleece. One can just about make out adhering particles of flour in the picture above. Might the boosted  'fleece' have something to do with the subtlety of the TS image, its indistinct boundary between image and non-image areas?  Or the ease of detaching image fibres vis-a- vis non-image (see STURP's Raynond N.Rogers)? Maybe, maybe not, but the results so far underline the importance of doing open-ended experimentation that just once in a while can throw up effects that are largely unpredicted, yet may or conceivably might play a key role in understanding the 'iconic' or 'enigmatic' TS image.

Fig.6: We've now moved from Stage 1 (imprinting) to stage 2 (image development). The imprint of my hand has been folded into a compact bundle (with securing stitches of cotton thread) and suspended over a tank containing conc (70%) nitric acid. It's the vapour that develops the image (see previous posting). Yes, nitric acid was known in the 13th/14th century (see my earlier posting on the writings of Pseudo-Geber, probably one and the same as the Franciscan monk/alchemist Paul of Taranto)

Fig.7: Well, that was a most welcome result, showing that the raw wheat flour worked as well, if not better than the cooked flour, despite having an entirely different consistency (the raw dispersion was thin and milky, nothing like to the thick gooey paste from boiled flour).  Predictably, there was less reverse side penetration and imaging.

Fig.7: Here's the linen being steeped in sodium bicarbonate solution to neutralize the surplus of nitric acid vapour adhering to the linen. (On this occasion, the linen had not been noticeably weakened by overnight exposure to nitric acid vapour, as checkied later).

Fig.8: Although not obviously weakened, the linen had acquired a faint beige coloration ("aged look"?). That can be seen in this photograph, where it has been placed on top of the same untreated linen.

Fig.9: Yes, there is a faint reverse side image (unwelcome for modelling purposes, though whether it would be so obvious against a centuries-old ageing is a moot point). But beware artefacts: one is seeing it here  against the same white background. See my previous posting for the false impression that can be created by back-reflection of filtered/coloured light from white of light-coloured backgrounds. Reverse-side images should always be checked against matt black backgrounds that prevent back-reflection through the interstices of the weave.

Fig 10: Here's the topside image, viewed against a black background, after neutralizing acid, rinsing, drying, and ironing.

Fig 11: Here's the reverse side, against the same black background. There is scarcely any reverse side image. Might the traces be removable, e.g. with soap and water, while still leaving front side image?

Fig.12: I had earlier wondered whether the nitric acid step in the new procedure could be replaced by plain-old oven incubation.  The answer would appear to be no. Oven temperatures in the region of 200 degrees Celsius that turn the flour imprint into a yellow/brown image also have an excessive darkening effect on the linen itself.  (The test was done with a metal template loaded with flour slurry at decreasing solid/water ratio: imprints were nothing like the TS image, being scab-like, and vigorous brushing failed to 'soften' the images).

Fig 13: At this stage I decided to do some before-and-after tests on the hand image. Thus the vertical cut to divide it into two approximate halves.

Fig 14: it's maybe not easy to spot, but a length of sticky tape between labels A and B has been pressed onto the image/non-image areas, which was then stripped off and stuck onto a glass slide  for later microscopy. The triangular notches were to remind where the sticky tape had been applied.

Fig.15: That's the slide with sticky tape. Shame about the air bubbles, but one can see stripped-off linen fibres peeping out from the tape at the top. They don't look highly coloured (but then this a more subtle model system than contact scorching).

Fig. 16: We're now about to see how much of that flour/nitric acid image can be washed out with soap AND vigorous rubbing. Is the image simply adhering flour (nitric acid-modified) or are there grounds for thinking that the technique has also chemically modified and coloured the linen fibres per se?

Fig 17: Here we are an hour or so later. The quality of the photo is not that good, with the (artefactual?) vertical,banding that might have been a trick of the light. Nevertheless, if one looks closely one sees that the image has NOT been completely washed out with soap and vigorous rubbing. There is a faint yellow DIFFUSE image area, ie. my fingers, suggesting that the technique has resulted in coloration of linen fibres, despite using an external agent (white flour) to kick start the process of coloration.

Fig 18: Finally, when one turns the linen over, against the black background, there's scarcely any reverse side imaging.maybe not suprising given the particulate nature of the imprinting medium (whole endosperm cells of wheat flour that don't readily penetrate the weave, even from a thin dispersion).

However, the key finding of this exercise must surely be the way that the linen moulded itself to the contours of my hand, despite using a thin milky flour dispersion, so as to show up an amazing degree of detail. that has surely to be a big plus in any model that relies on contact-imprinting. That same capture of detail is then apparent in the final developed imprint. We seem to have a highly promising model here that challenges the pro-authenticity view that the TS image is too subtle to have been produced by conventional physics and chemistry. Never write off conventional physics and chemistry. The ability of molecules to interact and self-organize should NEVER be under-estimated. It's almost as if they have minds of their own (in a sense they do, given their quantized energy levels that became permanently imprinted at an early stage in the history oif the Universe (stellar nucleosynthesis).

Update:Monday May 4

I flagged up this posting yesterday on Dan Porter's  shroudstory site, currently celebrating its 3,000,000 views, with this comment:

Colin Berry

May 3, 2015 at 5:24 pm

Reply

Hello again folks. Have today found that the results with the new model can be obtained using a thin slurry of white flour with COLD water with a consistency intermediate between that of milk and single cream. Have today posted 18 new photos.
http://colinb-sciencebuzz.blogspot.co.uk/2015/05/modelling-turin-shroud-my-flournitric.html
While I had predicted earlier on theoretical grounds that native wheat endosperm cells, such as exist in uncooked white flour, would bond well to linen fibres (due to like-for-like attraction of primary cell walls of similar chemical composition) I never for a moment imagined just how well. Not only does the flour dispersion behave like an instant adhesive, bonding the linen to skin, but it also makes the linen conform closely to body relief:



Isn’t that amazing?
It then took a bit of effort tearing the linen away from my hand for Stage 2 development (nitric acid vapour, as before). Superficial linen fibres were broken in the process, creating a kind of fleece. Might a similar bonding at the imprinting stage have contributed to the ‘iconic’ nature of the TS image (i.e.fuzzy, ghostly quality) one wonders?
I’m thinking of doing a facial selfie using the new technology, but may have to cut the imprint into quarters for separate development, given the limited capacity of my developing tank (the size and shape of a goldfish bowl).

Here's the response from my friend DavidG (who seems uncharacteristically to be having an off day) and my reply:

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  David Goulet
  May 3, 2015 at 8:04 pm

  Reply

  Paper mache? I too am amazed at the result of your experiment but we aren’t looking for a 3 dimensional image model, just one that photographs that way. Or is this merely a stage which leads to that model later?

Colin Berry

May 3, 2015 at 11:20 pm

Reply

Oh dear. Methinks you need to visit my site, DavidG, and remind yourself of how the new (old?) technology works. ;-)
In brief: paint a portion of one’s own or someone else’s anatomy with a milky-white suspension of white wheat flour in water. Press the painted part of that anatomy into linen to leave a very faint, indeed near-invisible imprint. Leave the imprint to dry, then suspend the linen above conc. nitric acid taking all the necessary precautions (gloves, eye protection, face mask, ventilation, lab technician training etc etc). The HNO3 vapour reacts chemically with flour constituents (proteins, carbohydrates etc) to ‘develop’ the latent image. Not for nothing do I call it “chemography” which, like pre-digital photography, is a two-step procedure: capture of latent image, followed by chemical development.
I say that 13th/14th century alchemists (especially) had the technology, given that flour was a dietary staple, and Pseudo-Geber/?Paul of Taranto had described the preparation of nitric acid vapour by heating a mixture of saltpetre (potassium nitrate), Cyprus vitriol (copper sulphate) and alum (potassium aluminium sulphate). The imprinted linen could have been suspended in the hot vapour to get rapid yellowing and image development. Alternatively, the vapour could have been condensed in a cooled collecting vessel to get conc. nitric acid, and the linen suspended in the cold vapour above the liquid to get slow colour development as in my procedure, which takes several hours.

Update: Monday May 4

Decided to do a selfie this morning, using the new technology.

Surprisingly, it needs only a thin smear of flour slurry on one's face to get a decent imprint.

Yes, I used a mirror to get this pre-breakfast picture of the slurrified me, immediately before pressing my face down into linen, underneath which was a cushion and several layers of bath towel. Yup, I used LUWU geometry for starters (more predictable, the degree of contact being determined mainly by the deformability of the underlay, there being no manual moulding as in LOTTO. (LUWU = Linen Underneath, Then Underlay; LOTTO= Linen On Top, Then Overlay).

Here's the resultant imprint, before development. shown 'as is' (no photoediting).

Here's the same, after some minor adjustments to contrast and brightness. Note the apparent moustache, and beard and bushy eyebrows. Hmmmm. 

The linen has been folded twice to make a more compact package, using a few stitches of red cotton and is now ready to be suspended in nitric acid vapour.

 Here's the linen inside the vapour chamber. Once can just make out a red stitch. Unfortunately one corner dipped briefly into the nitric acid solution , but that was spotted before there was too much capillary uptake.

All we have to do now is wait. Started vapour treatment at 7:10 am. It's now 13:45, and there's an easily visible browning. I shall leave it for another hour or two before removing, airing, neutralizing  excess acid in bicarb solution, rinsing, drying and ironing.  We shall see what we shall see.

Update  16:10 May 4

OK. Here's the result of my first facial imprinting, using LUWU geometry:

That's the 'as-is' imprint. Anyone would think I had a beard and moustache.
 See my posting from 10 months ago:

http://colinb-sciencebuzz.blogspot.co.uk/2014/07/does-man-on-turin-shroud-really-have.html

 (See there for what happens to the little girl's face when pressed up against glass, such that the photograph taken from the other side becomes an 'impactogram')

Pity about the nose - it may have looked better if the linen had not dipped briefly into the acid solution.

That's a Secondo Pia style inversion of tones (positive to pseudo-negative) using ImageJ Edit Invert.

That's the image after applying some 3D enhancement in ImageJ.

That's the same as above, applying autocorrect in my photoediting program.



Conclusions: the technique shows promise, but falls well short of the TS image characteristics. Next step: I shall have to switch from LUWU to LOTTO. It's almost certainly the passive imprinting technique, relying solely on deformation of the underlay to give moulding of cloth to linen that is responsible for the rather inferior result. LOTTO involves manual moulding, which ensures that important relief is not missed, while at the same time risking excessive capture of sides, resulting in lateral distortion. But then Luigi Garlaschelli believed that a bas relief had to be used for the face. Maybe he's right.


Late addition: I realize from holding the imprint up to the light that there has been failure to develop the brow ridges:

I say failure of development, because they were clearly imprinted with flour, as one can see above. Those missing brows make the image look incomplete.

The linen will now go back in the vapour chamber in an attempt to produce complete development. It may have been the way the cloth was folded that resulted in only partial development.

Result: comparing one with two nitric acid exposures:

How strange. One of the missing "eyebrows" (more correctly brow ridges) has now imaged (viewer's right), but not the left (which shows white due to uncoloured flour).  The reasons for the failure to image first time (both brows) and the second (one brow) are many, due to technical as well as scientific reasons. The whole face imprint is really too big for my vapour chamber if the truth be told.  If only I had one of those tall,  thick-walled glass chromatography tanks. One needs to be more modest with plans right now,  switching to a smaller, less ambitious, less demanding template.

New addition: 17:00 May 5

I was asked by piero on shroudstory a day or two ago whether I'd considered the targets for nitric acid in flour and linen. Lignin was one he mentioned. I'll try and track down the thread in question. Suffice it to say that there's a handy model system I mentioned for checking out lignin. It's pear flesh, the slightly granular feel of which in the mouth is due to clumps of lignified cells ("stone cells"). If nitric acid goes for lignin, those stone cells should show up.

Well, they do:

Pear flesh was crushed onto a strip of linen, and after drying the strip was cut vertically into two sections. The left half was the control (no nitric acid vapour) and the right half was the test. Prediction confirmed: the stone cells show up clearly after nitric acid. Lignin, of which there's substantial amounts in linen,  is indeed a target.  Follow-up studies will be done using the microscope, but not immediately.

Here's the thread in question:

piero

April 29, 2015 at 9:33 am

Reply

Colin,
Where are the controls on linen fibrils (= inspections under a microscope)?
We have not yet seen the controls at “sub-fibre level” …
You know that Shroud image reproduction fails if the features of linen fibril is not the same of the linen fibrils of the Shroud…
Until we have not seen what are the true features (remember also the question of colorless medulla) we cannot speak about the interesting experiments you have done.
— — —
B.T.W. I have read that :
>cold nitric acid, i. e. at ordinary room temperature, either alone
or in combination with certain other acids, will not deleteriously attack
the fiber of flax straw or tow but will attack and reduce the woody portion or shives,
which, as is well known, comprise cellulose fibers associated
with encrusting or adsorbed lignin.
So…
Have you studied the nitric acid action (reaction) on lignin ?
— —
Perhaps we can also try to detect where are (= maps)
the reacted lignin constituents (during the controls on linen fibrils)…
— —
I’m too impatient, I’m sorry…
— —
In any case I believe that new AFM controls on linen fibrils
are based on something more substantial
than the Mark Evans photomicrographs.

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  Colin Berry
  April 29, 2015 at 9:58 am

  Reply

  Piero:I shall be doing all the tests you suggest and more besides, but all in good time. For now I have been content to flag up the results of my pilot experiments with the new two stage imprinting/developing methodology. They show how it’s possible to get a yellow-brown negative imprint from a real person that shows some 3D-properties.There’s a little reverse side colour, but less than I expected, and simple modifications may be able to prevent it altogether. Image superficiality has still to be determined, but then chemical degradation does not always show itself as visible discoloration: there may be less superficial damage to the SCW core of the fibre, the hemicelluloses especially, that are not easily visible, maybe not visibly affecting the ‘medulla’, i.e. most central part, thus distinguishing the new technique from the alleged defect of the contact-scorch model.
  Being aromatic, lignin is a possible target for nitration as well as oxidation. I’m thinking of using the stone cells of pear fruit as a model system for looking at linen lignin, given the ease of seeing them under the microscope. However, it’s not impossible that the result obtained with nitric acid could be reproduced using acid-free thermal development alone, given the right imprinting agent, perhaps not the wheat flour paste used in my preliminary experiments. There’s a vast number of variables and combinations thereof that need to be tested. It will take time.
  
  Update: Tuesday May 5,  07:00
  
  Yes, the face is difficult, at least a fully 3D face, as on a real person or 3D effigy thereof, whether bust/statue/dummy etc As mentioned earlier, Luigi Garlaschelli abandoned attempts to imprint off a real face with his powder frottage model, opining that in a medieval provenance, a bas relief would have been used for the face. Certainly that TS face has a mask-like character, noting especially the abrupt cut-off between cheek and hair (which some explain away as a banding-effect in the linen, a view this blogger has refused to buy into for various reasons).
  
  So where do we go from here?
  
  First, I'm not entirely certain that 100% flour is the optimum imprinting medium (while attractive in pilot experiments for its simplicity). Already there's a hint that an excess of flour tends to cake-on at pressure points, notably the brow ridge, and then for some reason that I cannot explain, resists colour development with nitric acid (I suspect it's something to do with the balance between water vapour and nitric acid vapour: if water vapour cannot readily penetrate the hard cake, then the nitric acid cannot do its job). So today I am going to compare three mixes, using a smaller 3D template than a face or hand. The mixes?  100% flour/water; 100% beaten egg yolk ("egg tempera" as used by medieval artists before the arrival of Renaissance oil piants), and a 50/50 mix of each.
  
  3D template, choosing a new site with  mainly flat (tish) surfaces with interesting detail? I've decided to use my toes. I'll paint the underside with the mix, then the topside, then step onto linen to get a LUWU imprint, then turn the surplus of linen up and over the end of the toes, and mould gently to the top surface to get a LOTTO imprint. It's a model version of the TS itself, note, but using the opposite extremity of the body for the up-and-over reversal of cloth direction. It will also make a more compact package than a face or hand in my vapour chamber!
  
  Update: Tuesday May 5, 19:00
  
  Here's an image I shall shortly post to shroudstory.
  
  
  
  

  

  It's one of some 200 pages in a 9th century gospel that is still in almost perfect condition. The idea that age always degrades inks and pigments is clearly mistaken. An image that is not due to ink or pigment, but a chemical modification of the matrix itself, is likely to be even more permanent.
  
  
   
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