Sunday, May 3, 2015

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:

May 3, 2015 at 5:24 pm
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.
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:

  • May 3, 2015 at 8:04 pm
    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?
May 3, 2015 at 11:20 pm
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:

 (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:

April 29, 2015 at 9:33 am
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.
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.

  • April 29, 2015 at 9:58 am
    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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