Thursday, April 9, 2015

Modelling the Turin Shroud (medieval fake?). Just waiting now for the nitric acid to arrive.

Yes, an email arrived yesterday to say that conc.nitric acid has been despatched, and might arrive as early as today (10th April) or anytime in the next 10 days (grrrr).

I'm all ready and rarin' to go with my dastardly new approach to modelling the Shroud, one that depends on imprinting a  negative image onto linen from a template (or person?) coated in organic matter (to simulate bodily sweat), not forgetting those blood stains either in all the biblically-correct places. Then follows the crucial step: exposure to a mix of nitric acid and NOx fumes (see posting that preceded this one for the chemical whys and wherefores).

Here's my miniaturized set up for doing the experiment in the garage, with a crude but hopefully effective system of containing the fumes.

Set up for fumigating imprinted linen with vapour phase HNO3/NOx fumes

The conc. nitric acid will placed in the broad-necked bottle - a cm so of depth should do. I may or may not add a few copper turnings to augment the supply of NOx (some forms naturally as a result of HNO3 photodissociation). The imprinted linen will then be suspended in the air space, using the ground glass stopper to hold it in place. Imprinting procedure? I'll paint that brass crucifix with some stiff protein gel for starters (that's powdered gelatin in the green/red sachet), and press down onto the linen to get the negative "body" imprint. (Note that a real body could be used in any scaled-up version, similar to Luigi Garlaschelli's memorable modelling via 'powder frottage' (though he too tested a slurry).

The sealed reaction vessel will then be placed in a gripseal poly bag, at the bottom of which will be some slaked lime or sodium bicarbonate (shown) to sequester any escaped acid fumes. Naturally I'll be wearing a makeshift face mask and goggles, though I survived decades in  chemical, biochemical and medical laboratories without them (but they had fume- and spill containment facilities that my home garage lacks). Wish me luck, all those of you who share my curiosity as to how the Shroud was REALLY made (who may or may not buy into one or more the naturalistic or supernatural  pro-authenticity scenarios that so dominate the world of  "sindonology" and its attendant media circus).

I may tack some more on later, if the HNO3 fails to arrive today, like the numerous boxes that my fumigation model ticks (which doesn't make the hypothesis compelling - merely plausible - but as I've said before, that's the prime raison d'etre of the scientist in my view - to generate hypotheses that are plausible, and then turn them into working models for TESTING.

Late addition (11 April): for the attention of Adrie van der Hoeven

Nitrated cellulose can "leak"nitrogen slowly or explosively

Sunday 12 April  (still waiting for nitric acid to arrive)

Checklist of reasons (work in progress) for thinking there may be some mileage in the nitric acid fumigation model. 

 (Having flagged up the possibility that some chemical changes might be due to oxides of nitrogen, NOx, instead of or in addition to HNO3, I'll refer now simply to the HNO3 model.).

1. If as I now suspect, the TS was an attempt to simulate a sweat and blood imprint onto "Joseph of Arimathea's linen", the latter receiving the traumatised and bloodied body of Jesus straight from the cross, then a chemical approach would have been the obvious way a forger/hoaxer would proceed.

 2. There was already a model of sorts for an image captured as a consequence of facial imprinting, namely the legendary Veil of Veronica, described by Neil MacGregor, until recently Director of the British Museum, as Rome's central icon in the mid 14th century. The presence of the vignette of a Jesus-like face above the word SVAIRE (Latin for face cloth) added to the Machy mould for a Lirey pilgrims' badge variant suggests that an attempt was being made to promote a whole body version of the Veil, arriving a little later than the Veil, immediately post-crucifixion.

 3. How to simulate ancient sweat (1300 years old in the mid 14th century)? It would need to look yellowed, rather faint, and, most important of all, would need not be imprinted (not painted). In other words the final image would not be like a painting, but what today we would call a tone-reversed photographic negative. Secondo Pia's remarkable tone inversion, 1898, is thus explained. 

4. One could use dye imprinting to produce that negative imprint, maybe using a corpse as template or even a life-size bas relief woodcut as suggested by Joe Accetta. However, might there be a less messy way of genberating an image that used a non-pigmented substance for the initial imprinting (allowing a living person to serve as template) and then expose that primary image to a chemical treatment that coloured up the imprint, leaving the background minimally altered. This kind of binary system allows for better control and fine-tuning of the end-result. One can take one's time with the initial imprinting, even doing in stages if desired, eg, head separate from torso. One can also seek to produce a final 'chemograph' by using the chemistry follow-up as a photographer used weak developing solutions, exposing for seconds, minutes even until the required effect was obtained, then adding a neutralising agent to stop the process in its tracks.

5. Neutralising agent? Like a base or alkali that is used to nautralise an acid? Might the developing agent have been an acid? The newly-discovered strong mineral acids, which today we call sulphuric (H2SO4)  hydrochloric (HCl) and nitric acid (HNO3)  were all the rage in alchemical circles in  13th century Europe onwards (the Islamic world probably knew about them sooner,  but the first clear recipe appeared under the (probable) pseudonym Geber, aka pseudo-Geber, thought by some to be the obscure Franciscan monk known only as Paul of Taranto). Might the new proto-chemistry and associated technology have provided a novel means of simulating the supersize-suaire?  Might our Paul of Taranto have been the 'brains' behind it all, whether or not directly involved in the actual hands-on fabrication?

6. STURP described the TS image as that expected of chemically-modified linen carbohydrate, citing as reaction mechanism: chemical dehydration, oxidation, and formation of conjugated double-bonds (the latter comprising the yellow-brown chromophores). Those changes it said could arise from thermal effects ("scorching") or, alternatively, from certain acids, notably sulphuric. Others too have speculated on a role for sulphuric acid, notably Joe Accetta, Joe Nickell and Luigi Garlaschelli.

I tested sulphuric acid and found it wanting: linen tends to disintegrate when intermediate concentration (battery) strength sulphuric acid is allowed to evaporate and concentrate on linen before there is appreciable browning. Hydrochloric acid, being non-oxidizing, is not considered as good a candidate for creating an artificial sweat stain as NITRIC ACID, which is a powerful oxidizing agent. Moreover, it is generally contaminated with the chemically reactive oxides of nitrogen, collectively known as NOx.  What's more the latter are formed when nitric acid oxidizes organic matter, so can arise as secondary products that add to the possible spectrum of  reaction products.

The alchemist known as Pseudo-Geber described in the 13th century the generation of nitric acid fumes from strongly heating a mixture of Cyprus vitriol (cpper sulphate), saltpetre (potassium nitrate) and alum (potassium aluminium sulphate). The fumes could be condensed in a water-cooled collection vessel to fairly concentrated nitric acid with variable water and NOx content. Thus was made something that approximated to our modern day nitric acid. An alchemist who spiltit on his skin would have observed an immediate strong yellow colour. It is not an acid "burn" as such, but a reaction between nitric acid and the aromatic amino acid side chains of proteins, giving the so-called xanthoproteic reaction, the basis of the quick laboratory protein-test. Might that colour change have provided the germ of an idea for simulating a sweat imprint on linen? Might limited exposure to nitric acid fumes also endow linen with an 'aged' look, over and above the ability to turn protein stains yellow?

Provisional model: one paints one's human volunteer or corpse with a viscous dispersion of starch, or white flour, or gum arabic, or milk, egg white etc - in other words an imprinting medium that is carbohydrate and/or protein.  The more gel-like the medium the better. One then covers with a sheet of linen and manually presses the fabric into and around the relief contours. The linen is then carefully pulled back, with its moist imprint, and then, with or without a drying step, is suspended in nitric acid fumes. It is withdrawn as soon as a distinct image of the subject appears against a lighter background.  The image is due to oxidized carbohydrate, possibly with a contribution from nitrated protein. One does not leave in the acid for longer than is absolutely necessary for obvious reasons. After removal the imprinted linen is dusted with powdered chalk or some other agent that neutralizes acid.

7. Fumigation might help account for the otherwise mysterious side strip. (The continuity of weave across the seam joining two sections suggesting that the strip was cut off, then ra-attached later). Might the side strip have been part of a strategy to ensure even coloration with no telltale evidence of temporary supports like poles. pegs etc.

8. Fumigation might account for image superficiality - if one assumes that limited contact to fumes affects the most superficial layer and components of the linen fibre, namely the primary cell wall (PCW) and its relatively open network of polysaccharides (the chemically-reactive hemicelluloses being well represented).

9. The blood first/iamge second chronology is explainable as follows: the subject serving as template was first coated with imprint medium (as above). Bloodstains were then added in all the biblically correct places. Then the combined image was imprinted, such that blood imprinted onto the linen first, residing underneath the imprinting medium.

10. The present appearance of the blood on the TS, looking too red for old blood, and being described as by Adler and Heller as "acid methemoglobin" is explained by by supposing that nitric acid and/or NOx had two effects: first, to oxidise the iron to the ferric state (Fe+3) and then to attach some kind of nitrogenous species to the iron as ligand (NOx?) A possible resemblance to the curing of ham and bacon using nitrites (NO2-, see Appendix below to make pink colours, as proposed earlier by this blogger, albeit  in a somewhat different scenario  (medicinal leech-stored human blood!) could serve as model, while noting Adrie van der Hoeven's inability to find closely matching spectral features. This one-time bilirubin specialist (mechanism of phototherapy for neonatal jaundice)  has previously voiced strong opposition to Adler's poorly documented proposals for implicating "trauma of crucifixion" bilirubin in the permanent red colour of TS bloodstains (bilirubin being notoriously unstable to light and oxygen as Adler himself later acknowledged in his recommendations for Shroud conservation)

11. Deterioration of a strong primary image to a fainter 'ghost' image is catered for, if one supposes that most or all of the imprinting medium flakes off over time, to leave an underlying remnant that is more intense than non-image background.

12. Fluorescence under uv? The Shroud body image is famously non-fluoresent, as I was repeatedly reminded when using hot metal "scorching" as a model. (I was not unduly perturbed, given that fluorescence means nothing centuries after the event: the fluorescent chromophores could have evaporated, oxidized, polymerized etc). However, an entirely different mechanism - chemical oxidation or even nitration by HNO3 fumes and accompanying NOx paints an entirely different picture, no pun intended.The products could be subtly different from those produced by thermal scorching. Alternatively,  the presence of accompanying hydrogen ions /protons from the acid could quench fluorescence.

Monday April 13

Sent this shirty email yesterday to Malcomxxxx, the name that Amazon gave for the retailer supplying the nitric acid  ( I placed my order 10 days ago, and pre-paid!)

Previously when I've ordered through Amazon, Malcolm, 
the goods have arrived on the start date for delivery. 
So I was most disappointed that my nitric acid did not
arrive last Friday or yesterday, and now wonder if 
I may have to wait as long as the last date 
(Wed 22nd! for delivery). Sorry - not good enough, 
not when one is paying over £6 for delivery. 
I had expected better of an Amazon retailer.

People who read my latest blog posting know I'm
waiting for nitric acid to test an important new idea
re the Turin Shroud.

Kind regards

 Colin Berry

Update 13 April

Adrie van der Hoeven (comments) has suggested that Fanti's corona discharge hypothesis might account for the TS image. Here's a couple of images that says it cannot and did not (think hair) :


See comment number 25 addressed to  Adrie re Fanti's corona discharge theory.

Update: Tuesday 14 April

Have just stumbled upon this 1836 report on what nitric acid does to wheat flour versus wheat starch.

 It states that: "Nitric acid has the property of coloring wheat flour of a fine orange-yellow whereas it neither affects the color of fecula nor starch".

Interesting, very interesting. Yesterday I made a syrupy dispersion of wheat flour in hot water, using it to 'paint' my  brass crucifix, and then imprint a near-invisible image onto linen. 
Ready to paint crucifix with wheat flour dispersion in hot water, prior to imprinting the wet image onto linen.

When the nitric acid arrives (!) the linen will be suspended in the fumes. It would be most heartening if the nitric acid were to selectively colour, say, the proteins of the flour and the reactive hemicelluloses of the linen PCW, while leaving starch and cellulose relatively uncoloured.* Might one see a yellow TS-like image against a faint yellow-brown background of slightly and superficially oxidized linen? 

* Being uncoloured would not necessarily mean those white polysaccharides were chemically unaltered. Glycosidic linkages between the glucose units (alpha- and beta- in starch and cellulose respectively) could be hydrolysed by acid/water causing partial depolymerization, as seems to have been the case in my earlier sulphuric acid experiments, in which the linen fragmented under tension while remaining relatively white.  The nitric acid model might account for the observation that Shroud image fibres were more fragile than non-image fibres in Rogers' sticky tape sampling, though some qualifying assumptions would be necessary, e.g. that any starch or other paste used for imaging allowed greater access of nitric acid to the fibre cores, maybe via simple moistening effect, giving more water in which acid could dissolve and accumulate.

Update: Tuesday 10:45  Have just made imprints using (a) egg white and (b) egg yolk (the latter being an approximation to the egg tempera used before Renaissance- era oil paints as a vehicle for powdered pigments. 

Am now feeling badly let-down by the Amazon system that allows suppliers to quote hopelessly unspecific delivery times with 12 day windows, and who fail to respond to one's emails. Where's the customer service  especially when delivery costs are as much or greater than the value of the article itself?

Update Tuesday 08:46:  have just had this terse email:

no its in transit to you  nitric has been held up over
new rules but now sorted

Update: Wednesday 15 April

Still no nitric acid (am).

Discovered yesterday that my specialist (largely dormant) Shroud site with WordPress has an out-of-date banner.  It made reference to my earlier hypothesis linking thermal scorching off a heated template with the Templars (a scorched-on image being symbolic of the slow-roasting of the Templar leaders - Jacques de Molay, Geoffroi de Charney etc- at the stake in Paris, 1314).

While the direct thermal scorch hypothesis had a lot in its favour, despite any number of attempts to debunk it with crassly-designed experiments guaranteed to "over-scorch", there was one major drawback: one cannot easily monitor the degree of scorching to get the optimum end result. It all tooeasily fails the Goldilocks test (not too hot, not too cold).

The new chemical hypothesis being proposed in its place, based on chemically rather thermally-induced oxidation, albeit with similar end results in terms of carbohydrate caramelization etc, does not suffer that disadvantage. Colour development by exposure to chemical fumes, probably HNO3, allows for colour development to be under minutely-observed second-to-second control. If using HNO3 fumes from a chemical reaction between heated metal salts, it also used what in the 13th/14th centuries was state-of-the-art medieval alchemy - surely a point in its favour, and explaining the failure of we modern day science bods to have spotted sooner the application of long obsolete technology.

I have just this minute replaced the banner with the following:

No, a superficial image on linen, least of all a negative imprint, need not defy conventional science, and is not an excuse for conjuring up flashes of radiation or sub-atomic particles from a 2000 year old corpse. Let’s consider the capabilities of medieval technology – or even alchemy.


Update 17:00, April 15
: email message through Amazon from nitric acid supplier:

"it is in transit to you I am trying to find out when"
My reply:
Thank you. You do realize, don't you, that my wife and I are prisoners in our own home,
 not knowing when the acid will arrive? 
This is quite the worst Amazon experience we have had in some 10 years or more. 
It's a form of slow mental torture. Why don't you tell me where you are, 
and let me drive over and collect? I'll happily pay twice to be spared this nonsense.

Kind regards

Colin Berry

Update 08:00 Thursday: new email message from nitric acid supplier:

yes sorry for that but we are sorting out courier 
like amazon do soon sdo you are emailed when it will arrive
My reply:
OK, but it will have to be delivered by the latest date you gave us (Wednesday 22nd April). Why? Because we are travelling after that date, and I'm not willing for nitric acid, no matter how well packaged, to be left with a neighbour. In fact, I doubt whether that would be legal anyway, given its hazardous nature.

Am now looking forward to your email (as are a lot of folk who follow my blog  and who are keen to know what I find with nitric acid). As a teenager, I was able to order acids and other hazardous chemicals from my local pharmacist and take delivery over the counter. Happy days. 

Kind regards

Colin Berry

Update 20:30, April 16

Sent this email:

Could you be more definite about three things please?
First, have you already given the 1 litre of 70% nitric acid 
to a courier, or have you not done that yet?
Second: are you absolutely certain I will be sent an email
in advance, specifying the delivery date?
Third: can you confirm that I will receive the acid
by 6pm, Wednesday 22nd April (the latest day agreed for delivery)?

Thank you

Colin Berry

Back to the science: there's another constituent of linen that needs consideration in the fumigation model. It's lignin.

Lignin has lots of condensed aromatic rings and is a known target for nitration. So there are 2 dovetailing approaches. The first is to examine linen fibres under the microscope before and after fumigation with nitric acid. Might the lignin take colour, and if so serve as a potential signature for exposure to the proposed fumes?  Second, it would help to have a more lignified system as a reference. The obvious one would be a fibrous woody tissue, but that would not lend itself well to a more realistic "image imprinting", Solution? Imprint with a mush of crushed pear flesh? The gritty bits in the fruit are stone cells - clumps of lignified cells.  How will they look under the microscope before and after exposure to nitric fumes?

Update: 18:00 Friday 17 April

Halleluja: The nitric acid has arrived. (I was out when it was delivered so had to collect if from Post Office, after waiting 2 hours for our regular post-lady  to return it to depot undelivered!).

Experiments are under way.  Results initially promising (there being no immediate effect of HNO3 fumes on linen) but then disappointing (no immediate effect of gelatin or flour imprints either). Never mind. These are early days. Maybe it's the liquid acid solution that's needed for development of image, a quick dip maybe, rather than exposure to fumes. Will report preliminary results in a new posting.

Update Saturday  18th April 2015 (for me a red letter day!)

Seems I spoke too soon. The imprint from the hot-water dispersion of wheat flour was left exposed to nitric acid fumes overnight, and removed from its jar this morning for close inspection.

Imprinted image of brass crucifix onto linen, using viscous gelatinized wheat flour, air dried, then developed overnight in nitric acid fumes. (Photo autocorrected in MS Office Picture Manager).

There IS  a faint yellow brown imprint of my brass crucifix, and what's more it's against a beige background (the linen having acquired what might be described as an aged look). What's more there's virtually no imprint visible on the reverse side of the fabric! We have ticked a number of important boxes it would seem.

Update Saturday 21:15

Effect of overnight exposure of linen versus cotton to nitric acid fumes.


More to follow (possibly)?

Update Sunday evening 19 April

Maximal nitration of cotton finally produces nitrocellulose or gun cotton, which is highly combustible (needing no source of external oxygen to decompose rapidly - the nitrate presumably supplying oxygen if needed) What about partial nitration of linen.  While it would not be expected to produce explosive 'nitrolinen', bit might, just might, might it make it more sensitive to heat (like hot pokers. fires in cathedrals?). Are you thinking what I'm thinking?

Here's a quick experiment I have just done comparing the effect of heat (from a ceramic hob) on (a) untreated linen (b) linen exposed to nitric acid fumes overnight. Both were then washed and air dried.

You can see one experiment in progress, with control linen (left) and nitric acid treated linen (right). You can also see the result of two completed experiments.

Conclusion: fumigation with nitric acid renders linen more vulnerable to charring. Might we have an explanation for why the Shroud of Turin has been so 'accident prone' where sources of external heat are concerned, even when inside a silver reliquary with limited oxygen? Are we seeing further evidence that the Turin Shroud image was fabricated using  early alchemical technology that employed nitric acid fumes?

Monday, April 6, 2015

Might fumigation with nitric acid vapour and NOx gases have been used to artificially age the Turin Shroud? Just an idea at this stage.

Chemical prologue (for those with limited chemistry, this introduction can be ignored down to the REAL INTRODUCTION below).

Discovered on googling (nitric acid stains clothes). Click to enlarge.

OK, it's a bit small. What it says is "Spilled some dilute nitric acid on my clothes in chem lab, is there any way to get the yellow stain out?"
My answer (here only): "Nope, except maybe in the same chem lab (using sodium dithionite  for instance as reducing agent to convert to a near colorless amine)."      

                                 R-NO2  + 6[H] -> R-NH2 + 2H2O

Or one could go for the diimide reagent (nascent NH=NH) that Adler and Heller finally resorted to in order to achieve bleaching of the Shroud body image (lesser reducing agents having been found wanting, at least the ones that were tried - although apparently not dithionite).   Correction: 12 April:  Nope. On reading I find that diimide is very specific in its action, targeting -CH=CH- double bonds for hydrogenation to -CH2-CH2-. I was wrong to assume that it would reduce R-NO2 to R-NH2.


One of the curious features of the Shroud is the exceedingly weak contrast between the body image and the background. It's said one has to stand 3 or 4 metres away to discern the image...

Shroud of Turin (from the Turin custodians' own site)

The image colour appears to be an intensification of the background colour, rather than a distinct colour in its own right.  This has led to comments like "image formation is the result of accelerated ageing of the cloth". It's easy to say, but is it true, and if it were, what possible mechanism could be operating to make an image behave in that manner?

Then there's the logistics that any medieval forger had to address in order to pass off a 14th century length of linen  as 1st century. Surely the cloth would have to be artificially aged, but how? If one knew how, then it might be possible to conceive of an imaging system that accelerated in the body image area the chemistry of what was happening in the larger non-image area.

It was a problem that Luigi Garlaschelli addressed in his modelling of the TS image by capturing and imprinting images off live volunteers by powder frottage and variants thereof. He pre-roasted linen in a heated  oven  and there was additional roasting later after application of powder (or slurry). Straightaway one can see how "accelerated ageing" becomes possible in a forgery scenario. Conceiving of a mechanism is a pro-authenticity scenario is another rmatter.

G.Fazio is another author who makes frequent references to the development of colour in background as well as image, with "latency" and "stochastic imaging" being referred to constantly (though I suspect I am not the only one to wish that he would enlarge some more on precisely what he thinks is happening on a physical, chemical and biological level).

More recently, the Dutch sindonological scholar and pro-authenticist Adrie van der Hoeven has devoted a vast open-access paper - some 260 pages no less- to the question of the Shroud blood that is "too red". Her solution? She proposes that the cloth had been impregnated before use with an extract of a yellowish dye (madder), and that blood subsequently mordanted to that dye to produce the permanent colour we see today, 2000 years later (in her view). There is much about that paper and its claims I find interesting and perplexing at the same time, despite (or because of) the wealth of documentation. I only mention it here as yet one more instance in which there has been a focus not only on the image characteristics, but on the phenomenon of a 'pre-conditioned' background for that image. I'll be returning to Adrie's paper again, probably in the third posting in this 'nitric acid' series.

So the question of dual colour, maybe of the same provenance but occurring at different rates, or maybe something more complex (two different mechanisms that just happen to look the same) cannot be avoided.

I propose to address it in two parts, using my new model (see posting immediately previous to this one) - namely the HNO3 (and NOx) fumigation model, and to address background colour first, then image colour, and see if linkage between the two, albeit at different rates OR extents, can be rationalized.

Let's take the Garlaschelli model as our starting point. Heating linen in air to get a discoloration almost certainly involves oxidation. What's more, infrared and other spectral analysis of Shroud image AND non-image areas  has detected the kind of functional groups that are consistent with oxidation, namely carbonyl functions (  ) etc,

But is atmospheric oxidation the only means of oxidizing organic compounds?

Answer: most definitely no. The common mineral acid studies in the last but one posting - sulphuric acid - is an oxidizing as well as dehydrating agent   - but only when its close to its maximum concentration (98%) and HOT. But there's another common mineral acid, namely nitric, HNO3, which is oxidizing over a much wider range of concentration, and which importantly can act at low temperatures too, albeit more slowly that hot. As the previous post relates. nitric acid was known as early as the 13th century in Europe. What's more, it was first prepared in vapour form, albeit contaminated with oxides of nitrogen, by heating a particular mixture of solid mineral salts (nitrates and sulphates) at high temperature. Might the fumes from that reaction have been used to artificially age linen as a first step in faking a 'relic' without even bothering to condense the fumes as recoverable liquid ("concentrated nitric acid" + NOx contaminants).

I propose that the linen was suspended horizontally in a pit (probably) over a retort that was generating fumes from the aforementioned  reaction mixture.  It was withdrawn when the linen was judged the right aged-look colour. (The body image - next posting- may or may not have been exposed to the fumes at the sane time).

So what's the chemistry?  Oxidation of sensitive carbohydrates, especially the more superficial ones of the PCW, could account for the background colour. We'll deal with the spectral analysis later (a tricky area, one I'm not looking forward to, but the nettle will have to be grasped). However, there's a second way that nitric acid can operate, especially when it's concentrated and/or relatively water-free in the vapour state - namely by nitration of protein, notably of aromatic amino acid side groups. Tyrosine is the one that dominates the literature, but tryptophan and phenylalanine occasionally  figure too.

Here's a schematic diagram of the end-result of nitration  (e.g. substitution of NO2 for H) of tyrosine in a protein.

Nitrated tyrosine side group in a protein - colour coded

There are two systems where protein nitration occurs to make a yellow colour - one wll known, one less so, except to clinical biochemists.

Concentrated nitric acid acid quickly does this to unprotected skin. It looks like a burn, but is in fact a xanthoproteic reaction to produce nitrotyrosine and other nitrated proteins that are bright yellow in colour.

The other, which I merely flag up at this stage, is the modern focus on nitrotyrosine as a marker for the overproduction of active oxygen and nitrogen species in a range of disease conditions. on which there is a growing literature. In brief, the gas nitric oxide, NO, is an important regulator in our body tissue. affecting for example the tone of smooth muscle in our arteries and thus blood pressure. However, an excess of NO can react with the active oxygen species superoxide,  O2-,  to form the peroxynitrite , ONO2-,  which can then attack a number of sites including the tyrosine residues of proteins, forming the same nitrated entity that caused the yellow skin in the above photograph. Should my current hypothesis ever find traction (these are early days)  be prepared for some pro-authenticists to seize upon in vivo nitration as a marker for what I call crucifictional physiology, comparable to Adler's outrageous ideas on 'trauma bilirubin', mere airy-fairy speculation that far too many, the STERA president included, tout as if established fact.

Enough of the chemistry. Let's look at more practical details of what's being proposed. Might the Shroud linen have been fumigated before acquiring the body image in order to give it an aged look? If so, how would that have been achieved in practice to ensure an even coloration, with no tell-tale defects that would arouse suspicions?  Let's imagine that a pit was dug into the ground, into which NOx and nitric acid fumes were led from a chemical retort, and that a pole had been placed or inserted over the top on which to peg or drape over the linen (later covered with a lid of some kin or large sheet (or sheets) of glass through which to check on progress. There's a problem. Pegs, if used, would have protected part of the linen, leaving pale areas that look like 'negatives' of the pegs. If draped over, there would also be a contact zone that was protected from the fumes.Might we perhaps have a novel explanation for the Shroud's mysterious so-called 'side-strip', or 'selvedge' as referred to by Adrie van der Hoeven. It's just visible in the photo at the top of this posting as a faint line extending horizontally from the corners of the cut-out portions of the fabric, some 8cm across its small dimension. It's in fact a seam that can be unpicked. Importantly, it's the same fabric both sides of the seam.

Anyone who's anyone in Shroudology has pondered on that side strip and offered opinions, and there's no time to discuss them all. Let's take just two of them. First, there was Bernard Power's. He thought the Shroud linen's width was too wide for the slab on which the body of the crucified Jesus lay in its rock tomb, so part of it draped vertically over the side facing the viewer. He proposed that an 8cm wide strip was removed from the edge of the long dimension (i.e. 4.4m x8cm) and then sewn back onto the opposite side.

Adrie rejects that explanation, claiming that the continuity of weave both sides of the seam is too good for Power's scenario to be true. She claims the strip was cut off, then immediately re-attached by stitching. Why would anyone do that? Her explanation? What we called the Shroud linen was originally intended to be a garment, and 1st century Jewish/Pharisaic law required that garment cloth had at least one seam.

I have a rather more mundane explanation, which can be accommodated to Power's side-to-side switch OR to Adrie's in situ detachment/re-attachment. Let's suppose the Shroud linen had been pegged out and fumigated, and then the unsightly peg marks discovered. Solution: cut off and discard the border with the peg marks, and replace with the same width cut from the opposite side. How will one explain away the seam? We'll come to that in a minute.

In the Adrie scenario, the problem of peg marks was foreseen. How can one suspend the linen in fumes to get even coloration without peg marks (or pole-marks)? Answer. Cut a strip off the edge, then re-attach loosely by lengths of strong thread, and use those threads to support the linen  - main section and strip - during fumigation. Later, the bridging threads are removed and the strip re-attached.

How to explain the border with the seam? The Lirey Pilgrim's badge, circa 1357, issued to commemorate the first undisputed exposition of the Shroud in a tiny French hamlet provides the answer, It is being held out vertically for display by hands that can an be seen gripping the edge. The owners of those hands are missing, due to that part of the badge being missing, but the Machy mould for a second Lirey badge shows the hands are those of men in clerical attire. It would have been an easy matter  to explain why there should be a segregated part of the Shroud set aside for gripping manually, citing reasons to do with this or that practical consideration for safe or respectful handling of an allegedly 1300 year old burial shroud.

There;s another practical aspect that needs addressing: the suitability of using a strong oxidising acid and its precursors (NOx) to age linen. Wouldn't that damage the fabric, making it later prone to disintegrate, comparable to the effect that evaporating sulphuric acid had on linen (not cotton) in my recent experimentation (see last but one posting)?

There's a big difference between sulphuric and nitric acids. Soak linen in dilute sulphuric acid, and will still look wet days later, and indeed is wet, as can be confirmed by touching (then quickly rinse off with runnin g water). Why is that? It's because dilute sulphuric acid becomes more concentrated on evaporation, due to evaporation of water, while the relatively involatile H2SO4 stays behind. That is far less likely to happen with nitric acid - HNO3 being more volatile (prone to evaporate) than H2SO4.

Boiling points: nitric acid: 83 C.  Sulphuric acid: 337 C.

Even pure sulphuric acid has a vapour pressure of less than 0.001 torr at 25 °C and 1 torr at 145.8 °C. (That's tiny, considering that a torr is a unit of pressure equivalent to just 1 mm of mercury in a barometer. Typical atmospheric pressure is a whopping 760mm mercury).

Even if there were traces of HNO3 left in the cloth days or weeks after fumigation, there are chemical mechanisms too that remove it. HNO3 is prone to decompose, not only when heated but when exposed to light. It breaks down to gaseous end-products that can escape:

4HNO3 (liquid)  ->  4NO2 (gas) + O2 (gas)  + 2H2O(liquid) 

(Terms in brackets indicate physical states at normal temperature and pressure).

As the above process occurs the acidity will gradually decrease. But in any case, the ageing process on fumigation would have been closely monitored to achieve minimal discoloration only . That would have limited the amount of unreacted nitric acid left in the fibres of the cloth. It's not inconceivable either that the treated cloth would have been treated with an agent or treatment known to neutralize and decontaminate acid, e.g. a light dusting with chalk. (There we have, in passing, an alternative explanation  for the allegedly high levels of calcium on the TS).

OK, that's do for now. The next posting(s) will be asking if and how the body image could have been imprinted using HNO3/NOx  chemical technology as well, either subsequent to pre-ageing of linen, or even simultaneously. At some stage the known visible and infrared reflectance spectra of the TS image and background will need to be matched against available literature values (limited!) for yellow nitrated tyrosine and other aromatic amino acids in proteins. We'll then need to consider what the target proteins are or were.

Here's a screen shot preview for starters (the full version is behind a paywall). It's the infrared absorbance spectrum of free nitrotyrosine (in acid) versus tyrosine. Click to enlarge.

Personal credo of this retired science bod: we scientists exist primarily to propose plausible and testable hypotheses. I offer that as a plausible hypothesis, as indeed I offer my novel but as yet untested nitric acid/NOx fumigation model of the Turin Shroud. It may or may not stand up to testing. If it doesn't, I'll simply abandon it, and try to think of something else. Anything's better than simply resorting to "Oh, it had to be supernatural". My beef is not with the supernatural as such. It's with those who use pseudo-science to push their agendas (any agendas), or who simply have lazy minds, or who despise scientific curiosity (or "meddling")...

Finally, there have been many false dawns for this blogger since beginning his Shroud project at the tail end of 2011 (some 250 postings to date, here and on his main specialist Shroud site.  In fact there have been so many false dawns that he's occasionally felt the need to install  motion sensor night lights in his head simply to see where he's going 24/7, if only to avoid bumping into solid fixtures and fittings in the all-pervading gloom. Maybe the HNO3/NOx hypothesis will turn out to be yet another false dawn, like thermostencilling, thermal contact imprinting, Maillard-assisted imprinting, alum-mordant -assisted imprinting etc etc.

But kindly note one thing, .Joe Marino: he has not yet reached a dead end, as you so engagingly put it. There are always new avenues to explore, and NO - (that's NO the negative, not nitric oxide) invoking the supernatural is not one of them. Now that's what I call a dead end, at least in experimental/scientific terms. One shouldn't need to remind him of that.

Update, Tuesday 7th April

Response so far to the new thinking? Absolutely none,  despite posting the following to the shroudstory site two days ago. Yes - a complete silence reigns. It's eery!

April 5, 2015 at 8:42 am
The timing is unfortunate (this being Easter Sunday). However, having spent 3 years in attempting to suss out the peculiar TS image, and been told by fellow scientists (well, some at any rate) that it has to be “supernatural” I can scarcely contain my growing conviction that a solution is finally within reach. A hint was provided in the previous comment or two. The question is: how to communicate the new idea? A fait accompli set out point by point? Sorry, not my style. I don’t do fait accompli Science works by hypothesis, experiment, interpretation, modification of hypothesis etc etc. There’s no room there for springing a fait accompli on folk. Better to build the story in easy instalments, ones that address the many disparate peculiarities of the TS image that have to be accounted for. (The new “hunch” could of course be wrong, and quickly demonstrated to be so, given it is capable of immediate testing by existing means were there free access to the Shroud. But there’s not, and indeed this blogger/retired biomedical scientist is not even able to wander into that Turin Cathedral simply to see the TS with his own eyes, so feels it’s not a huge and shameless imposition on folk, certainly on this ‘cutting edge’ site to say what’s in his mind, and to do so sooner rather than later.
There are two ways I can lift the lid on the new thinking. One is to post on my own site, and (no disrespect to Dan) hope it gets reported here with no details neglected or glossed over – detail being crucial in scientific research. The alternative is to drip-feed the new model here as a series of comments, as a continuation of this particular thread (why not, since Dan’s posting links to my site?) and not bother composing a posting to my own site until the feedback here has appeared. Might that not be a more internet-friendly and democratic way of doing things, while admittedly a far cry from the traditional route via peer-reviewed publication in journal articles (abstract only, cough up $$$ to get behind the paywall). What do folk think? Fait accompli on my site, or drip feed to this one?
Title for the new idea? How about: “A novel NOx/protein fumigation model for the Turin Shroud.” NOx represents the binary mix of nitrogen oxides (NO and NO2) that react together with water and oxygen to form nitrous and nitric acids (HNO2 and HNO3 respectively), or alternatively are generated in a reverse reaction when preformed HNO3 from a reaction mixture in a distillation flask dissociates at high temperature. Nitric acid reacts quickly with proteins that contain aromatic side chains (tyrosine, tryptophan etc) to form yellow ‘xanthoproteic’ reaction products. Both light sepia TS non-image background or darker, more intense TS image could be xanthoproteic reaction products formed by NOx fumigation of intrinsic linen OR extrinsic non-linen protein, or both. Several boxes can be ticked (e.g. lack of image fluorescence, even the Shroud’s mysterious side strip).
Comments invited re the best strategy for reporting a distinctly new angle on the TS body image – blood will have to wait until later. Happy Easter.

Further thought- 7pm Tuesday

Some might consider, with some justification, that too many eggs are being placed in the one basket. What if the spectral characteristics of the image and/or background do not fit with nitrotyrosine, or any other 'nitrated' entity? Does that mean having to abandon completely the nitric fumigation model (which has quite a lot going for it in general terms, as far as producing a 'ghostly' image is concerned). In fact there's at least one other chemical system/interaction that could deploy nitric acid, but which does not require protein or any other 'nitratable organic compounds. It uses green vitriol, known to medieval alchemists, and indeed conjectured to be the source of the first sulphuric acid. Green vitriol  is known today as iron (II) sulphate heptahydrate, i.e. FeSO4.7H2O, and I already have a large bag of it in the garage (it's cheap to buy as moss killer for lawns) and in fact used it 3 postings back to test out Joe Accetta's ideas re ink imprinting (the iron forms an intense black solution when added to extracts of plants tannins, like boiled/sieved pomegranate rind in my experiments - a substitute for medieval oak galls). Nitric acid turns green iron(II)sulphate brown. It's a simple oxidation of iron(II) to iron (III), or ferrous to ferric in the older system of chemical nomenclature. It might be possible to devise an imprinting medium based on iron(II) sulphate that is then "developed" by exposure to nitric acid fumes until the desired colour is achieved. Admittedly one would then have to find a way to remove the unreacted iron (II) while leaving the iron(III) in the fibres of the cloth,  but that's not impossible (washing etc).

Later still, 8:20pm  This posting with a video clip (which I'll view later) has just appeared on shroud It's a puff for Professor Fanti of Padua University and his claim, based on (dubious) chemical alternatives to radiocarbon dating, that the TS is much older than its apparent C-14 content would indicate. His new date range? It centres on 33BC +/- a few centuries either side. Well well.

But there's a snag, if one assumes for the sake of argument that my model is correct. Exposure to nitric acid fumes would wreck all his chemical clocks that rely on natural oxidation and ageing. That's especially true of the test, one of 3 as I recall,  that measures fibre mechanical strength. Two seconds of exposure to fumes might do more oxidative damage than two centuries exposure to atmospheric oxygen!  One could go further and say that the assumed correctness of the radiocarbon dating (1260-1390)  and the evidence for 'super-aged' fibres is supportive evidence for a manufacturing process that employed a powerful chemical oxidant. Sorry Prof Fanti.  You win some, you lose some, as every scientist knows only too well.

10:00 pm  One thing I've been keeping on the back burner while writing this and recent blogs is a hunch I acquired about a year ago as to the way the Shroud was supposed to be interpreted by the first cohorts of pilgrims arriving at Lirey. No, it was not meant to be seen as a "painting", as suggested by Charles Freeman, and certainly not executed as such. It was meant to be seen as a bodily IMPRINT (thus the negative light/dark reversed character) and, more specifically as a SWEAT imprint acquired when the NEWLY crucified Jesus was transferred from cross to Joseph of Arimathea's linen., the latter serving as a kind of makeshift stretcher or body bag or transport. Here's a link to a late Nov 2014 posting, just one of many on the sweat imprint idea:.

In other words, our medieval artisan set out to SIMULATE a sweat (and blood) imprint, and did so using the most up-to-date chemical, or rather alchemical knowledge available at that time, say late 13th to early 14th century. Tomorrow's post will flag up out some ideas about how that may have been done, using nitric acid fumes as a "chemical developer" for the artificial sweat to create what might be termed a 'chemograph', fumes that may have chemically modified the blood at the same time to account for its odd character ("too red" etc).

Who might have had both the alchemical technology AND the audacity to produce a fake relic that still holds millions in thrall to this very day?  The answer I believe is obvious. See the posting that precedes this one. The Shroud was I suggest the work of the Franciscan monk  Paul of Taranto, the same man as the one previously described as Pseudo-Geber according to some modern scholars. It was  made possible by Paul's technology for generating nitric acid either as fumes or condensed liquid. Whilst I've so far been able to find next to nothing about Paul the man, or even his birth and death dates, there's plenty on his philosophy and world view, and some of it looks very, very interesting.  Expect a posting at some stage that puts together these hunches, together with further findings for or against the hypothesis.

Update: Wed 8th April

Have just responded to Max Patrick Hamon on with this:

Max patrick Hamon
April 8, 2015 at 4:41 am
Is it for convenience’s (or gross approximation’s) sake too you keep asserting a medieval super-genius

forged the TS image?
April 8, 2015 at 5:09 am 
In fact there is a possible candidate for that ‘medieval genius’ . Max, provided you accept an alchemist with a sideline in deep philosophical discourse. I refer to the 13th century (pseudo) Geber.
Geber, who in his day was regarded as an alchemist, and thus viewed with deep disapproval by the Church, had used Geber as a pen name (it’s complicated, being an attempt it would appear to pose posthumously as an much earlier Arab alchemist). However, a strong case has been made for identifying the pseudo-Geber as the Franciscan monk, Paul of Taranto.

Geber/Paul are credited with the first clear recipe for generating nitric acid and accompanying oxides of nitrogen by calcining a mixture of metal nitrates and sulphates, initially in the form of fumes from the reaction vessel. I am coming round to the view that those fumes could have been used to produce the image we see on the Shroud – as oxidation products of carbohydrates – and possibly even nitrated products of protein (yellow xanthoproteic products can be formed by nitration of aromatic side chains of tyrosine, tryptophan and phenylalanine).
See my most recent two postings for details.
(Links inserted)

Conc.nitric acid is on order. Rest assured I’ll be testing the hypothesis at the earliest opportunity, at some risk to my lungs.