|1. Make a thin slurry of plain white flour with cold water.|
|2.Paint skin with slurry|
|3. Drape linen over coated skin|
|4. Gently pat linen to mould to contours.|
|5. Peel back linen. Flour imprint scarcely visible at this stage.|
|6. But most of the slurry transfers to the linen, being sticky.|
|7. Press with hot iron on opposite side from imprint (highest temperature setting) on part of the flour imprint. Leave one side cold as control.|
|8. Result - a faint image, reminiscent of the Turin Shroud.|
|9. Is the image wash-resistant? Detach a test portion (right)|
|10.The imprint withstood 15 minutes immersion in cold water|
|11. Would it withstand washing with soap?|
|12. Answer - yes, though a little fainter.|
This is very simple technology, needless to say, requiring only plain flour and a hot flat iron (smoothing irons must surely have existed in the 14th century, when the Shroud of Turin was first put on public display (Lirey, France, circa 1357).
Regardless of authenticity, this simple demonstration is my answer to those investigators in Italy and elsewhere who claim that the image of Shroud of Turin can never be reproduced under laboratory conditions. It CAN be reproduced, at least as regards macroscopic aspects, in one's own home living room. Microscopic characteristics need further investigation.
Update: Sunday 21 June
Mechanism of enhanced browning in image zone? Presumably a non-enzymatic Maillard browning reaction between reducing sugars and proteins.
reducing sugars + protein (or free amino acids etc) -> complex mix of yellow melanoidins
(The reducing sugars provide reactive carbonyl groups , the protein etc provides reactive amino groups)
But there are 3 combinations that will need to be considered that are not mutually exclusive, i.e. two or more may be operating simultaneously:
Reducing sugar (white flour) reacting at high temperature with protein/amino acids (linen fibres)
Reducing sugar (white flour) reacting at high temperature with protein/amino acids (white flour)
Reducing sugar (linen fibres) reacting at high temperature with protein/amino acids (white flour)
The fourth combination, i.e. reducing sugar (linen fibres)/protein/amino acids (linen fibres), is not listed since that would account only for the slight "scorching" of background linen one sees outside the image areas, i.e. background coloration.
There is also the possibility that proteins are not involved, that the tan coloured image is the result of pyrolysis (aka caramelisation) reactions involving carbohydrates only. Expect to see a postscript here shortly (a few days at most) on the effect of replacing whole white flour with gluten-free starch. The latter will use starch granules isolated from white flour by water-washing and sedimentation, as described in an earlier post here in which nitric acid was used for colour development of the primary imprint, dubbed the "stick 'n' stain" variant of the generic 2-stage imprinting/developing model.
Speaking of which, nitric acid that is, which was the first means of Stage 2 colour development to be reported on this site, its use is emblazoned on the banner of this blogger's specialist Shroud site., despite being a vicious corrosive reagent towards human flesh,.
|Present banner (June 2015) on my shroudofturinwithoutallthehype.com site|
But which of the two chief variants of 2-stage imprinting (3 if one counts the promising results with hot limewater) would medieval forgers have been more likely to use:(a) the use of a hot smoothing iron, as described here, or (b) exposure to nitric acid vapour or solution?
Is the hot iron (or maybe an oven roasting) more likely than treatment with a novelty chemical reagent that was probably little known in the 14th century outside of alchemists' secretive laboratories? Do I need to substitute a collage showing the steps in this posting for the one you see above, if only to flag up the variant that is more user-friendly, i.e. safer to deploy in one's own 21st century home should any readers be minded to check out the claims made here?
I shall make the collage, but may not replace the present one immediately. Better maybe to hold fire on whether the putative forger of the Turin Shroud was more physically or chemically minded. (He did not need to know the chemistry of Maillard reactions to make an educated guess that a hot iron would scorch a flour imprint more readily than the linen on which it was deposited). (Afterthought: I could make a twin-collage, showing both the "iron" versus "non-iron" method. There's no need to make an instant decision as to which was more probable in the mid-14th century.)
But there again, our medieval forgers, even if alchemist- (aka proto-chemist)- assisted, did not need to know the molecular mechanism as to how nitric acid reacts with proteins to give a yellow colour (xanthoproteic reaction). All they needed to know was its reputation for staining skin yellow, and then have seized on that as a way of simulating an ancient then 1300 year old whole body imprint (as sweat) by imprinting with ANY convenient organic substance - a proxy for sweat - and developing chemically with any reagent that might turn it a permanent non-fading yellow.
Here's a link to a site on the history of ironing. It's not entirely clear when the box iron, loaded with hot charcoal, first put in an appearance (one trusts they knew to keep the windows open, to avoid deadly carbon monoxide poisoning).
Box irons are still used to this day, e.g. in India:
|Box iron with lid raised to show smoking hot charcoal|
Might there not have been a risk of getting red hot embers onto one's prize linen? Is anyone thinking what I'm thinking. Yes, those "L-shaped poker holes".
|Source acknowledged(with Autocorrect in MS Picture Manager): http://theshroudofturin.blogspot.co.uk/2013/03/the-shroud-of-turin-26-other-marks-2.html|
Later thoughts: prompted by the result of the wash tests with water then soap/water, one could hypothesize/rationalize as follows. When the imprint is heated with the iron, there are two distinct Maillard reactions - one with the flour "impurity layer" and one with the linen itself, each providing carbohydrate, protein or both. It's the browned coating with its Maillard/caramelized products that washes off with soap and water, but those associated with the linen fibres stay put. It is presumably the latter we see today in the faint, scarcely visible image. Originally, the image would have been more intense, due to the impurity derived carbohydrate and/or protein. For Charles Freeman to claim as he does that investigators have totally ignored image degradation over the centuries (to sustain his scientifically-bankrupt line that the TS is 'just a painting') is not only wrong. It is insulting. Maybe if he took the time to read the scientific literature, instead of dismissing scientists as art history philistines, which they may or may not be (it being of little consequence and probably irrelevant where the enigmatic TS negative imprints is concerned) he would see that image degradation is something that always has to be factored into everyone's thinking, and indeed is and has been, whether formally acknowledged or not, at least where this investigator is concerned. The man is way, way out of his depth in attempting to brush aside decades of detailed scientific investigation that shows the TS image is UNIQUE, and cannot therefore be subsumed into art history, least of all when that requires the qualifying assumption (read fix) that the original artist's pigment have (conveniently) detached leaving no trace of their original presence, merely an unexplained negative image (which Freeman mistook at least initially to mean left-right reversed, as in a mirror image). Forgive my saying Charles, but you're an incorrigible time waster.
Update: 21 June
Have separated starch from gluten, and tested them singly and in combination with a hot iron. No obvious browning reactions were seen. It might be soluble flour proteins that are needed for a Maillard reaction (gluten protein is highly insoluble, which explains why it's so easy to separate from starch granules, simply by washing out the latter from a stiff dough with water). Soluble reducing sugars of flour may also be needed, with intact starch not substituting, even at high temperature.While it's of interest scientifically to understand the chemistry, in particular to confirm or disprove the presumed Maillard reaction, ignorance of the precise chemistry does not detract from the hypothesis proposed, namely that the TS image was formed by a browning reaction in an extraneous organic material imprinted onto linen, probably flour glue (its adhesive properties making it an imprinting medium par excellence).
Update 22 June
Here's a headline that appeared in yesterday's Daily Mail (or Daily Wail as some prefer to call it!).
Note there was an estimable 127 comments when I did that screenshot a few minutes ago. Some of them are mine (as Colin Steven, the first two thirds of this blogger's full name). Began with a brief plug for the latest 'hot iron' model, it being simplicity itself, though the Mail does not as I recall permit links so I chose not to risk it. Got into a quite upmarket discussion (for the hard-bitten, don't-give-me-that-bullsh*t regular clientele of the Mail that is) with one "Birchy of Blackburn" who says he knows this blogger from "Mr. Porter's site". Has he left comments there one wonders? Can't say as I recall input from the north of England.
Thank goodness those green up-vote arrows and red down-vote arrows of the Mail are not copied more extensively. They seem to bring out the worst in people. I much prefer systems like Disqus, where a down-vote simply reduces the tally of up-votes.
Speaking of which (Disqus) here's an opportunist comment placed just a minute ago on the Disqus-hosted Telegraph: