Friday, January 6, 2012

Weblog: further experiments to reproduce, albeit approximately, the Turin Shroud by non-supernatural means, e.g. by thermo-stencilling

I ended the previous blog, posted earlier this morning, with the following words:

"Experiments are underway, which I shall report in real time, i.e. as a (web)log, which was the original meaning and intention of the “blog”, with new items being added to the top, rather bottom.  It’s a little self-indulgent, I grant you, since it supposes that visitors come back for a second or third look. Neither is the end product terribly user-friendly to someone reading a reverse chronology, so to speak. But it’s a suitable format for a reporting a lot of bitty experiments in real time – as evidence that one is still busy and interested – and more user-friendly summaries of chief findings and conclusions can come later. I’ll call it : Weblog: further experiments to reproduce, albeit approximately,  the Turin Shroud by non-supernatural means, e.g. by thermo-stencilling."

So here we go with the weblog, posted in reverse chronological order:

Experiment 2: Given that starch (from white flour") did not increase the charring of cotton by charcoal-mediated thermo-stencilling in Experiment 1, does further addition of glucose have an effect?

Here you see a 4g tablet of glucose (Boots, 92% glucose plus additives) ready to be added to the white flour suspension.

Here's the result, hoping that my make-shift labelling is legible (click picture to enlarge). Note the brown fringe on the glucose+starch area, irradiated with charcoal in columns 1 and 3, but not in the centre column 2. The enhancing effect of glucose was much clearer when viewed from the oppposite side of the cloth, without being obscured by charcoal:

Glucose/starch had a major effect, allowing an intense char patch to form after just 1 minute under the ceiling spot, not seen with starch alone How will the cloth look after washing out the charcoal?

Here's one of the strips after rinsing in cold tap water and drying. One is looking at the top surface, i.e. the one to which the charcoal was applied, the one that was irradiated. With just 1 minute irradiation, with scarcely any charring in the starch/no glucose control (upper half) there is heavy charring in the starch/glucose impregnated area.

Conclusions (and discussion) so far: 

There is a rapid browning reaction dependent on free glucose (as distinct from  starch or cellulose) that requires both the charcoal and the source of radiant heat. It may or may not require oxygen. The brown product seems to adhere firmly to the fabric, i.e. does not strip off with adhesive tape, so one still does not have a match with the reported properties of the Shroud image, but never mind, these are early days. It may well be that the product is simply caramelised sugar, comparable to what is obtained by holding a spoonful of sugar (sucrose) over a flame.

But simulating all the characteristics of the Shroud image is not the sole objective. I used an analogy on another site involving cheese, addressed to an individual who called himself “MouseinaHouse”. If one had discovered, say, Stilton cheese for the first time, and knew nothing of its origin, one might start by discovering how the pale component was formed first, from what ingredients, which starting materials, and worry about the blue veins later.

Why even bother trying to simulate anything regarding the Shroud? Why not let those who wish to regard it as the real Shroud of Christ, and formed moreover by supernatural processes (by no means axiomatic, even if it were Christ’s) ?   Three reasons. Firstly, it was the investigations by scientists back in the 80s that lent a great deal of credibility to the idea that the Shroud may be authentic – that was before the C dating. Secondly, the reasons given for rejecting the C dating that fixed it as 14th century seems perverse to this individual – e.g. to claim that the Shroud had been repaired at the one tiny area that the Vatican had allowed to be sampled.  Thirdly, and the last straw, so to speak, was the manner in which the research by the Italian group was reported to the media, and subsequently received by the blogging community. To say that I am disheartened by the “imaginification”  (provisional term) of science is an understatement to say the least. There are times when modern so-called science, at least in the hands of certain individuals with an over-developed, some might say lurid  imagination seems determined to take us back to pre- Renaissance era.  The fact that the RC Church seems to be playing some kind of role in this, even a relatively non-aggressive one ( I hesitate to describe it as passive) comes as no surprise, given its stick-in-the-mud stance on so many other key issues, notably contraception.
The immediate aim then is to scotch the idea that because “science has not explained the Shroud ” then it’s somehow defied science, and ipso facto there must be a supernatural explanation. For a start, science has much better ways of occupying its time, now that the Shroud has been dated to the 14th century. (Those who claim the sample was contaminated with more modern carbon should realise that the ball is in their court on that one). Secondly, it is unrealistic to expect science to explain every centuries-old item, artefact or otherwise, given no clues as to the materials used, given that age and original processing can alter the characteristics of familiar materials out of all recognition (a cooked onion is an entirely different eating experience from a raw one, and stale bread, even 10 days old, entirely different from bread that is still fresh).

Experiment 1: Does cotton char more quickly under a source of radiant heat if impregnated with a medieval source of "starch"?

What to use a source of starch? Potato starch is ruled out (Sir Walter Raleigh coming along much later). There is one reference I came across suggesting that starch for "starching" clothes in medieval times, and perhaps earlier, might have come from wheat bran. That would makle sense, given that bran has adhering flakes of starchy endosperm, i.e. white flour  - which is not pure starch, needless to say, having some protein there as well. But i was not too worried about the latter, since protein would be necessary if the browning effect with impure starch depended on protein as well to generate Maillard type reaction products. So a level teaspoonful of white flour (self-raising, since no plain flour in cupboard) was added to 250 ml water, heated just to boiling with stirring, then cooled to room temperature. I then steeped half a cotton square in the cloudy suspension, allowed to drain, then dried over the radiator, and then applied my charcoal "paint" as previously described, i.e. a slurry of powdered barbecue charcoal. When the charcoal paint had dried, each black circle was held for 1 minute under a 60W ceiling spot. The charcoal was then washed out with tap water, and the strip of cloth dried and photographed.

Result after 1 minute of irradiation:  the charred area was if anything lighter in the lower flour-impregnated half than the upper control (no flour). That admittedly qualitative result was confirmed a second time.

So despite starch being chemically more reactive than cellulose, there was no enhancement of charring by impregnating with starch. Indeed, there was possibly a little less charring.  I am relieved in a way, since the fewer variables from hypothesised pre- treatments of ancient linen, e.g. during weaving, the better.

The next experiment will be to see whether a simple reducing sugar, e.g. glucose  would affect the outcome. For that I decided to add glucose to the flour suspension, rather than test glucose alone (isolating variables one at a time can come later).

1 comment:

sciencebod said...


Since this post was written, this blogger/retired science bod has proposed a more comprehensive theory as to how the Shroud was created in the 14th century as a ‘holy relic’. The essence of the theory is the making of a thermo-stencil, using linen impregnated with a heat-sensitive chemical substance or cocktail, from a partially-mummified, minimally-skeletonised cadaver possibly in a monastery (think Brno). The desiccated proxy for the crucified Christ would have been heated in an oven of some kind, until radiating sufficient infrared as to be capable of leaving an image on thermo-sensitized cloth.

link to mummy theory