Simple physics says there are 7 ways of producing a scorch on linen

Prompted by some near-incomprehensible jargon in “stochastic” theory for Shroud image formation, I thought it might be a good idea to go back to first principles. One has to maintain one’s scientific compasss…

The three mechanisms of heat transfer - conduction, convection and radiation.

The three mechanisms of heat transfer – conduction, convection and radiation.

Comments posted to Dan Porter’s shroudstory.com site

November 13, 2013 at 11:13 am | #64

Back to school:

Heat transfer 101 (from the BBC’s site)

http://www.bbc.co.uk/bitesize/ks3/science/energy_electricity_forces/energy_transfer_storage/revision/5/

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Thermal energy can be transferred by:
Conduction
Convection
Radiation

Conduction

When a substance is heated, its particles gain energy and vibrate more vigorously. The particles bump into nearby particles and make them vibrate more. This passes the thermal energy through the substance by conduction, from the hot end to the cold end.

Convection

The particles in liquids and gases can move from place to place. Convection happens when particles with a lot of thermal energy in a liquid or gas move, and take the place of particles with less thermal energy. Thermal energy is transferred from hot places to cold places by convection.

Radiation

All objects transfer thermal energy by infrared radiation. The hotter an object is, the more infrared radiation it gives off.

No particles are involved in radiation, unlike conduction and convection. This means that thermal energy transfer by radiation can even work in space, but conduction and convection cannot.

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Thank you Auntie BBC. You can go now.

Only 3 modes of heat transfer? Now, can anyone guess what’s coming next?

Hint: in the real world, there are in fact 7 ways of transferring heat in any given situation, providied it’s an extended, i.e. non-instantaneous time frame, not just 3.

Think SM, DM and TM modes of presentation (of which there are 3, 3 and 1 respectively).

More later.

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November 13, 2013 at 12:50 pm | #67

Figured it out yet?

In the real world, on a real finite time scale, there are in fact 7 single or conjoint modes of heat transfer:

Single mode

Conduction only
Convection only
Radiation only

Double mode (in either order)

Conduction /convection
Radiation /conduction
Radiation /convection

Triple mode (in any order)

Conduction/ Convection/Radiation

Next step: to see how each of these 7 modes can operate in principle or in practice to dehydrate linen carbohydrates, producing a yellow or brown discoloration of the fabric (heat scorch). But before doing that, a few words are needed re Rogers’ ‘naturalistic’ Maillard reaction, excluded deliberately from the above list, whether assisted or not in a thought experiment by a small post-mortem temperature rise .

(Expect another instalment re Rogers within the hour).

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ovember 13, 2013 at 1:45 pm | #68

So why no listing of the Maillard reaction? Answer: it’s not simple heat transfer. It posits a chemical reaction between amine and reducing sugar (almost certainly with unfavourable kinetics and possibly even thermodynamics at environmental temperatures, one that would benefit greatly from an appreciable temperature rise above immediate post mortem body temperature, e.g from 37 C to at least 60C or higher). See Lea and Hannan (1949) in Biochem.Biphys Acta for early studies with model systems.

It is outside the scope of this enquiry unless the amine and reducing sugars are specified, and, more importantly, have left identifying traces on linen (e.g, a surplus of nitrogen in image-bearing areas, or unreacted reducing sugars in non-image areas).

Raymond Rogers omitted to do these simple tests, making no attempt to test for nitrogen, and making vague and unsupported claims for the presence of traces of “starch” (which is in any case not a reducing sugar, and would have to be extensively degraded to fit that description).

This contribution is about known physics, not speculative chemistry. In any case, even if there were chemical evidence for Maillard products on linen, it would still be highly problematical as to how homogeneous imaging could have taken place, as others have pointed out previously. In short, the evidence of the naturalistic model based on Maillard browning reactions is tenuous to say the least.

Another instalment to follow, later this evening.

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November 13, 2013 at 2:46 pm | #72

Fourth instalment: So what examples can one cite for the more complex non-single modes of heat transfer listed that defy simple or rather simplistic analysis?

Here’s just 3 for starters, all “conjoint”.

1. Garlaschelli technique : baking in oven for 3 hours at 215 to 220 degrees C of linen that carries a temporary frottage (rubbing) imprint using ochre pigment from real human being (plaster of Paris template for head) .

Professor Luigi Garlaschelli

Professor Luigi Garlaschelli

Garlaschelli, 2010 (Life-size reproduction of the Shroud of Turin and its Image, Journal of Imaging Science and Technology, 54(4)040310-040314.

One sees differential browning – area under ochre pigment and background both acquire aged look (browning) but the pigmented area more so than background.

Shroud image (left). Garlaschelli's reproduction with medieval technology (right).

Shroud image (left). Garlaschelli’s reproduction with medieval technology (right).

The pigment can be washed out – or drop away naturally – to leave a faint scorched-in image, or as LG described it, etched (possibly assisted by acidic impurities in the ochre that aid dehydration reactions)

Likely mechanism: dual (convection/conduction, possibly accompanied to a minor extent by radiation/convection).

2. My own ‘thermostencilling’ technique, in which a dry charcoal sketch or slurry painting is irradiated with heat (and light) from an incandescent light bulb, to produce a scorch under the charcoal.

http://colinb-sciencebuzz.blogspot.fr/2012/01/how-to-make-your-very-own-turin-shroud.html

Paint on desired "image" with charcoal slurry

Paint on desired “image” with charcoal slurry

Again, the charcoal can (though occasionally with some

difficulty) be washed out to leave the scorched-in image.

After irradiation with heat and light, then washing to remove the charcoal thermosensitizer

After irradiation with heat and light, then washing to remove the charcoal thermosensitizer

Likely mechanism: radiation/conduction

(Only later did I realize that my thermostencilling was similar in principle to GLs, the difference being the form of thermal energy used to heat up the sensitizing solid.

3. Direct contact scorch e.g. from pressing a heated metal or ceramic template against the linen.

Likely mechanism: conduction (primarily), possibly (probably?) with secondary convection (superheated steam and other pyrolysis gases produced by dehydration of linen carbohydrates in direct contact with hot metal, producing some linen degradation at points not in immediate contact, especially deeper into the interstices of the weave).

Having listed just three, non-single mode, i.e. more complex conjoint mechanisms, the next step is to go back to the summary of the Fazio/Mandaglio paper,(s) and see what is true but not new, and what is new but not true. At this stage there need be no consideration of the nature of the scorch at the microscopic level, which is probably more a matter of impression unless or until accompanied by high magnification pictures.

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November 13, 2013 at 6:40 pm | #77

Good evening Thibault. I still have a few more observations to make regarding the fundamental physics, but the main point has been made, namely that while there are only 3 textbook mechanisms for heat transfer, there are in fact 7 when you put them together in their various combinations. That gives one a greater range of options for creating subltety if setting out to reproduce the Shroud image, even if we have still not achieved that to everyone’s satisfaction (probably an unrealistic objective anyway, given that some view the modelling as having to meet aesthetic as well as scientific criteria).

One needs also to be mindful of the effect of ageing on the Shroud image. As Luigi Garlaschelli has pointed out, we are not seeing the image as it would have appeared at its moment of birth so to speak. To give just one example: we know that image-bearing fibres are mechanically weaker than non-image fibres, probably more brittle and prone to fracture. So when we see a scattering of pale yellow fibres we must not be too quick to suppose this implies some profoundly mysterious process of image-imprinting. It may merely mean that more densely scorched images have broken off in the course of time, and we are simply seeing the ones that have survived through being only minimally-scorched.

Do you suppose that Fazio and others, when speaking of discontinuities, are merely using a different term for the so-called half-tone effect, which arises from having all image fibres uniformly pigmented, with image density being due to numbers of image-bearing fibres per unit area only? Or is there some other meaning with maybe transverse banding as well, such that a single fibre could be uncoloured for some of its length, and then abruptly become coloured? But if that were the case, would that not be totally consistent with contact scorching?

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From David Goulet:

November 13, 2013 at 10:50 pm | #75

If anyone is doing another heated statue experiment, I’d be interested in seeing the result when using a statue with a minimum of three levels of contact – approximating the three levels of the body in the Shroud (top hand, bottom hand, lower trunk). Spatulas and coins are a good start but an object with more detailed 3D would be very helpful.

My response:

David Goulet :
If anyone is doing another heated statue experiment, I’d be interested in seeing the result when using a statue with a minimum of three levels of contact – approximating the three levels of the body in the Shroud (top hand, bottom hand, lower trunk). Spatulas and coins are a good start but an object with more detailed 3D would be very helpful.

It’s almost a year since I bought an item at a street market in the south of France that would seem to fit the bill.

antibes-market-wall-crucifix-manual-correct2

I’d almost forgotten about it. Now then, let’s see if I have any linen left (or will cheaper cotton do for starters if concerned for now with macroscopic aspects only?). But who’ll be first to accuse me of being sacrilegious? To which the answer is: we’re only dealing with a lump of cast metal.

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Update: I’ve reported the results of this morning’s first experiment with that brass template in the picture above on the same original posting. Here’s the link. I’ll import some more pictures here later today, and maybe think about doing a separate posting, given the amazingly good results (well, I think so anyway   😉

 

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About Colin Berry

Retired science bod, previous research interests: phototherapy of neonatal jaundice, membrane influences on microsomal UDP-glucuronyltransferase, defective bilirubin and xenobiotic conjugation and hepatic excretion, dietary fibre and resistant starch.
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