Friday, June 27, 2014

First test of the quicklime hypothesis (Turin Shroud image) - in pictures

For background, see the posting that immediately precedes this one.

I'm restricting this post to pictures only - maybe with a caption or two. I need time to explore some more, and get thoughts together.








Oops. Underside of the polythene container is melting.





Let's try earthenware instead, and skip the temperature monitoring. Just tip quicklime onto linen and cotton, add water, and see what happens.


Do I see thermochemical scorches (no applied heat - just a chemical reaction between quicklime and water)?

Yup, scorches alright. Cotton on left. Linen on right.  Oh, and that's the knackered container from the abandoned experiment. But why are the scorches so localised? That's the question being asked in the next experiments.


Other postings in the pipeline: response to questions raised on shroudstory.com (Piero and daveB); does the TS man really have a beard and moustache?

Afterthought. there's a related thermochemical system that is maybe worth some consideration. It's the setting of Plaster of Paris (calcium sulphate hemihydrate, 2CaSO4.H20) when mixed with water to form the dihydrate., CaSO4.2H2O.  The reaction is admittedly not as exothermic as that between quicklime and water, and its questionable whether it would ever get hot enough to scorch simple linen (treated linen is another matter). But there's a big advantage in the context of the TS: one could create a mould from a living (or dead) person using death mask technology, the subject of a previous posting on my WordPress site, and use that to make a 3D replica with a slurry of Plaster of Paris. Might there be sufficient heat thrown off when the plaster fully sets to leave some kind of imprint or image on a sheet of linen thrown over the top?  You read it here first (probably last as well).


Update: Sunday 29 June
 
It's said that one picture is worth a thousand words. On that basis, the blog posting so far should be worth 8 thousand words. Yet nothing could be further from the truth. To convey the truth where quicklime and its possible relevance (or lack thereof) to the Shroud of Turin is concerned, I would need a lot of words, maybe not 8000, but a lot. Why? Because I have (deliberately) committed the cardinal sin in science reporting by being highly selective so far in what I have chosen to report. Thus far, anyone looking at the pictures might think to themselves  "Wow, that's a lot of heat coming from that reaction between quicklime and water- so much so that plastic pots are melting, linen is being scorched. OK, so there's no image as yet, the starter experiment not being set up to produce an image, but the system clearly has great potential."

No it doesn't. It's actually of exceedingly limited potential. That I know already, not just from the highly localised nature of the scorching (reported) but from events (notably up-and-down thermometer readings) that preceded the spectacular meltdown of the plastic container.

Nope, I haven't been dishonest, just selective in the nature of my reporting, and later in the day I shall start to fill in the gaps, using up my quota of 8000 words to describe the profound limitations of the quicklime model, and why already I suspect it to be non-starter. It's to do primarily with the two physical states of water in this system (liquid or gaseous, hint hint).

I see my little punt has been flagged up on shroudstory.com. No comments as yet, which is perhaps just as well. I'll now do the decent thing and copy and paste what I've just added here.

Moral: beware selective attention to particular details, indeed selective reporting in general. Trouble is, you don't know when it's being done (but with long exposure to gee-whizz press announcements etc one can develop a nose for it. Indeed, it was that "nose" that 'attracted' this science bod into shroudology some 30 months ago. The amount of selective reporting that goes on in shroudology is nobody's business (except mine - see blog credo above).

Back again .

OK, now for some of those details that were omitted from the preliminary account, basically because I was puzzled and needed time to ponder.

The experiment began by adding water one drop at a time through a hole in the lid (just visible in my pictures). I had expected an immediate response on the thermometer, but that was not to be. There was a lag, and several more drops were needed to start a sluggish rise in temperature. The needle would rise a bit, then stop, and start to fall back. That was the signal to add more water, but there was a downside - the temperature then initially fellback a bit, and one had to wait a while for the 'new' water to react with the quicklime, as indicated finally by a new upward surge in temperature. But I then found I was having to add water not just 1 drop at a time, but an entire dropping-bottle full, simply to keep the temperature rising (but still with that annoying yo-yo effect).

Things were looking hopeful when the temperature reached some 80 degrees Celsius and higher, but that's when the bottom of the reaction vessel began to melt  (below the thermometer probe)  dropping its contents onto the garage floor (just as well I didn't try the experiment in the house).

So why was there not a smooth and continuous rise in temperature, and why were the scorches in the second quickie experiment so localised?

Here's my explanation: water is needed to start the reaction, and the heat of reaction quickly changes some or all of that water into steam. However, not only does each new addition of water 'undo' some of the previous temperature rise through the new water being cold,  but there is another effect operating due to the high latent heat of vaporisation of water. For as long as there is liquid water present, it will boil at 100 degrees C (maybe a little higher due to soluble calcium products) and prevent the temperature rising above 100 degrees C.

So how were the scorches produced, given that temperatures approaching 200 degrees and higher are needed in conventional hot metal experiments to produce scorching? I suspect that there is a brief 'wndow of opportunity' in pockets of quicklime in and around the linen that allows scorching when the last of the liquid water has been vaporised, but there is still "water" avalailable. But the latter would be gaseous water, probably superheated steam.

The equation for the slaking of lime is conventionally written with reactants and products in their standard states at 15 degrees C (298 degrees K), with the symbols s, l and g used to indicate those states.

CaO(s)  +  H2O(l) =   Ca(OH)2 (s)

But to see scorching, I believe the relevant equation is:

CaO(s) + H2O(g)  = Ca(OH)2 (s)

(It's testable, needless to say, e.g. by placing quicklime/linen in the steam above boiling water, and expecting to see more even scorching  In fact, I've just done that experiment, enclosing some quicklime in a linen pouch and suspending it over steam from a boiling water in a saucepan. The quicklime becomes slaked, judging by inertness towards water when the pouch is later reopened. I had hoped the linen would scorch, but that was not to be. Maybe the steam carries away excess heat, preventing the temperature rising sufficiently to scorch linen.)

But there one sees the practical pitfall of the mechanism proposed - namely that one is slaking the lime with liquid water, not gaseous water, i.e. steam. So it's only spasmodically and in localized 'hotspots' that the temperature is able to get much above 100 degrees C.

That makes the system almost impossible to design and manage predictably.

New addition: 19:10 Sunday June  29

And finally (for now, at any rate) here are my belated responses to a question  raised by a  commentator on shroudstory.com in response to my first quicklime posting.  (It should probably go on the post before this one since that was the one they were responding to, but it's overlong already).

Here's the comment from daveB of Wellington, NZ, divided into points (my responses in blue):


  
daveb of wellington nz
June 21, 2014 at 5:16 am

Read your posting, saw the video, all quite clear. You’re going to have to do some experiments, and probably several reruns before you strike any gold. Obvious questions arise: 1) Image is said to be superficial, maybe resident only on impurities layer; Can such an imaging process be so superficial? Or will it penetrate the fibres (flax medullas on TS not affected by process!)

I know of no hard evidence that the image is on a man-made superficial layer, e.g. starch or saponins etc (based on citations from the Pliny!).  It all seems highly conjectural to me. The behaviour of the sticky tape samples under the microscope when fibres are pulled out (leaving those allegedly sub 200nm ghosts) is open to different interpretations, and in any case there is a big risk of artefacts when viewing whole fibres, especially when immersed in an adhesive hydrocarbon.
The PCW is reckoned to be 200nm thickness plus or minus. Why was that not considered first before invoking an impurity coating?


2) Do we know whether or not there’ll be an alkali corrosive effect on the CaO side of the linen?

Alkali is a standard treatment for cotton (mercerising). It changes the physical structure of the fibres. It also makes cotton more resistant to scorching, according to some experiments I did a while back, with less effect of linen.. Quite why that should be so I cannot say. It’s tempting to think there are differences in the PCW, but one cannot discount the possibility that modern fabrics have coatings that are more or less resistant to scorching, and that alkali acts on those. Suffice it so say that any effects one sees with quicklime have to be interpreted with caution on account of calcium hydroxide being a fairly strong alkali ( as anyone who has handled wet cement will know to their cost).


3) What would be the signature residues of CaO on the backside of the linen, any? No one’s noticed any such residue signature so far.

It’s been a while since I looked at the mineral analysis of the TS, and I’ve mislaid the references. I seem to recall that there were substantial amounts of calcium (as CaCO3?) on the TS, but stand to be corrected.


4) Process will necessary take some finite time, so perhaps a heat process would affect subject and its appearance with consequent distorted image on cloth, but no such distortion appears on TSM (no “corruption” evident).

Yes, quicklime is a desiccant, so any model that envisages a long-term process might need to explain why the TS image is not excessively  skeletal in appearance (while noting the boniness of fingers).

 5) Maybe it’s not a scorch but something else, so that you could still be on to something.

A “scorch” to me is simply a discoloration due to chemical modification of linen components, primarily carbohydrates, but not excluding lignin. It may be the result of thermal processes that require no added substances, but the latter are possible, provided they leave nothing substantial behind that would conflict with the STURP finding (claim?) that there are no pigments etc that would suggest the TS was some kind of painting.

Even if one envisaged an “invisible ink” effect, produced with say lemon juice, leaving minimal residue that escape normal chemical tests for unusual chromophores, etc., then heat is still needed to produce the scorched look (which incidentally can be seen with lemon juice alone, needing nothing else present).  So in a sense it’s still a “scorch” albeit not a pure thermal effect with or without  chemically assistance.

 6) It might not be quicklime, but it could still be alkali from body products or even Max’s red-heifer ash.

Yes, he used to refer to limestone and red heifer ash as sources of alkali. That’s not true re limestone. While limestone (calcium carbonate, CaCO3) is capable of neutralising acids, it has scarcely any effect on the pH  of pure (CO2-free) water, and does not fit the definition of alkali as a soluble base, since bases are defined as reacting with acid to make a salt and water only (carbonates make CO2 as well). Animal ash? Yes, it may be an alkali, though that’s as likely as not to be due to accompanying wood ash – a good source of potash , i.e. potassium carbonate, that accompanies the animal bones. Contrast with calcium hydroxide from the slaking of quicklime, which as we’re agreed,  has powerful alkali properties that fit all the chemical definitions relating to base character,  solubility and ability to produce a big increase in pH (typically above 11 or 12).


 7) You’re looking for lots of heat, but if only impurities layer is affected, maybe you don’t need the same heat as is necessary to scorch linen (image is said to be resident only on crowns of fibres).

Yes, it’s a lot harder to explain selective scorching of the fibre crowns in  chemical or even thermochemical systems, although Rogers as we know attempted to do so with his arguments based on capillary action. Indeed, it is the predominant (though not exclusive) location on the crowns that makes pure thermal scorching by contact with an applied template the most realistic model in my view.

I recall someone’s ribald comment a year or two back, that you’ll end up proving the Resurrection! You still have to end up with an image that looks like crucified Jesus, complete with crucifixion marks, scourge marks, bleeding head, and lanced chest wound. Don’t think they did that sort of thing in medieval times, more into hanging, drawing and quartering! Look forward to seeing pictures of your chicken legs! Hope the family cat survives!

Yes, but you don’t know that the image we see today was formed all in one single event. Indeed, if you look at the Lier copy, it has L-shaped poker holes and nominal blood stains (yes, I’m aware of the cop-out argument based on contemporaneous viewers' sensibilities etc, but it’s evidence for authenticity we are seeking, not explanations for why that evidence is all too often less than convincing).

Hanging, drawing, quartering certainly. But aren’t you forgetting something else (burning at the stake). Where’s the evidence, say, on the Lirey badge that the figure depicted was (a) Jesus (b) crucified. I see little if any. Who’s to say it was not (a) Jacques de Molay  (b) burned at the stake – slowly?  Posture, non Christ-like appearance and some other details would seem to favour the second of those hypotheses.
Yes, I am doing something  like a chicken leg experiment (with a pork sausage – all I  had to hand, and now on its, er, third day). Disappointing result. No scorching – insufficient water presumably.



3 comments:

Hugh Farey said...

Epic! Two other thoughts. Firstly, the rehydration of anhydrous magnesoium sulphate is reckoned quite a dangerous procedure because of the heat given out, and also, since you mentioned plaster of Paris, a little while ago a girl lost all the skin off her hand when she somewhat foolishly decided to make a mould of it, and it set solid during an Art class. Science teachers get told of this sort of school related epxerimental accident via one of our memberships.

sciencebod said...

Thanks for the observations Hugh. Epic? Maybe, but there's a lot more to be done before thermochemical reactions can be implicated in the TS. Still, it's another angle to investigate, and gets away from the recycling of stale debates (you know what).

It's CaSO4, rather than MgSO4 that gives the exothermic reaction (or maybe we've been misinformed about why Epsom Salts go through like a dose of the proverbial).

That poor girl lost more than her skin. Look at a horrific graphic towards the end of a posting I did a while ago.

http://shroudofturinwithoutallthehype.wordpress.com/2012/08/26/is-the-man-on-the-turin-shroud-a-pseudo-negative-imprint-from-a-death-mask-could-that-be-why-the-modern-day-photographic-negative-looks-so-much-better-than-the-original/

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