From: mcgrath@cs.uiuc.edu (Robert McGrath)
Subject: Re: Shroud exposed at early date (Tim O'Neill)
Reply-To: mcgrath@cs.uiuc.edu
Organization: University of Illinois, Dept of Computer Science
Date: Thu, 3 Sep 1992 16:56:31 GMT

In article <LEET.92Sep1095317@dove.ims.com>, leet@ims.com (Lee Thomas) writes 
in part:
|> >>>>> On Thu, 27 Aug 1992 02:06:03 GMT, Tim.ONeill@english.utas.edu.au (Tim O'Neill) said:
|> 
|> Heller gives the following results to show that the "blood" is
|> really blood (his primary involvement in the project):
|>     1. High iron in blood areas by X-ray fluorescence
|>     2. Indicative reflection spectra
|>     3. Indicative microspectrophotometric transmission spectra
|>     4. Chemical generation of characteristic porphyrin fluorescence
|>     5. Positive hemochromogen tests
|>     6. Positive cyanomethemoglobin tests
|>     7. Positive detection of bile pigments
|>     8. Positive demonstration of protein
|>     9. Positive indication of albumin
|>    10. Protease tests, leaving no residue
|>    11. Positive immunological test for human albumin
|>    12. Microscopic appearance as compared with appropriate controls
|>    13. Forensic judgement of the appearance of the various wound and
|>          blood marks.
|> All this is to blow away McCrone's contention that the red stuff is paint.
Only if you accept Heller's claims.  And knowing McCrone's reputation,
I'm not sure I would take Heller over McCrone just because you say so.   

It is not clear to me that these findings do anything at all to show that 
the image is not made of paint.  Even if the findings are correct (which 
I reserve judgement about considering the record) and even if the 
interpretation is correct (whcih I reserve judgement about), this shows 
that there once was some blood on the shroud.  That hardly invalidates the 
finding that the image was made of paint, does it?

|> Heller notes that any painting must have been done without the help of
|> an organic substrate, since the fire scorch caused no discoloration of
|> the image.  Also, the image appears only in the topmost microfibrils
|> of the cloth, and there is no capillarity or matting (as there is in
|> the bloodstain areas).  Hence, the paint-or-whatever never soaked into
|> the actual threads - pretty tricky.  Additionally, no directionality
|> can be detected in the image, so brushstrokes were not used (maybe a
|> roller? :-).
You seem to know a lot more about very old painted images on cloth
than I do.  My understanding is that the current appearance of the
shroud is what is left after most of the paint has fallen off, and
looks pretty much like old linen with the paint fallen off is supposed
to look.  I'm not sure what "organic substrate" means exactly, but
if you mean egg-based tempura paints then you may well be correct.
As to the "directionality", note that what you see is only the
tiniest remnants of the paint, so I'm not sure what "brush marks"
would be visible.  Anyway, since my leading theory is that the
image was a rubbing, I wouldn't expect many brush marks anyway.

|> I wish more skeptics would quit trying to shove eagles
|> into pigeon-holes.
You're the one who see's an eagle where there is nothing more than
a mangey pigeon and a lot of wishful thinking.  All the "science"
in the world can't make the anything more than a not particularly
well preserved medieval artifact.
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