Inks and pigments

The McCrone report is online, available through the Beinecke site as a pdf. Since it is publicly available, I hope it will be alright to extract the relevant sections.

The point here is that the number of samples which could be tested were relatively small, and so the report does not give an impression of the same range that was in Dr. Carter’s description (quoted by d’Imperio, as in my earlier post).

The first thing to note is that in the summary, the report says that “the binding medium for all the inks and the green paint is gum.”(p.6)

One red-brown paint is mentioned:

The red-brown paint was identified as ochre by PLM and EDS in the SEM. XRD [X-ray diffraction – a means to get more specific information] characterized the crystal phases present as consisting of hematite, iron sulfide, possibly minor amounts of lead sulfide, and palmierite (a lead-potassium-sulfide  compound) in, most likely, a gum medium.

That’s what I meant by vague.  With so few samples that could be taken – and with rare manuscripts one cannot expect more – it is almost inevitable that the data must include some uncertainties and statistical ‘noise’.  Reporting that accurately means having to say such things as that the medium is ‘most likely’ gum or that there are  ‘possibly minor amounts of..’  this substance or that.

Such a degree of uncertainty is unavoidable but the fact is that it should prevent readers from making overly categorical statements about just where the manuscript might have been manufactured.

In addition, the limited number of samples leaves the composition of the other colours  and tones  (as listed by Carter) unknown, or at least uncertain.

Similarly, a scientific report’s including caveats is necessary, and these occur in the account given of a/’the’  green pigment. Whichever the particular green it was  among the considerable number which Carter lists, McCrone’s covering letter says, in  essence, no more than the one tested was some derivative from copper or copper ore.

In repeating the following, I have added italics to McCrone’s caveats and qualifications,  simply because it can be too easy otherwise for a reader to ignore them, and so place a greater weight on a scientist’s tentative suggestion than was intended.

So:

Green –

the (sic) green paint was tentatively identified as a copper and copper-chlorine resinate, most likely produced as a salted copper corrosion product.

PLM indicated .. green-stained transparent material consistent with copper resinate and smaller amounts of anisotropic green particles. The presence of chlorine in the EDS spectrum suggests that the crystalline material might be atacamite or other copper-chlorine compound.

In all cases, the amount of copper is in significant excess to that of chlorine and something like a copper resinate, that is a copper-containing amorphous resinous organic material, is likely.  Xray diffraction of the sample produced no pattern whatever, strongly suggesting that the bulk  of the material is non-crystalline.

Producing copper resinate was a cottage industry in medieval France, and doubtless elsewhere.

In scientific terms, a ‘strong suggestion’ in the foregoing paragraph usually means that the scientist is pretty sure. But the description  ‘amorphous resinous organic material’ doesn’t necessarily mean a resin of vegetable origin.  It would also describe shellac, for example, which comes from insects just as the red pigment kermes did.

If there were certainty that the crystalline material were atacamite (the report says only that it might be) it would have given some  idea of the sort of conditions under which the manuscript might have been inscribed, because atacamite requires an arid environment to form; in effect it is a product of slow and therefore usually natural desiccation within a consistently moisture-free environment.   But the report was unable to be so specific on the point, and it would have been improper to be more specific that the results warranted.

Nonetheless, we know only that  the particular green tested was ‘something like’ a copper resinate in some amorphous resin – animal or vegetable – though not mopa-mopa.

I won’t quote more of the covering letter.

But I thought it fair to make clear why I described the report as vague, and that I should  emphasise as I did not in the earlier posts that such vagueness is due partly to the limited number of samples which could be taken, and partly to a need to  report data accurately, including the uncertainties.

Of all those other colours and shades listed by Carter, some could simply be thinner, or thicker, versions of those tested but the report does not tell us so, and since they were not tested, cannot tell us so.

I have now been referred to a YouTube video in which the statement is made that “all the pigments are mineral pigments”.

Since it is a YouTube video from a television presentation, I do not know how that statement was cut in, nor if the sentence refers to the  same report: whether it means ‘all those tested were mineral pigments’.  It may also have been a personal opinion, or reflect another assessment of the manuscript which I have overlooked.

I should also correct an error in the same post – concerning the use of minerals in dyeing.

Ferruginous (iron-) clays have long been used to yield shades of red (from hematite) and yellow ochre (limonite).

Hematite is the principal iron ore and an element in many pigments, including those in the manuscript.

At  the end of the post is shown one our earliest remaining examples of dyed silks. It comes from inner Asia and was dyed using textile leggings Antinoe coptic style weaving Louvrecinnabar. (The region where it was found now lies within   China’s territories, but  the ethnicity of the makers is not determined, even if the textile is often described as  ‘Chinese’ :  designs like this more often appear to the south and through the near east).

Azurite: I have been further corrected about azurite, which I had never encountered before as dye, but only as a paint or pigment. I have been told that azurite was used to ‘colour fabric’ from before the Mediterranean’s classical era. I note the information now, but will need to get further details, especially in regard to the textiles from Antinoë, which I had intended to mention when discussing the history of the ‘standing archer’ type in the middle east. I add a picture of one piece discovered there; the original is now in the Louvre.

My sincere thanks to the people who commented; it is less embarrassing to have faults noted than to be guilty of misleading others even in good faith.

China cinnabar dyed fabric

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