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Jorge_Stolfi · 29-09-2025, 10:19 PM

(29-09-2025, 09:20 PM)LisaFaginDavis wrote: You are not allowed to view links. Register or Login to view.The point about the Marci annotations is that they have NO iron AT ALL. Only zinc and a few other trace elements.

Ak, OK. In other words, it is not iron-gall ink (IGI). Probably India (China, lampblack) ink or the like.

Iron-gall ink makes sense in only two situations:

Someone wanted to write something on vellum or parchment, and wanted it to last for many decades, even in damp environments and/or under frequent handling of the document; or
Someone wanted to write something in ink, and had some IGI at hand already.

Apart from case 2, for writing on paper IGI should be slightly worse than India ink, pencil, or other media.

Even for writing on vellum or parchment, there would be no point in using IGI for temporary annotations -- like quire numbers to guide the book-binder, or a tentative letter substitution table on the margin of a presumed cipher book. In fact, if the annotation was meant to be erased later, it had better not be in IGI.

Marci's secretary presumably had IGI at hand at all times, to write permanent stuff on vellum. Marci himself may have written only on paper, and then he would have no reason to make and keep IGI.

By the way, AFAIK labs like McCrone have no way to positively identify iron-gall ink. X-ray fluorescence (XRF) only reveals the metallic elements present in the sample, not their chemical state. X-ray diffraction can identify crystalline minerals like azurite or rutile. But IGI is not crystalline, and other than iron it does not contain anything distinctive. (Tannin, the component from galls, is used in tanning the vellum; so, even if it could be detected, that would not mean anything.)

So I suppose that those labs "identify" IGI only by exclusion:

If there are "modern" pigments like rutile or prussian blue, it is a forgery; else
If there are known crystalline minerals like azurite, it is "paint from the period"; else
If there is iron, it must be iron-gall ink; else
If there is no iron, then... duh... it must be "iron-free iron-gall ink".

The honest thing to say would be "it is unidentified dark ink that contains iron" or "it is unidentified dark ink that does not contain iron". But that would not look good on the report, would it?

All the best, --jorge