#! /usr/bin/python3

import sys, re
import html_gen as h
from process_funcs import bash
import html_report_funcs as hr

last_edit = "Last edited on 2025-10-29 15:43:41 by stolfi"

def main():

  global last_edit
  
  thumb_width = 80*???text_width/100 # Width for image thumbnails.

  title = "On the nature of the VMS ink"
  st = h.new_doc(title, "#eeffdd")
  
  h.section(st, 2, "Summary")
    
  h.parags(st, """???""")
  
  h.parags(st, """The VMS ink cannot be iron-gall ink. Not even expired
  iron-gall ink, or "low-iron iron-gall ink".It would be nice to know
  its real composition. For now we can only speculate""")
  
  h.section(st, 2, "Nature of VMS ink")

  h.parags(st, """ As one can see in that image, its color behaves in a manner
    characteristic of soluble ink dyes: as it gets thicker, the hue changes,
    and eventually becomes black, whatever its original color. This behavior
    is a consequence of how they get their color: light goes through the
    ink, scatters off the background surface (paper etc) and goes through
    the ink again. The amount of light that gets absorbed by a layer of ink
    of some unit thickness is some function T(f) of the wavelength f. The
    shape of the function T (the transmittance spectrum) determines the
    ink's color. The paper may absorb some light too; the fraction P(f) that
    it scatters is its reflectance spectrum, which defines its color (P(f) =
    1 at any f for white paper). For an ink layer of general thickness x,
    applied over paper, the fraction of light that comes back out is T(f)
    raised to the power 2x times P(f). Since T(f) is always less than 1, as
    x increases the result tends to zero, irrespective of the ink and paper
    color.

    Suspension inks are another type of ink that is rather distinct from
    soluble dye ones. They consist of finely powdered insoluble opaque solid
    (a pigment) suspended in a binder such as gum arabic glue. The particles
    are held onto the surface of the paper only by the binder, and thus
    these inks are not usually waterproof and can be rubbed off. The
    particles have a fixed reflectance spectrum R(f) that determines the
    pigment's color. When the ink is applied over paper in a relatively thin
    layer, some of the light will be scattered by the particles, some will
    pass between them and will be scattered by the paper. The overall color
    will be y R(f) + (1-y) P(f), where y is the fraction of the area that is
    covered by the particles. At low y (diluted ink) the effect will be
    similar to that of diluted dye ink. However, as the ink gets thicker,
    the fraction y eventually becomes 1. At that point the inked surface
    will have reflectance R(f), and making the ink layer thicker will have
    no effect. Tempera and oil paints are intended to be used with full
    coverage (y = 1). Watercolors are meant to be used with coverage varying
    all the way between 0 and 1.

    Iron-gall ink is a third class of ink, which may be called mordant inks.
    It is made by mixing a source of tannin with green vitriol (iron II
    sulfate) Tannin molecules have many flexible arms that will stick to
    protein molecules in general, thus binding them together. It is the
    substance that "ties up the mouth" when we eat an unripe banana. It
  hampers digestion of food by binding to digestive enzymes. Plants make
    it as a defense against predators in general.

    When solutions of tannin and iron(II) sulfate are mixed, some arms of
    the tannin molecule will wrap around the iron ions. This iron-tannin
    complex remains soluble for a while. If it is applied to vellum, it will
    infiltrate it and then the tannins will stick to the proteins in the
    leather, thus binding the iron to the vellum. Soon the iron(II) ions
    will oxidize to iron(III) and the complex will become a deep blue-black;
    at the same time the complexes will bind to each other through the iron
    atoms, with will help make the ink waterproof. This last process will
  happen also when the liquid ink exposed to air, causing the complex to
    precipitate out of solution rendering the ink useless. Even if stirred,
    this spoiled ink will be a mere suspension ink, neither waterproof nor
    rubbing-proof.

    Well-prepared iron-gall ink works well only on surfaces with proteins,
    such as vellum and parchment. It will soak into the fibers of paper but
    will not chemically bind to the cellulose. Still, it was commonly used
    on paper too because it was available, and was a nice purple-black when
    dry. It was not quite waterproof, but the paper wasn't either, so that
    did not matter.

  however, iron-gall ink is like the first Ford Model T: it can be any of
    color, as long as it is black. So, colored ink, like the red one used on
    f67r2, is definitely not iron-gall.

    And here comes the big question: is the "normal" VMs ink, used for
    practically all the text and figure outlines, iron-gall ink, or
    something else?

    (I can hear you scream "X-ray fluorescence", but that test is not as
    conclusive as it is assumed to be. Let me leave it at that...)""")

  h.parags(st, """[LISA:] The
    point about the Marci annotations is that they have NO iron AT ALL. Only
    zinc and a few other trace elements. 
    [STOLFI:] 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?""")
    
  h.parags(st, """Iron gall ink is relatively light bluish-gray and water-soluble when applied
    but darkens and becomes an insoluble polymer soon after application.  At the same time
    it binds chemically to parchment so the writing becomes waterproof.  These processes
    are quite fast (hours or days, not years).
    
    If the ink has an excess of iron it may become insoluble as prepared and then
    the above wouldnot apply.""")

  # hr.clip_fig_parag(st, "f102v1 stain")
  # hr.clip_fig_parag(st, "f103r stain")

  h.parags(st, """Another interesting case is f102v1 and f103r. There is a big orange
    stain near the top right corner of the latter, that ofsetted on f102v1.
    After profound analysis of the images, I concluded that the offending
    substance was ketchup. OK, OK, I mean, some reddish sauce that had small
    bits of a very thin dark red membrane. Probably a goulash-like sauce
    with bits of bell pepper skin.

    On f103r, the stain fell over the text; and the sauce (or, more likely,
    the mopping up of it) severely effaced the text. (Incidentally, the
    state of that area is one of the best pieces of evidence for the
    Restoration Hypothesis. And for the claim that the Restorer could not read
    the text and had no access to the Author)

    On f102v1, the stain fell mostly on the figures of two plants. There, it
  had a similar erasing effect not only on the outlines of the plants, but
    also on the painted areas (a green leaf from the plant on the left, and
    one of two blue ... duh ... leaves of the plant at right.

    Thus I think that we can confidently say that the ketchup goulash spill
  happened after the painting.

  however, I see no trace of offsetting of the paint from f102v1 onto
    f103r, even though the paint was obviously softened by the sauce. Maybe
    my pareidolia is not that good after all. Or maybe any paint that did
    offset onto f103r was promptly wiped off together with the sauce.""")
    
  h.output_doc(st, sys.stdout, 99, last_edit)
  return 0
  # ----------------------------------------------------------------------

main()