VMs: Re: Re: Inks and retouching

["GC" <gc-@xxxxxxxxxxxxx>]

Jorge,

Excellent response.  Let me go through and follow the threads in a later
reply.

A quick clarification on the paint - if you use a watercolor paint on thin
vellum, like any other leather the moisture will dampen the opposite surface
if enough is applied, but the pigment will not seep through, unless it is a
dye solution instead of a particulate watercolor. It's the damp I'm
concerned with, not the actual 'bleed-through'.  I suggest this is why we
see increased adherance 'at or near' the edges of the reverse image.   I'm
saying that the way this dampness affects the text is consummate proof that
the paint was applied *after* the drawings were done and the text written.
We appear to be in agreement on this.  How soon after is an unknown, and how
damp the other side got is highly dependent on the amount of water to
pigment.  Cracked pigment might indicate less water and more pigment, hence
a thicker application, less moisture reaching the verso, as an example.

More later.

GC

----- Original Message ----- 
From: "Jorge Stolfi" <stolfi@xxxxxxxxxxxxx>
To: <vms-list@xxxxxxxxxxx>
Sent: Saturday, July 31, 2004 7:16 AM
Subject: VMs: Re: Inks and retouching


>
> Glen writes
>
>   > [Glen:] While there is an indelible quality to the ink, the darker
>   > portions remaining appear to be a component that is very sensitive
>   > to moisture. Some time ago I examined this phenomenon on color
>   > jpegs, and reached the conclusion that the two portions of the ink
>   > in question did not mix well together. The indelible portion
>   > appears to be an organic non-soluble, possibly an organic oil or
>   > acid of some sort, capable of etching the vellum. I'm not up on my
>   > ink chemistry, so the exact chemical nature of the indelible
>   > compound is an assumption. The dark portion(s) in question appear
>   > to be water soluble.
>
>
> The assumption that the ink color is due to a mixture of two or more
> colored components, some of them soluble and some not, is quite
> reasonable. It does make color analysis more complicated (especially
> without those calibration strips...).
>
> However, I do not think that the color variations can be explained by
> the *soluble* component being lost. On most pages there is no evidence
> of water damage, or even moisture-induced smearing. Except for a few
> isolated cases where the water stains are themselves quite visible, I
> believe that the only viable explanations for ink fading are (a)
> mechanical wear or (b) chemical aging of the pigment/dyes themselves.
>
>   > The two together have separate absorption properties, and I
>   > wouldn't be surprised to find that most "retouching" evidence is
>   > caused by this dual-based ink and the effects of age on the two. I
>   > still stand by this conclusion.
>
> I grant that some of the dark/light variation is probably due to
> mecanical ink flow effects and differential wear/fading. However there
> are many, many places where that explanation does not seem to work.
>
> It is pretty obvious that the EVA "iin" (your "m") on f1r was
> retraced, and there are many similar examples all over the manuscript.
>
> Those retracings may have been done (A) by the author himself, as he
> was writing -- e.g. when the pen went dry halfway through a character.
> Or (B) by the author, at a much later date, to restore text that had
> faded over time; or (C) by a later owner, for the same reason.
>
> There are indeed many examples of (A); I have been just staring at
> seveal of those on f81v (top left). In these examples the under-ink is
> clearly the same color as the retracing ink, only fainter, and is
> clearly the end of an inking.  In fact, I have looked through most
> of the biological pages, and the only retracings that I can see
> on the text are of this type. (The drawings may be a diferent story,
> but I am not ready to make guesses on them yet.)
>
> However, there are many examples elsewhere that cannot be explained
> as (A). That covers most of the dark traces in f56v and in the
> Zodiac section. There the "old" and "new" inks are too consistently
> different, the "old" text is uniformly fainter, and the retracing
> seems to be consistently confined to certain parts -- such as
> labels in a certain band, or on a certain half of a circle;
> or all those right breasts.  Moreover the retracing there clearly
> seems to have been the work of someone who did not understand
> the drawings --- see the moustache on f56v, the nymph legs on the zodiac,
> etc. --- which seems to exclude (B) as well as (A).
>
>   > If you remember in an earlier email I asked why the dark ink tends
>   > to run in "veins"?
>
> First, a note of caution: beware that the human eye has a tendency to
> see lines in images that contain only random noise. Remember Powell's
> Martian Canals? For instance, when staring at the highly magnified
> images, I see all sort of drawings and characters in the blank vellum.
> I mostly learned to ignore them, but sometimes they seem so compelling...
>
> So the "veins" may be real, or may be an illusion. But I grant that
> the dark ink is often concentrated in certain areas of the page. Those
> may be simply raised spots on the vellum surface, which rubbed against
> other pages or the table, and hence had more wear. This wear is quite
> visible on sharp creases, and the vellum surface is likely to have
> less conspicuous waves (say 1mm high and 1 cm wide) which would not be
> visible on the images but would wear a lot more than the nearby
> throughs.
>
> Note that this explanation fits with (B) or (C) but not with (A),
> since those gentle waves should not have made much difference
> while the text was beeing written.
>
>   > Let's take f3v as demonstration that my theory
>   > has basis in observable fact. There's more than one mechanical (or
>   > chemical) effect observable on this folio, but right now I'm only
>   > interested in one. Here we see the image of the paint from f3r,
>   > and notice that the moisture from the paint on the other side of
>   > the folio causes some of the soluble portion of the ink to adhere
>   > better, causing the ink to appear darker.
>
> Are you saying that one side was written after the other side had been
> painted, and while the paint was still moist? It seems highly unlikely.
>
> Moreover, vellum (unlike paper) seems to be mostly impermeable. The
> "bleedthrough" effects that we see are largely due to it being
> slightly transparent, especially where a little dent on one side
> matches a little dent on the other side. (Ever wondered why "vellum
> paper" got that name?)
>
> I haven't looked for them, but I bet that there are few if any
> instances where the ink actually flowed across the vellum. Certainly
> no such "material" bleedthrough is visible on f3r, for example. In any
> case, there doesn't seem to be any correlation between the "retraced"
> characters and bleedthrough.
>   > We see many dark portions on the edges of the painted image, and
>   > in a few places we see a glyph split between the painted image and
>   > regular vellum, where the portion of the glyph inside the painted
>   > image is dark, but that outside is faded. f3r, line 5, the <ch> in
>   > word 2. ...
>
> The green bleedthrough does indeed make the characters written over it
> look a bit darker. This is an expected optical effect and does not
> need to involve any moisture transfer.
>
> One interesting detail on page f3r (a page which I had not yet
> looked at in high-res) is the cracked green paint, on the bottom
> right leaf. Note that even though this area was positively
> flooded with paint, it did not cause any more bleedthrough
> than other places where the green paint was applied with an
> almost dry brush.
>
> Another interesting detail is the way this green paint darkens with
> increasing thickness. I don't know, but we may be looking at a green
> dye rather than a green opaque pigment. (The text ink on this page too
> looks transparent.) I wish I had looked at this page yesterday: I just
> spent many hours trying to separate the green ink on page f81v
> (biological section), and was frustrated -- that too seems to be a
> transparent dye.
>
> If it is indeed a transparent dye, I have no idea of what substance it
> could be. It may be much later than 16th century, perhaps 19th or 20th
> century. A student at the Collegio Romano, perhaps?
>
> I am well aware of this effect and I *do not* count those slightly
> darkened characters over bleedthroughs as retracing evidence, not even
> as "suspects". On the very first word of f3r (EVA "tsheos"), I would
> say that the final EVA "s" is of the same color as the legs of the
> initial "t", except for the effect of darker background.
>
> On the other hand, there are many cases of a single character or
> stroke being much darker than its neighbors, with all of them are over
> the bleedthrough, or all of them are outside it. The "o" on that
> same word is an example.
>
> Incidentally the darkening of the strokes over the bleedthrough
> may allow us to decide whether the brown ink is transparent dye
> or opaque pigment.  In both cases we would expect a darkening,
> but the numerical effects on each channel should be different.
>
> Most of the darker letters on f3v are what I would call "suspects"
> only, not evidence. The ink seems to be the same, and the "hand" too.
> So indeed they may well be instances of (A) above. E.g., after the
> author finished writing a paragraph, he went over it again and
> reinforced those letters which had come out too faint on the first
> pass -- paying special attention to those which are likely
> to be confused, like "o" and "a"s, "r"s and "s"s.
>
> There is marginal evidence of retracing is on the first "tsheos".
> Note that the horizontal stroke of the "t" does not connect to
> the left eye. Note that the plume is much fainter than any text
> around it; so it it was added later ("crossing the sh's") it must
> have been much after the end of that word.
>
> The first word of line 6 ("ychtaiin") also has a marginal evidence:
> a bit of light ink sticking out of the right foot.  A small bit,
> but note that the pen was obviously quite loaded, whreas the
> "old" stroke seems to have been done by a very dry nib.
>
> Other similar bits are seen on paragraph 2: at the very bottom of the
> first "s" in "sols" (line 1, word 3), which may even have been an "r"
> originally; and at the top of the second "i" of an "okodaiin" (line 2,
> word 1).
>
> The reason why we don't see more of such evidence could be that there
> was no retracing... or that the original text has mostly faded to
> invisibility. Check for instance the plume on the first word
> ("tsheos"), which I would guess is "old", and the EVA "y" (your "9")
> on the next-to-last word of the first parag, "otchody", which I guess
> had its head (but not its tail) retraced with an almost-dry pen. Under
> the "retouching" hypothesis, those details were still above the
> visibility threshold at the time, so the "old" characters that were
> traced-over should be even fainter.
>
> I can't reply to all of your other points here, unfortunately. (This
> thread seems to be snowballing, each line of one posting calls for two
> paragraphs of reply...) I will try to expand my webpage with a more
> systematic and organized list of examples. For now I can only say
> that, while most instances of "retracing" could be explained by
> "natural" accidents with a sufficiently magic ink, there are far too
> many examples to explain them that way.
>
> On the whole, "retracing" seems to be a much simpler explanation for
> all that evidence. It does not require UFOs or bizarre sects or
> super-human cryptographers/forgers, nor unspecified ink chemistry --
> just an ordinary book owner doing a very simple and natural thing, for
> a very plausible reason...
>
> As for the colored paints, not only the visual evidence but simple
> common sense point to them being the work of a later owner.
> That would hardly be an unusual occurrence: see
>
>   http://special.lib.gla.ac.uk/exhibns/month/oct2002.html
>
> for an example of a *printed* book that was completely and carefully
> colorized by a later owner. (Scroll about 2/3 down the page for the
> story.) On
>
>   http://www.med.yale.edu/library/historical/fuchs/
>
> you will find another copy of this same book - Fuchs Herbal - where a
> few pages have been fully (but crudely) colorized, a few more had only
> the leaves painted green, and the rest was still unpainted.
>
> So I think that the burden of proof is on those who claim that the
> painting is original, not on those who believe it to be a later
> addition. (For instance, it would be a good start to find a single
> example of brown text or outline written on top of the paint, rather
> than under it.)
>
> All the best,
>
> --stolfi
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