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Subject: Flaking ink on manuscript

Flaking ink on manuscript

From: Jack C. Thompson <tcl>
Date: Saturday, July 11, 1998
Of the two conditions mentioned ("Either the binder in the inks has
failed, or is not adhering to the surface of the vellum.") it is
most likely that the ink was produced without sufficient binder.

If the pigments were also flaking I would suspect that the skin was
sheep and that some fats/oils remained in the skin, more or less
repelling water-based inks/paints.

However, there is another possibility.  If the area where the ink
was put down shows where the ink had been (i.e., if the surface was
destroyed there by the ink before it flaked away) it is likely that
too much ferrous sulfate (copperas) was used in compounding the ink.
This can easily happen if the person making the ink used dehydrated
ferrous sulfate in a recipe which assumed that crystalline ferrous
sulfate would be used.  The resultant ink would contain
approximately 35% more sulfuric acid than if the crystalline form
had been used.

I have not seen very many exemplars which exhibit this problem, and
have not seen this one so I hesitate to go much further.

If there are a few flakes laying around in the gutters of the book,
it would be useful to have them analysed for the presence of
glycerine (suggesting the use of wine, vinegar, ale, etc. to extract
tannic acid from galls or bark) and/or gums (gum arabic, cherry or
plum gum, etc.).  It is also possible that no binder was used.

Solutions to the problem depend, in part, on the answers to these
questions.

Jack C. Thompson
Thompson Conservation Lab.
Portland, OR  97217
503-735-3942  (voice/fax)

                                  ***
                  Conservation DistList Instance 12:10
                  Distributed: Tuesday, July 14, 1998
                       Message Id: cdl-12-10-001
                                  ***
Received on Saturday, 11 July, 1998

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