Iron gall ink and discoloration

Barry Knight <barry.knight<-a t->bl< . >uk> writes

>Florane Gindroz <florane.gindroz<-a t->bluewin< . >ch> writes
>
>>At the Bibliotheque de Geneve we've got a manuscript on vellum on
>>which someone used a solution applied with a brush probably in order
>>to improve the contrast of the iron gall ink (or to copy the
>>manuscript?).  Now the surface is light blue and the ink dark blue.
>>However, in some parts it became hardly readable (conglomerate).
>>
>>Does anyone know about this phenomenon and know how it could be
>>reduced?
>
>At some time in the past, your manuscript has been treated with a
>solution of potassium hexacyanoferrate (III), (potassium
>ferricyanide) in order to restore the colour of faded ink. ...

Thanks a lot for this helpful information.  Another colleague
explained me that this treatment had to be applied on wet vellum and
it was left in this state overnight.  That's why our manuscript is
also very stiff and slightly translucent.  As you recommend, we will
try to reinforce the contrast through imaging.  Before doing so, we
could reduce the calcium carbonate crystallization anyway.

Florane Gindroz Iseli
Head of conservation lab
Bibliotheque de Geneve
Geneva


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                  Conservation DistList Instance 27:43
                    Distributed: Sunday, May 4, 2014
                       Message Id: cdl-27-43-001
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