Study of stability of brown-gray inks on paper support

Abstract

Research into paper artworks and the identification of drawing techniques dating from the 15th to the 19th century from the collection of Slovak National Gallery revealed that the most frequently used means of writing was a set of brown-gray inks. This set includes bistre, sepia, and iron-gall inks (IGI). The light fastness of these organic compounds is not considered very high. Moreover, iron gall inks attack paper support by the processes commonly known as iron gall ink corrosion. In the experimental part of the research, the stability of three different brown-gray inks was studied. Model inks, i.e. bistre, sepia and IGI with two molar ratios Fe : gallic acid were prepared according to historical recipes. Whatman paper was used as a support material. Samples were submitted to accelerated aging in closed vessels at 100°C with and without the presence of NO 2 in concentration of 100 ppm as well as to the light aging in a light chamber. Changes of mechanical, optical and chemical properties of the samples as well as spectra in the IR region were studied. The observed changes allowed an evaluation of the effect of particular inks on paper support and effect of various external factors of aging (temperature, light, pollutants) on the model systems. Simultaneous thermal analysis (DTA/TG) was carried out in order to study the thermo-oxidative stability of the materials. Sepia and bistre inks have been assessed as generally more stable than iron-gall inks.

A study of the deterioration of aged parchment marked with laboratory iron gall inks using FTIR-ATR spectroscopy and micro hot table

“…As a result, in hydrolysable tannins, iron (III)-gallate coordination complex is responsible for the typical blue-black colour, while the analogous ellagate complex is similarly coloured. On the other hand, complexes of iron with oxidation products of the initial favan-3-ol (or catechin), which are components of non-hydrolysable tannins are brown-green or brown-grey [30,31]. Moreover, ternary complexes of iron (III) with gallate having various colours have been investigated, also involving amino acids such as glycine.…”

Application of Raman Spectroscopy to Ancient Materials: Models and Results from Archaeometric Analyses

“…The breakage of important bonds in the parchment structure, as a function of the time, would be easily detected by Raman spectroscopy [37,42,43]. Another example can be found in the progressive acidification and degradation of medieval black inks (principally iron gall), which causes important problems in manuscript corrosion [44,45]. Moreover, in this case, the progressive acidification of the ink can be monitored by means of Raman spectroscopy and a kinetic model can be proposed to study the conservation state.…”

Vibrational Study (Raman, SERS, and IR) of Plant Gallnut Polyphenols Related to the Fabrication of Iron Gall Inks

“…IGIs were historically the most important and common writing and drawing material until the beginning of the 20th Century [ 15 , 16 , 17 ]. The reasons for that are their simple preparation, the good quality of the written records, their indelibility, as well as not clogging writing pens and brushes [ 18 ].…”