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Introduction
Iron gall ink was the ink of choice for centuries in
western history. Its chemical instability has caused
a major threat to paper-based heritage. From the
perspective of long-term storage of archival
collections, this research focuses on the following
research question:
Can the synergistic effects of deteriorating agents
for paper containing iron gall inks that have been
identified in literature [1, 2], i.e. temperature,
relative humidity, iron(II) content, pH of ink lines,
paper grammage, and intensity of application be
quantitatively determined through theoretical,
experimental and statistical analysis?
Damage Function for Paper Containing Iron Gall Inks
Yun LiuUCL Institute for Sustainable Heritage, University College London, London, UK
Fig. 1 A manuscript damaged by iron gall ink corrosion (Credit: The National Archives, Kew, UK).
Methodology
Damage Functions in heritage science are
functions describing detectable physical or
chemical change in the context of value [3].
fDamage = fValue (fChange (x))
Where fChange =Δ𝐶ℎ𝑎𝑛𝑔𝑒
Δ𝑡
= f (environmental factor, material property)
References[1] Kolar, J., Stolfa, A., Strlič, M., Pompe, M., Pihlar, B., Budnar, M., Simcic, J., Reissland, B., 2006. Historical iron gall ink containing
documents — Properties affecting their condition. Analytica Chimica Acta 555, 167–174.
[2] Neevel, J.G., 1995. Phytate: A Potential Conservation Agent for the Treatment of Ink Corrosion caused by Iron Gall Inks.
Restaurator 16, 143–160.
[3] Strlič, M., Thickett, D., Taylor, J., Cassar, M., 2013. Damage Functions in Heritage Science. Studies in Conservation 58, 80–87.
AcknowledgementsThis project is supported by the EPSRC Centre for Doctoral
Training in Science and Engineering in Arts, Heritage and
Archaeology at University College London, in collaboration
with the Smithsonian’s Museum Conservation Institute, the
National Archives and the company Lichtblau e.K.
Expected Outcomes
The damage function to be developed for paper containing iron gall inks will be used to predict the fitness for use of iron gall ink collections based on
their current material state, in order to prioritize controllable environmental parameters. This will be a major contribution to the development of the online
collections modelling tool that will facilitate collection management via visualised data interpretation and collection management scenario exploration.
Fig. 4 Viscometric method
for DP determination.
Fig. 3 Cold extraction
method for pH
determination.
Fig. 2
Bathophenanthroline
test for Fe2+ identification.
Historical Iron Gall Inks typically contain tannic acid and iron(II) sulfate as
colour-forming components, as well as Arabic gum as the binder. Degradation
of inks results in a colour change of inks from blueish-black to brown as well as
loss of mechanical properties of paper support along ink lines in extreme cases.
Tannic acid extracted from gall nuts Gallic acid
+ H2O + Fe2SO4·7H2O
Insoluble
Fe(III)
gallate
complex
+
Arabic gum Ink
solution
Environmental Parameters
Material Properties
Paper Properties
Ink Properties
Dose-response Function
Damage Function for Paper Containing
Iron Gall Inks
Threshold Based on Value
Temperature
Relative Humidity
Grammage
pH of Ink Lines
Application Intensity
Iron ContentRate of Degradation
Degree of Polymerization (DP)
Physicochemical Approach
Epidemiological Approach
Non-destructive Collection Survey
Damage Function for Other Materials
User Control
Defined Input and Output
Online Collections Modelling Tool
Doctoral ResearchMRes Research
Psychophysical Approach
Model Validation
Experimental Approach
Theoretical Approach Theoretical FunctionArrhenius Equation
Ekenstam Equation
Testing Techniques Fig. 6 Data for modelling
were obtained from historic
samples using NIR
spectrometer in
collaboration with the
National Archives (UK).
Fig. 5 Thickness
measurement. 2 3 4 5 6
Milestones Experimental Parameters