Paper Conservation: Decisions & Compromises

Fiber Optic Reflectance Spectroscopy (FORS):
A Useful Technique for the Analysis of an Early 20th Century Livre d’Artiste
ana margarida silva | márcia vilarigues | maria joão melo | vicarte | marcello picollo
Department of Conservation and Restoration, Faculty of Sciences and Technology,
New University of Lisbon, Portugal
Institute of Applied Physics ‘Nello Carrara’, Florence, Italy
In paper conservation the analysis of materials is
often quite difficult due to the fact that in delicate
art work paint layers are usually very thin
and small in size. The use of in situ non-invasive
techniques is recommended as the most appropriate
analytical tool.
The analysis provided by Fiber Optic Reflectance
Spectroscopy (FORS) is useful in these
cases. The proposed in situ non-invasive technique
operates in the ultraviolet (UV), visible (Vis)
and near-infrared (NIR) regions (350–2200 nm).
It allows scientists and conservators to identify
different compounds, especially pigments and
dyes, to evaluate colour and colour changes and
to detect alteration products. Proper instrument
configuration may promote the achievement
of these goals with just a single measurement.
This methodology is based on the measurement
of the diffuse radiation from the surface when
compared with a standard of calibration, such as
Spectralon® or barium sulphate plates.
This case study presents a livre d’Artiste by
Amadeo de Souza-Cardoso (1887-1918), the most
important Portuguese artist of the Avant Guard
movements from the beginning of the twentieth
century in Western Europe. The book entitled
La Légende de Saint Julien L’Hospitalier (1912)
was copied and illustrated by the artist from the
tale of Gustave Flaubert, resulting in a piece of
artwork. The decorative elements, illustrations,
and text link each other gracefully, the result of
which is a modern reinterpretation of a medieval
codex. This beautiful and unique piece is now
at Centro de Arte Moderna – Fundação Calouste
Gulbenkian’s collection in Lisbon (Portugal).
The poster illustrates the effective use of FORS
in the analysis of this book. On analysis of the
book’s production, FORS technique confirmed
the use of parchment in the bookbinding. FORS
also offered interesting information about the
watercolour’s molecular palette, rich in coloured
and stable pigments, which corroborates previous
studies, with the exception of the blue colours.
Gold and silver were also identified as well
as alterations in silver. However, not all pigments
can be identified in the 350–2200 nm range by
FORS, because some materials have similar reflectance
spectra: for instance, cadmium red and
vermilion. The black pigments were not easily
identified because they show a strong absorption
that masks almost all of their spectral features.
When necessary, analyses were complemented
with micro-X-ray fluorescence spectroscopy and
micro-Raman spectroscopy.
The application of FORS proved to be useful
to paper conservation, providing in situ non-invasive
analysis. The advantages of FORS include
among others, the portability of the instrument
(which allows analysis on site) and the ability to
analyse the acquired spectra in real time.
Authors
amcd.silva@campus.fct.unl.pt
mgv@fct.unl.pt
mjm@dq.fct.unl.pt
m.picollo@ifac.cnr.it
ICOM-CC Graphic Documents Working Group Interim Meeting | Vienna 17 – 19 April 2013
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