Paper Conservation: Decisions & Compromises

The Migration of Hydroxy Propyl Cellulose During Consolidation of a
Painted Wallpaper: A Case Study Using a Fluorescent - Labelled Consolidant
Tilly Laaser | Karolina Soppa | Christoph Krekel
Staatliche Akademie der Bildenden Künste Stuttgart, Germany;
Hochschule der Künste Bern, Konservierung und Restaurierung, Bern, Switzerland
Introduction
This paper presents the evaluation of a consolidation
method planned for a painted wallpaper
in the Neues Museum Berlin in 2007. Five years
before, the painted surface had been secured
with facings applied with Klucel® (hydroxy propyl
cellulose) solved in ethanol. A method for
their removal and simultaneous consolidation of
the weakly bound and partly flaking paint layer
was proposed by the conservators in charge and
evaluated by researchers at the State Academy of
Art and Design Stuttgart with test objects. 1 The
penetration behaviour of hydroxy propyl cellulose
in the test wallpapers was visualised using
fluorescent labelling. 2
Fig. 1: Fluorochromization reaction between hydroxy propyl cellulose
and FITC ‘Isomer I’, forming a stable, fluorescing conjugate.
Original wallpaper and conservation
problem
In 2008, the Neues Museum Berlin was restored
and reopened for the public after it had been
severely damaged in World War II. The ceiling
wallpaper is part of the original interior fittings
from the 1850s. Originally, maculature and paper
supports had been attached to the ceilings
of the Mythologischer Saal and afterwards been
painted in situ with glue-bound distemper. 3
After having suffered different damages connected
to the partly destroyed museum building,
the 250 m 2 of wallpaper were treated by conservators
in 2002. The painted surface was secured
with facings applied with hydroxy propyl cellulose
dissolved in ethanol and the partly detached
wall paper removed from the ceilings and transferred
to a storage in anticipation of further conservation
treatment.
At the beginning of the wall paper’s conservation
in 2007 4 , it was not possible to remove these
facings from parts of the paint surface without
risking paint loss. Thus, a method comprising
their removal and consolidation of the weakly
bound and in parts flaking paint was proposed
by the conservators and investigated on test objects
specially designed for this study at the State
Academy of Art and Design Stuttgart.
Method and testing
The fluorescent labelling of hydroxy propyl cellulose
5 with Fluorescein-5-isothiocyanate (FITC
‘Isomer I’) was executed before its application,
thus guaranteeing a precise detection of the
latter. During the fluorochromization reaction,
FITC and hydroxy propyl cellulose formed a stable
bond (see Fig. 1). Any free fluorochrome was
removed in a subsequent dialysis.
The non-fluorescing test wallpaper was produced
by glueing together two layers of paper
with wheat starch paste which were then painted
with several layers of glue-bound ultramarine
(see Fig. 2). 6 The test wallpapers were treated with
a fluorescent-labelled hydroxy propyl cellulose
(corresponding to the first conservation treatment
in 2002): Facings consisting of Japanese
tissue 7 were attached to the paint layer of the
test objects with a ten per cent solution of the labelled
cellulose ether in ethanol. Having allowed
a sufficient period of drying, it was now tried to
remove the papers and at the same time use the
facings’ adhesive to consolidate the paint layer
(corresponding to the current conservation treatment).
The conservators in charge suggested that
the hydroxy propyl cellulose should be treated
ICOM-CC Graphic Documents Working Group Interim Meeting | Vienna 17 – 19 April 2013
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