Paper Conservation: Decisions & Compromises

sharp view of the cross sections and a clear detection
of the fluorescing consolidant within the
sample while weak auto fluorescences of the materials
were eliminated.
Fig. 2: Photos in visible light of thin sections (8 µm) of the original
wallpaper (left) and the test wallpaper (right). Layers: 1 Paper support,
lower layer; 2 wheat starch layer; 3 Paper support, upper layer;
4 paint layer.
with ethanol and the dissolved consolidant be
transported into the paint layer and between
paint layer and paper support by means of low
pressure, avoiding however the impregnation of
the paper support. Application method and residence
time of the solvent, as well as exposure to
low pressure were varied (an overview of the conservation
treatments can be seen in Table 1).
After the consolidation method had been tested,
samples were cut out, embedded in Technovit
2000 LC and cut with a microtome into 8 µm
thick layers. The thin sections were examined
with fluorescence microscopy using a filter set
specially designed for FITC. The non-fluorescing
test wallpaper appeared black while the labelled
hydroxy propyl cellulose exhibited a bright green
fluorescence. The thin sections allowed for a
Results
It was shown that different migration depths
could be achieved by varying the application
method of ethanol and by the time the test objects
remained on the suction table (see Fig. 3).
Best results were achieved when only applying
the ethanol from the front and removing the test
objects from low pressure as soon as the facing
had been removed (treatments A and C). The consolidant
accumulated between support and paint
layer as well as within the weakly bound paint
(visible in higher magnification). Exposing the
sample to low pressure before the facing’s removal
(2 min. in treatment C) had only little impact
on the migration depth. Applying the ethanol
also from the back (treatment B) resulted in the
undesired effect of a slightly deeper penetration
of the consolidant; however, the consolidant
migrated mostly between paint layer and support
as well as into the paint layer. Leaving the
test object on the suction table after the removal
of the facing (treatment D) lead to the complete
penetration of the consolidant into the paper
support while it was not any longer visible on or
within the paint layer. This treatment was thus
eliminated as an option.
Based on these findings, it was possible to
choose the appropriate parameters for the hydroxy
propyl cellulose to migrate into the weakly
bound paint and accumulate between paint layer
and support without risking impregnation of the
paper support.
The application of fluorescent-labelled consolidant
on test objects designed for the conserva-
Test painting Ethanol application Removal of facing on suction table Left to dry on suction table
A from the front (5 min swelling) immediately no
B
from the front and from the back
(5 min swelling)
immediately
no
C from the front (5 min swelling) after 2 min no
D from the front (5 min swelling) after 2 min yes
Table 1
Conservation Methods tested
ICOM-CC Graphic Documents Working Group Interim Meeting | Vienna 17 – 19 April 2013
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