Paper Conservation: Decisions & Compromises

edges. To imitate the colour of the original paper,
the irregular colour patterns of the adjoining
original paper parts were used as an orientation
and brought together in the middle of the
insert. The inserts were trimmed and chamfered
to the exact shape of the loss and received a final
toning with watercolours along their edges. During
the dyeing processes the colour was observed
several times under different light sources to test
for metamerism 3 .
3. Stabilizing the toned insert by lining and
coating
To stabilize the larger insert and to protect it
from possible later distortion, in the case of
climate changes in the future, the larger insert
paper was lined verso with a thin Japanese kozo
paper. The Japanese paper had been prepared
by coating it with Lascaux® 498HV adhesive,
and was applied to the verso of the insert by
reactivating the adhesive with heat. The lining
enhances the dimensional stability of the insert
paper and protects it against distortions. The adhesive
and the application method were chosen
on the basis of tests conducted with insert papers
lined with either starch paste, methylcellulose or
Lascaux® 498HV that had been exposed to cycles
of fluctuating humidity (50-95% RH). The samples
were measured before, during and after the
humidification to check the degree of extension.
The test showed that only the samples prepared
with Lascaux® 498 HV were dimensionally stable
when exposed to high relative humidity. Furthermore,
to smoothen the surface of the retouching
paper after the extensive colouring processes,
diluted methyl cellulose (Methocel® A4C) was applied
with a spray gun and the surface was then
dried in contact with a piece of polyester fabric
(Bondina®).
Fig. 2: Robert Delaunay, “The three Graces, study for ‘The
City of Paris’”, normal light, after treatment (08.08.2012).
4. Shaping and attaching the inserts
To create a smooth transition from the insert
paper to the original, the edges of the insert
were chamfered from the back at a width of
5 to 10 mm. Finally, the insert was adhered to the
edges with starch paste, minimizing the area of
adhesion, at some areas minimally overlapping
onto the original by about one millimetre to
cover dark stained edges, revealed after removing
the former overlapping paper fills. The new
inserts remain removable, leaving the historic
treatment of the artwork accessible. With the
old fills covered, their prominent visual distraction
is eliminated, allowing a more focused perception
of the painting (Fig. 2). Both retouched
inserts achieve a good colour match with the
whole picture. They are in-plane with the original
also along their adjoining edges where there
is no noticeable step in part due to the conformable
nature of the insert paper. The retouched
insert surface is very similar to the surface of
the original. No metamerism effect was noticed
when viewing the insert and the original under
different light sources.
Outcome and outlook
Where the old insert overlapping edges were
removed from the original, newly revealed original
paper areas and small parts of the picture
indicate design details critical to the understanding
of the painting. The project required many
micro-steps of technical and aesthetic decisionmaking.
Key to its success was the continual,
interdisciplinary consensus building in which
preservation and aesthetic concerns were communicated
in a differentiated way. At this point,
the oil sketch will be examined together with
ICOM-CC Graphic Documents Working Group Interim Meeting | Vienna 17 – 19 April 2013
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