Paper Conservation: Decisions & Compromises

Fig. 2: Filmoplast® tape attached on the ink layer on the verso
of one of the prints
Fig. 3: Sampling under microscope of the tape carrier
were taken under microscope, as was a sample
of the clear plastic support, shaved from the very
edge of the object. A sample of each type of tape
was also taken at the lifting edges (Fig. 3).
FTIR, Raman, GC-MS and LDI-MS (Laser Desorption
Ionization-Mass Spectrometry) were used in
order to determine the composition of the plastic
support, pigments (red and blue) and tapes
(carrier and adhesive).
Results
After GC-MS, the results show that the clear
support is not made of acetate as stipulated in
all the descriptions, catalogues or even on the
invoices the printing company sent to the Wadsworth
Athenaeum, but it is polystyrene. It is interesting
to note that today it appears that PVC,
polyethylene, mylar, and acetate have mostly
replaced polystyrene as clear and thin plastic
printing surface. Polystyrene is now mostly sold
as extruded white foam. LDI suggests that the
blue pigment used is PB15 (phthalocyanine blue)
which was a pigment commonly used for printing
ink. The red ink sample contains chrome red,
PR63, and barium sulfate. The binder of the inks,
both red and blue, is made of polystyrenes; it is
a plastic ink which is specifically for printing on
plastic. GC-MS identified the carrier and adhesive
components of the Filmoplast-like tape as a cellulosic
material as assumed it was; and the office
tape as PVA.
These results were interesting as they led us
to develop a conservation procedure. Because
the support and the ink binders were both polystyrene
and thus probably well bonded, we felt
more confident that the bond was strong enough
to support gentle mechanical removal of the
tape.
Conservation project
After various tests, the best option was to mechanically
remove the tape and tape adhesive.
Attempts were carried out using tweezers peeling
at an acute angle to remove the tape and
various white vinyl eraser pencils of different
hardness and shape were used to reduce the adhesive
residues. Every step was carried out under
microscopic observation to prevent any scratches
or physical damage on the surface of the prints.
On one copy, it was possible to remove the
Filmoplast-like tape carrier first by applying
warm water with a very small brush; this softened
the tape carrier, making it removable
without affecting the ink. The tape carrier was
then removed with tweezers. Then, some cellulose
powder 1 was scattered on top of the sticky
residual adhesive and the adhesive plus cellulose
powder was pushed away with a color shaper
tool 2 without scratching the surface or removing
ink. It appeared that in this case, instead of using
an eraser pencil, a color shaper tool was more
successful in reducing the adhesive residues. The
results were very satisfying (Fig. 4).
For the acrylic-based office tape on the other
ICOM-CC Graphic Documents Working Group Interim Meeting | Vienna 17 – 19 April 2013
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