In 2012, the National Gallery of Slovenia received a
donation of thirty-seven sculptures by Frančišek Smerdu. Plaster casts possess
a special kind of spontaneous charm. They are often made from cheap materials
that can be found lying around in a sculptor's studio. In Smerdu's case, his
casts were mostly used as models for stone carvings or bronze castings, or
functioned as maquettes, documenting the work's creative path from ideation to
final form. As such, plaster casts are precious documents offering an
unfiltered access to the artist's creative process.
The conservation of the Smerdu donation was a
challenge for the Gallery's restorers, which worked on this project for 8
years. Plaster itself is a fragile material and highly sensitive to water,
moisture and mechanical stress. Moreover, plaster casts are complex systems;
they often contain reinforcements made from various materials (wood, canvas,
metal etc.) which age differently and thus influence the condition of the
whole. The relief Motif from the National
Liberation Movement is a good example of this complexity.
The
conservation treatment
Upon arrival to the
restoration studio of the National Gallery of Slovenia, it was immediately
clear that the relief was in a bad state of conservation. The surface of the
work was covered in a dark layer of dust, and the relief itself had significant
cracks and was structurally unstable. The specific construction method used by
Smerdu also meant that we were severely limited in the range of available
treatment options for the object.
How
did the damage occur?
Smerdu cast the relief in two layers. To reinforce the
structure, he submerged a piece of canvas in the first pour of plaster, and
encased two wooden boards in the second pour, which are still visible from the
back of the relief. Fluctuations in humidity and temperature caused the wood to
contract, expand and warp, which consequently caused the plaster to crack and
break with it. The plaster fragments were kept together only by the canvas
reinforcement and the wooden planks.
Surface
cleaning
We began the conservation treatment by gently
vacuuming the front and the back of the relief. More dust was removed using
latex-free make-up sponges. Next, we used a water-based gel made with Agar, a
strong gellant extracted from a type of algae. Agar gels are able to retain a
considerable amount of water and thus allow the use of wet cleaning methods on
fragile and water-sensitive surfaces such as plaster. We poured slightly warm
Agar gel on the surface, let it cool, and harden for a few minutes. Then we
simply peeled it away with the remaining dirt, which bound itself to the gel.
Lastly, we removed the thicker patches of dirt mechanically, with a scalpel.
Stabilizing the structure
The canvas
reinforcement, which still linked the broken fragments, was a huge obstacle
when attempting to stabilize the structure of the relief. The canvas did not
allow us to apply the adhesive evenly inside the cracks. Instead of gluing, we
decided to inject a filler into the cracks and thus stabilize the structure by
filling the voids between the broken pieces. The filler material was applied by
brush or injection and the eventual overflow was cleaned with acetone.