Paint restoration
During the reconstruction of Knossos by Arthur Evans, the frescoes were replaced by copies, while the originals are now on display in the Heraklion Archaeological Museum. The copies are now an integral part of the site with historical value.
It is evident from macroscopic observation that the replicas have been applied to some kind of chipboard or wood. Their suspension method is not obvious. In some places, special support points or wooden laths appear to have been placed, combined with mortar. Over this substrate is a layer of cement. Lastly, paint has been applied, forming a sort of film on the final surface of the substrate.
During the conservation work on the copies of the frescoes in the context of the 3rd CSF, a conservation study was drawn up and implemented.
First the surfaces were cleaned. Where there was good attachment to the substrate, the results were satisfactory. Where there was flaking, however, cleaning was difficult due to the lack of cohesion, so the surface was first consolidated.
As part of the restoration of the copies, some repairs were made to those areas where the loss of the painting surface was so extensive that it resulted in serious aesthetic discontinuity, strikingly visible to the viewer. The repair mainly helped increase the cohesion and retention of the layers of the copy.
The materials used for the repair were gypsum, a material related to the construction technology of the fresco substrate, and acrylic filler, suitable for filling cracks due to its elasticity. Finally, where the painting surface was lost, powder pigments were used with acrylic mortar, in the same colour as the existing paint.
The work also involved the restoration of the imitation wooden structures of Evans’s reconstruction, by the use of abstract art imitating wood rather than a faithful copy. It was also considered essential that the colour should match that of the masonry, producing a visual result that does not stand out but is incorporated into the overall picture of the monument.
During Evans’s restoration work, large areas such as the “South Propylaeum”, the “Royal Apartments” and the “Piano Nobile” were roofed with reinforced concrete. The same material was used for architectural members such as columns, pillars and door jambs. On the contrary, wood, the original Minoan material of which they were made, was not preserved anywhere.
With regard to the columns, their stone bases have been preserved in most parts of the Palace. In the first reconstruction attempts, in the “Throne Room” and the “Grand Staircase”, the material chosen for their reconstruction was stone. First the shape of the column was carved out of stone, then the surface was plastered and finally the layer of paint was applied. Later, for example in the “South Propylaeum”, reinforced concrete was used. The columns were cast in moulds and then painted. The shape, with the characteristic tapering from base to capital, and the colours of the columns were drawn from the Minoan frescoes.
Various types of damage were observed to the columns, such as loss of paint, dust, presence of salts, loss of cohesion of the paint layer and cracks in the concrete.
The conservation work on the columns of Evans’s reconstruction carried out in the context of the 3rd CSF project were mainly cleaning of the surface of pollutants, oily stains, earlier interventions, guano and bird nests. Since most the columns are in outdoor areas and are made of concrete, German KEIM mineral paints were chosen for their aesthetic reconstruction, with very satisfactory results, mainly due to their durability in the open air under variable climate conditions. These paints are based on sodium silicate, which enters the pores of the concrete creating a very strong bond.