In 2015, during the preparations for the “Piranesi. Before and after, Italy and Russia in XVIII-XXI” exhibition, about 50 etchings of the renown Italian engraver Giovanni Battista Piranesi were sent to the Department of Conservation. The etching technique is a type of engraving on metal made with acids that leave traces on the surface of a metal sheet.

The collection curator, Y.Merenkova, told the conservators how the etchings found their way to the museum. The etchings from the series Roman Antiquities, On Greatness and Architecture of the Romans, Campus Martius, A trophy or a magnificent twisted marble column were submitted to The Pushkin State Museum of Fine Arts in 1930 from the Central conservation workshops. They were printed in Paris by the sons of the artist, who moved to France from Rome. Evidently, the etchings were made in the first third of the 19th century. The prints from the series Imaginary Dungeons, and Antique vases, candelabra... originate from the collection of the Polish noble family Kossezki and came to The Pushkin State Museum in 1924 from the Rumyantsev Museum. A proprietary stamp on the flyers of two volumes with a series of etchings Antique vases, candelabra..., helped to shed light on their origin: a coat of arms under a helmet crowned with a noble crown.  Under the coat of arms there is a ribbon with an inscription: "ZbibliotekiKossezkich".  This proprietary stamp belonged to Ksawery Kossezki (?–1857), a Polish army general, state councilor, publisher, translator and numismatist, and his son Stanislav. The Kossezkis' library in Warsaw contained two thousand tomes. It is known, that after its owners' death, the library was sold through the Warsaw antiquary of Abraham Rosenwen. In 1910s the folios from the Kossezkis' collection ended up in Moscow with a bookseller Harry Martinson, which is evident from the paper labels inside the front covers of the tomes: "HarryMartinsonLibraire. Moscou". Martinson's book shop was found in 1910 and specialized in buying and selling rare books on architecture and art. Some etchings with the views of Paestum came from the State Museum Fund, presumably in the late 1920s. Unfortunately, it was not possible to establish their previous owner.

Piranesi's etchings were sent to the workshop due to the visible damages: mechanical (breakage, rupture, jamming, losses of the base), oxidation of the paper (so-called "brown spots"); biological damage (mold fungi in particular), as well as various types of surface contaminations. Some of the prints reach more than two meters in size, which was difficult for the conservation; storing such large works without subsequent mechanical damage and external influences on paper was also an issue. It is the improper storage conditions that can cause damages to prints. The temperature and humidity conditions, the effects of the UV rays, as well as the place and method of storage are very important.

The preparations for the treatments included photographing the pieces in direct and side lighting, documenting their state of preservation. The base and the paint layer of the prints were tested for water and chemical resistance. As a result, chemicals were selected for each type of damages.

The program of treatments was developed for each piece individually. The first stage was mechanical cleaning. It was done with erasers made of different types of resin, which had different abrasion qualities, as well as scalpels used for tougher stains, and brushes for dust and other particles removal. This stage is usually very important, because on later stages, when the prints are immersed in water, if the dirt is not sufficiently removed, it penetrates the paper deeply, which sometimes makes its removal impossible.

Some of the larger prints made on several sheets of paper were glued into albums. Before the mechanical and water treatments, the prints were unmounted from the albums by dissolving the adhesive with damp poultices. This was done with a special spatula and absorbent fabric, which prevented possible staining. Damp poultices cause the glue to swell, which allows to carefully remove the sheets from the album with no damages.

The water treatments in the crates of warm water helped to remove some stains and yellowing of the paper. What was important is to not damage the sheets during the washing, as damping the paper weakens its fibres. The etchings printed on a non-woven polyester substrate were immersed in cuvettes with warm water, the water was changed several times as needed. Some large multicomponent sheets were taken apart for this stage: just like with dismounting, the glue would swell in the water, which made it possible to separate the sheets without damaging the etching.

The next step was to remove the brown spots and mould stains, which was done under a fume hood. The chemical reagents selected during the research stage were applied to the damaged areas, while the images were covered with conservation paper, so as not to damage the paint layer. The intensity and changing of reagents depended on how much lighter the stains would get. Between the changes of the reagents, it was necessary to wash the sheets in distilled water in order to prevent the chemicals to react with each other. When the stains were weakened, the engravings were washed thoroughly till complete decomposition of the reagents and dried on the table under a non-woven polyester cloth.

Then the etchings while still damp were mended with starch glue, the tears and creases were consolidated with Japanese paper. The areas of loss were filled with paper pulp, which was made from paper identical to the one of that time. To create the pulp, the paper was boiled, to boil out all the unnecessary ingredients, in this case an adhesive used as a binder. In some areas, the paper was tinted with special pigments to make it look natural and resemble the original paper. After the boiling, the conservators added a specially prepared binding adhesive to the pulp. Thus, the old glue was boiled out of the paper, and new, high-quality glue was added to it, which guaranteed a better binding of the fillings with the original paper.

As for the large scale multi-components pieces, it was decided not to attach the sheets to each other, like it had been done before, but rather to put them together in a passe-partout, to recreate their original look.

One of the last stages of the conservation treatments was pressing the pieces between felt sheets in a printing presses for two weeks until the glue was completely stabilized, changing the old sheets for dry ones from time to time. This allowed to straighten the etchings. Later, after being placed in passe-partouts made of acid-free cardboard, the etchings would not be subjected to excessive deformation and would retain their look for many decades. Art conservators retouched the etchings in places of fillings. The objective was not to complete the work, but only to tint the areas slightly.

In the end, photographs were taken and the whole process of conservation documented. Art conservators have been keeping handwritten journals since the day the workshops were first opened in the museum. There they document the stages of conservation treatments, together with dates and other details. There they also keep the descriptions of the state of preservation of the pieces.

Conservators who worked on this project: Marina Frolova, the head of the Graphic Art Conservation workshop, Natalia Seregina, Maria Sapronova and Maria Shakhalova.

After the work was finished, the Piranesi etchings were returned to the depositary to be exhibited later.