Home Conservation projects The Conservation And Restoration Of A Wooden Monoxylon From The Depot Of The Karlovac City Museum

The Conservation And Restoration Of A Wooden Monoxylon From The Depot Of The Karlovac City Museum

Conservation and restoration work on a wooden monoxylon from the depot of the Karlovac City Museum were conducted from July of 2013 to July of 2015 at the conservation and restoration department of the International Centre for Underwater Archaeology in Zadar. The monoxylon had been stored in the museum's depot since 1966. Uncontrolled drying had weakened the fragile wooden structure of the boat leading to the appearance of numerous fissures and the crumbling of the walls of the boat. The boat is constructed from a single piece of wood, has an oval shape with a maximum length of 310 and a maximum width of 63 centimetres.

Conservation and restoration work on the monoxylon was initiated immediately upon its receipt. The objective of the conservation and restoration procedures is to retard the process of the artefact's deterioration, to conserve the condition as found, restore its former visual identity and provide for its long-term preservation. Samples from the surface layer were submitted to the Poznań Radiocarbon Laboratory in Poland, a specialised laboratory, in order to determine the age of the wooden material. The age of the wooden structure was determined using the 14C radioactive isotope of carbon method. The results of the radiocarbon method place the age of the wood between the years 1479 and 1640. The precision of the result is 95.4%.

The monoxylon was first subjected to cleaning, which involved the removal of dirt, including layers of dust, small-grained pebbles, sand, cobwebs and bits of plaster and wall paint.

The cleaning of the monoxylon was challenging because the layers of dirt were the only bond between the cracked surface and the wooden core. The removal of impurities was done mechanically and exercising great care, using soft scrubbing brushes and paintbrushes, surgical scalpels of various profiles and small hand tools. A vacuum cleaner was used in the cleaning process set to its lowest operating power. Textile netting was applied over the nozzle of the vacuum cleaner in order to prevent the vacuuming up of the unstable surface layer.



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Removing impurities

Cleaning was followed by the stabilisation of the unstable surface layer. The drying out of the wooden structure resulted in the cracking and separation of the surface layer of the monoxylon on all sides to a thickness of about one centimetre, creating fissures and micro-fissures on the surface that have given the surface layer a mosaic appearance. The surface layer on the inside of the monoxylon is partially missing, while on the outside surface it is missing along the entire length of one side and partially missing on the other side. The surface layer wiggles and falls off to the touch, i.e. it separates from the body. Stabilisation was achieved by the application of a liquid two-component epoxy impregnation for wood. The impregnation substance was applied by injection into the fissures and micro-fissures. Parallel to the application of the impregnation, the separated parts of the surface layer were repaired by gluing. The excess impregnation was removed from the surface using cotton pads impregnated with acetone. Stabilisation and repair of the entire surface layer was followed by the consolidation of the artefact.

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Injecting the impregnation substance

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Applying the consolidant

A 5% solution of thermoplastic Paraloid B-72 resin in acetone was used as the consolidant. The consolidant was applied with soft paintbrushes, patting on the consolidant in order to avoid damaging the artefact. The consolidant was applied in several layers. Integration was done at a gap in the prow of the monoxylon. The gap was integrated using Araldit epoxy resin for wood, reducing the possibility of the further widening of the gap and achieving greater structural stability. No signs of further deterioration were observed on the monoxylon following the conservation-restoration work – to ensure this stays that way the artefact must be stored in suitable conditions (relative humidity of from 45 to 60%, a temperature of 18°C and lighting of a brightness of under 200 lux). The use of cloth gloves is recommended when handling the artefact to best protect it from chemical and microbiological impacts.

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The monoxylon post treatment

 Marina Šimičić