Page 101 - TINA Dergi Sayi 08

TINA

Maritime Archaeology Periodical

The encrustation examined under X-ray is di-
Fig. 20
vided into two parts, and iron oxide powder is
completely cleaned. Then, the gap defining the
form of the artifact is filled with a two-compo-
nent high-viscosity epoxy resin. The two parts
separated from the beginning of the installati-
on are joined together in the same way, and the
joint is covered with plasticine to prevent the
epoxy from pouring out from its edges. After
the epoxy filling is completely dry, a copy of the
epoxy casted artifact is obtained by thoroughly
cleaning the encrustation with a vibrating equ-
ipment, which is driven by a compressor and air
blast (Fig. 17-19).
The more important is the cargo carried by the
ship, the more important is the recovery of the
remains of the ship’s hull. It allows us to un-
derstand evolution of shipbuilding techniques
and have information about the economic con-
dition of the society at that time in the histori-
cal development. However, wood is one of the
most deteriorated materials in marine environ-
ment. There are different causes and grades of
biological, chemical and physical deterioration
of the wood, depending on the environment (ae-
robic, anaerobic environments and temperature,
humidity, pH, redox potentials) and the period
of stay in this environment. These finds, which
Fig. 21
have been under water for a long time, are deg-
raded by other biological factors such as bacte-
ria, sea life, as well as deterioration caused by
humidity increase of cell wall components. The
most common method for water-saturated wood
preservation is polyethylene glycol (pEG). INA-
The Institute of Nautical Archeology applies
pEG impregnation method for conservation of
wooden parts of a ship in its laboratory for wood
(Fig. 20-22). The basic principle of pEG app-
1
lication is to discharge the water from the cells
filled with water, and replace it with pEG of dif-
Fig. 22 ferent molecular weights, which is a water-so-
luble synthetic polymer instead.

5 pEG is a corrosive substance. Since the pH value of the pEG solution is between 4.5 and 7, it can react with all metals, especially
iron, and cause corrosion. For this reason, wood must first be cleaned of metal residues on its surface before the application of pEG
in water saturated wooden artifacts. Desalination should be carried out in all underwater artifacts as well as in wooden artifacts
before pEG application and the purification process should be continued until the conductivity reaches 50-100µS / cm.
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