Page 200 - Manual for Activities directed at the Underwater Cultural Heritage

© Swedish Maritime Museum. Conser vation of the Vasa, Sweden. The Vasa’s conservation began
as a huge experiment but the pioneering research by the conservators of the shipwreck
has paved the way for numerous other shipwreck projects around the world.
After examining a number
of possible methods and materials, the synthetic polymer polyethylene glycol (PEG) was chosen to treat the Vasa’s wood from drying out.
PEG spraying began in April 1962. The PEG concentration was gradually increased from a low concentration of 5 % and ending with a 40 % solution. Boron
salts were added to prevent microorganism growth and neutralize acids.
Various types of PEG were tested on the wreck over the years, and PEG 4000, 1500 and 600 have
all been used.The PEG ran over the hull’s surface, was collected
in tanks and re-used.The spray treatment lasted for 17 years, from April 1962 to January 1979, followed by another 9 years
slow air-drying.To strengthen the surface of the wood a final surface layer of PEG 4000 was applied.
 © U. Guérin / UNESCO. Long bows preserved in the Mary Rose storage room.
The bows have been stored on
a dr y and smooth surface and are kept in a drawer, which is well identified and safe from unauthorized outside access.
 © T. Maarleveld. Storage area of the Zuid-Holland repository, Netherlands.
Repositories for long-term storage of archaeological finds can become quite extensive.They need to be organized in the form of true archive or library with
a systematic catalogue referring to each object in the collection and its location on the shelves. Standard boxes of appropriate material are used for storage of most objects in the Zuid-Holland repository.
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Conservation and site management