solution. Finally, water storage of archaeological wood should not exceed a
period of 3–5 years.
3.6 The Storage of the Mary RoseHull
With large structures such as the Mary Rosehull, where dismantling is
impractical, tank storage methods can be difficult to achieve due to the size of
the tank needed and the inaccessibility of the wooden structure once in stor-
age. In such instances, direct spraying of the wooden surface is employed. The
spraying of ships and other large structures with freshwater has an added advan-
tage in that the sediments and salt deposits are washed out. However, a major
problem with the passive storage of a large structure such as the Mary Rosehull
is one of size. Conservators have developed storage methods for small finds
and most are not capable of expansion to a larger scale. Thus, the only suitable
method to passively store the hull was spraying. A research programme was set
up to compare a warm (20°C) and a cold (5°C) spraying regime using original
ships’ timbers. The data obtained were predictable, showing significant differ-
ences in bacterial activity between the higher and lower temperatures. Main-
taining a water spray temperature of between 2 and 5°C substantially reduced
the degree of microbial activity within hull timbers. Based upon these find-
ings, a low-temperature spraying regime was adopted by the Mary Rose
Trust. The reasons were as follows: (i) water saturation of the hull timbers
would be maintained by the constant flow of water; (ii) temperature of the
spray water would be maintained between 2 and 5°C (at these temperatures,
microbial activity is well below the optimum growth temperature of marine
and terrestrial fungi and wood-degrading bacteria); (iii) the method is safe;
and non-toxic and (iv) this method is compatible with future conservation
treatment methods.
Following its recovery in October, 1982 (Figure 14), the entire hull was
sprayed with chilled fresh water. Using this method the hull was passively held
for a period of 12 years during which post-excavation recording, cleaning and
reconstruction work were completed. Throughout the period of passive stor-
age, the water temperature was maintained between 2 and 5°C. During this
period, the activity of microbes was evident and from time to time it was neces-
sary to treat the timber surfaces with a biocide due to the build up of slime (bac-
teria, fungi, diatoms and green algae). Although bacteria and fungi were found
to grow superficially on hull timbers, little active decay of the ships’ timbers
was observed. Microbes isolated from hull timbers during the passive storage
period included species of the bacteria Aeromonas,Alcaligenes,Pseudomonas
and Vibrio and fungal species identified included M. pelagica,Lulworthia
sp.,H. alopallonella,N. cristata,C. macrocephala andTricladium sp. The
optimum growth for these bacterial and fungal species isolated from hull
Conservation of Ancient Timbers from the Sea 293