154 ARCHAEOLOGICALCONSERVATION ANDFIRST-AID FORFINDS
and those incorporating glass, ivory, jet, shale,
amber, leather or textile, should be referred to a
conservator immediately if possible.The process of the removal of seawater should not
be confused with that of ‘desalination’. The removal of
seawater entails replacement using a number of baths of
fresh water immediately on recovery, thereby helping to
remove potential chemical and biological reactants. All finds
should be constantly monitored. In most cases robust mater-
ials should be transferred into fresh water immediately
on recovery, with the first two to three baths consisting,
perhaps, of a 50 per cent dilution using fresh water and
each bath lasting 30 minutes to 2 hours. Thereafter,
changes of water should be aimed at ‘desalination’ (the
removal of salts held deep within the interstices of
objects), a process that may take many weeks or months
to achieve, during which time most materials should,
ideally, have been submitted for archaeological conserva-
tion. Initial baths for desalination might consist of a
50 per cent dilution using fresh water, with each bath
lasting perhaps 6 – 8 hours, carried out over 2– 4 days, with
regular changes every 4 – 6 days thereafter.
Arrangements for the slow movement of water
through large storage tanks may help to alleviate the
build-up of mould growth, algae and biological ‘slimes’.
Very vulnerable materials, such as composite objects or
those made of organic materials, may require slower lev-
els of dilution, as they may be subject to collapse under
‘osmotic pressure’, although this may be somewhat rare.
Once again, if in doubt, conservation advice should be
sought at the earliest opportunity.
Damp artefacts (i.e. those neither waterlogged nor
dry), sometimes found in deep sea-bed deposits and
some of the most vulnerable to damage post-excavation,
should be kept in conditions as similar as possible to the
original context. They should be recovered in associated
deposits and be kept damp rather than topped up with
water but should not be allowed to dry out. Small quan-
tities of water from the burial environment can be used
in packing. All damp material should be ‘double-bagged’
in self-seal polyethylene bags and/or packed in lidded boxes
with air excluded, refrigerated and sent for conservation
and/or analysis as soon as possible (preferably within
24 – 48 hours following recovery). Materials and procedures
for recovery should be checked with relevant specialists.
LIFTING, HANDLING AND TRANSPORTATION
The lifting, handling and transportation of artefacts is often
complex and likely to require pre-planning and adapta-
tion to suit the needs of specific projects. The approaches
adopted may vary depending on a number of factors,
including fragility, significance, location, size and mass
of artefacts, project objectives, timescales, resources
and arrangements for conservation. All team members
should have a good understanding, in advance, of the
systems and methodology to be used, and details of con-
servation facilities and environmental scientists to be
consulted in relation to the retrieval of large or complex
finds and structures.
When excavating material, all finds should be completely
uncovered and exposed from the burial context prior
to lifting, unless retention of the context (surrounding
sediments or deposits) is important. Many waterlogged
objects may appear to be robust despite being physically
weak. Thus, pulling on, or attempting to lift an object
where one end is still embedded, may cause it to snap.
This applies equally to large objects (such as cannon) as
to small finds. Finds that appear to extend downwards,
and therefore, through several layers of context, should
be discussed in advance. Their removal may often involve
a compromise. For example, partially exposed wooden
structures may be subject to environmental damage,
while complete removal may leave holes in surrounding
stratigraphy, with possible subsequent destabilization
of the area.- Finds should be moved slowly under water because
the pressure exerted by the water may cause phys-
ical damage. - Suitable procedures should be planned for the
recovery of finds in the event that decompression
stops are necessary. - All strops on air-lifting bags should be cushioned
at points of contact with finds using soft, inert
materials. The numbers of points should be as
extensive as possible in order to spread the load and
avoid the creation of pressure points. - Storage bins and containers of the appropriate
size should be present on dive platforms, boats or
barges, or the shore base.
Methods of support for finds during excavation and
lifting, particularly those unable to support their own
weight (figure 16.5), include the following (which may
be combined):- Flat sheets, such as inert seasoned wooden plank-
ing, steel baking-trays or polyethylene box-lids (all
of which should be removed once the object is in
storage). - Self-seal plastic bags, which are useful for incor-
porating water and/or burial sediment from sur-
rounding contexts (which may provide additional
cushioning). The bags should not be too full of water
and all air should be excluded on sealing.