Archaeology Underwater: The NAS Guide to Principles and Practice

152 ARCHAEOLOGICALCONSERVATION ANDFIRST-AID FORFINDS

PRINCIPAL RISKS TO FINDS DURING AND

AFTER RECOVERY

Removal of finds from their burial context is likely to cause
extensive changes, as outlined in the list below:

• Drying may result in cracking, delamination of
  surfaces, irreversible shrinkage, salt crystallization and
  potential mould growth.


• Increased temperatures and oxygen access may lead
  to increased speeds of decay, biodegradation (algae
  and mould growth, often turning finds ‘green’) and
  corrosion, and/or may initiate new corrosion reac-
  tions in metals. Changes in temperature may cause
  differential expansion and contraction, leading to
  damage, particularly in composite objects.


• Increased light may lead to photo-oxidation, fading
  and increased decay rates, promoting the growth of
  green algae.


• Storage of different types of metals in solution
  together may result in galvanic corrosion (with
  increased corrosion reaction rates).


• Poor handling or lack of physical support may
  result in changes to centres of gravity, in turn lead-
  ing to cracks or fractures.


• Lack of attention to labelling and monitoring of
  storage water levels is likely to result in the loss of

context and, therefore, any meaningful archaeolog-

ical information.

These can be mitigated, to some extent, by using

appropriate ‘first-aid’ procedures.

PRINCIPLES AND PROCEDURES FOR FIRST-AID

FOR UNDERWATER FINDS

The importance of good planning, attention to detail, high-

standard recording and the proper care and supervision

of finds, both during and after excavation, cannot be

overemphasized. Overall approaches to ‘first-aid’ provi-

sions for finds (Robinson, 1998) within any project may

need to be tailored according to:

• the predicted nature of the material to be recovered;


• the potential size of an assemblage; and


• planning for the recovery of large or bulky archae-
  ological structures.

A ‘first-aid’ field facility should provide suitable

storage for recovered finds (plate 16.2) whereas full con-

servation treatment should be undertaken in a fully

equipped conservation laboratory, in which conditions

are more easily controlled and where material may be

Figure 16.2 A concretion recovered
from the Duart Point wreck (1653)
site, Mull, Scotland. (Photo: Colin
Martin)

Figure 16.3 An X-ray of the con-

cretion shown in figure 16.2 shows

that it contains an elaborate sword

hilt. (Courtesy of the Trustees of the

National Museums of Scotland)

Figure 16.4 The Duart Point sword

hilt shown in figures 16.2 and 16.3,

after conservation. (Photo: Colin Martin)