Page 184 - Manual for Activities directed at the Underwater Cultural Heritage

fragile objects. Exposure to continuous fluctuation in relative humidity may even lead to the complete destruction of an object. In this way all activities related to recovery weaken artefacts’ structures and surfaces resulting in the cracking of pottery and ceramics, delaminating and crumbling of glass, shrinkage of organic materials such as wood, hemp, leather and fabric and corrosion and cracking of metals. In the short- or medium-term, this will bring about partial deterioration of the objects’ original surface, culminating in the long run in the global loss of all historical, epistemological or technical information, which could otherwise be de-rived from the object.
Principal threats to artefacts during and after recovery:
• Drying may result in the cracking and delaminating of surfaces, irreversible shrinkage, salt crystallization and mould growth;
• Increases in temperature and oxygen may result in increased speed of decay, biodegradation (algae and mould), corrosion, differential expansion and contraction;
• Increases in light exposure may result in photo oxidation, fading, accelerated decay rates, growth of green algae;
• Storing different metals together in one solution may result in galvanic corrosion;
• Insufficient physical support and poor handling may result in fractures and cracks of the structures;
• Negligence in labelling, recording.
Current professional standards
Rule 24 states that conservation shall be carried out in accordance with current professional standards. The conservation standards and ethical approaches that need to be respected in the conservation laboratories are best described as follows:
Registered interventions: all actions which are taken concerning an artefact must be registered in a reference book or database to ensure traceability of each artefact from the site to the museum, and to allow for the understanding of the long-term behaviour of materials. As far
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Conservation and site management