Page 190 - Manual for Activities directed at the Underwater Cultural Heritage

The degree of hardness
and the nature of the object
will determine which cleaning methods will be used: mechanical (micro-sandblaster, micro-chisel, scalpel), chemical (immersion),
a combination of the two or electrochemical. Electrochemical cleaning treatments involve cathodic polarization for metal (conductive) objects and electrophoresis for organic and other non-conductive materials. Electrolysis is used to remove chlorides and surface corrosion from non-conductive organic materials and occasionally ceramics, cannons, anchors and other large archaeological objects. Sometimes a concretion contains only a hollow space, which once contained an object that has rusted away.Thus it is important not to crack it. Such a hollow can be cast by filling it with epoxy, recalling and ‘saving’ the object’s original form.
© Ships of Discovery. Prospecting during the Slave ShipTrouvadore Project: James Hunter examining the hull remains of the Black Rock Wreck (the so-called slave ship Trouvadore) sunk in 1841 in the Turks & Caicos Islands, British Overeas Territories, United Kingdom.The conservation process starts well before intervention with prospection and preparative work. During prospection, underwater archaeologists undertake some preparatory dives and sampling
to obtain a good understanding
of the nature, number and type
of artefacts that are likely to be discovered and that will thus need to be conserved.This data will allow them to prepare the conservation programme as part of the project design. 
conservation should be distinguished from those related to curative conservation and restoration.
During intervention
• Preventive conservation on site
During archaeological work, as soon as sand and/or silt is removed from the site, the natural physical and chemical equilibrium between the artefacts and the bed in which they lie is changed and the degradation process (re)starts. Therefore, objects should not be removed until secure arrangements are made to conserve them properly, especially if objects are taken out of the water.
The first steps of preventive conservation are emer- gency measures, like the first aid that a soldier receives from a doctor on a battlefield. It is about insuring perpetuity and integrity to the collection, but also about guaranteeing accessibility. At this stage, all artefacts need to be given the same attention. Limitation to only valuable artefacts based on the quality of the material or the good condition of conservation, increases the serious risk of neglecting other items that do not originally seem important, but may later reveal essential information following proper conservation and restoration.
Preventive conservation work has to be framed within the same professional standards that are applied in full conservation and restoration. Interventions
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Conservation and site management