Range of chemical procedures to clean, preserve and stabilise artefacts from wrecks

Discuss the range of chemical procedures which can be used to clean, preserve and stabilize artefacts from wrecks and, where possible, provide an example of the use of each procedure

  • There are a range of chemical procedures that can be used to clean, preserve and stabilize artefacts that have been submerged in seawater for long periods of time, and those chosen depend on the nature of the artefact.
  • Procedures include:
    • Leaching of salts (see two above).
    • Removal of chloride by electrolysis (see two above).
    • Removal of calcium carbonate:
      • Physical removal involves sharp hits with a hammer.
      • Concretions were removed from the cannons of HMS Endeavour in this manner.
      • Chemical removal involves chemical treatment with a dilute acid, such as 1 M hydrochloric acid:
                                    CaCO3 (s) + 2H+(aq) → Ca2+(aq) + H2O(l) + CO2(g)
      • Calcium carbonate was removed in this manner from silver coins recovered from the wreck of a Dutch ship that sank off the coast of Western Australia in the seventeenth century.
    • Applying a coat of clear polyurethane polymer or micro crystalline wax.