Conservation and restoration of ivory objects

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Ivory carving is a decorative art or craft practised since prehistoric times. Its conservation is concerned particularly with the environmental causes of deterioration.

Ivory

Ivory is the term for the tusks and teeth of mammals including the elephant, hippopotamus, warthog, wild boar, walrus, narwhal, and mammoth. Elephant ivory comprises up to 55% inorganic matter - mainly calcium phosphate, as well as magnesium phosphate and calcium carbonate - the remainder consisting of the organic protein dentine.[1][2]

Deterioration

Ivory is hygroscopic and anisotropic, tending to shrink, swell, crack, split, and/or warp on exposure to extremes or fluctuations in relative humidity and temperature, It is subject to photolytic colour change. Its organic compounds decompose by hydrolysis with prolonged exposure to water, while its inorganic compounds are attacked by acids. Deteriorated ivory in particular is porous, brittle, and prone to impact damage and delamination. Many conservation problems are caused by previous conservation treatments such as incompatible and degraded coatings, adhesives, and attempts at reconstruction.[2][3][4]

Technical examination

Inspection in visible and ultraviolet light, optical microscopy, x-radiography, and scanning electron microscopy to reveal cell structure, may be used to identify the species used, advance understanding of the techniques employed by the craftsman, and reveal deterioration phenomena. Instrumental analysis may also be used to identify pigments and binders for polychrome ivories, as well as undocumented conservation materials from previous interventions.[4][5]

Preventive conservation

Ivory should be stored and displayed out of direct sunlight and away from sources of heat. Inert display cases may be used to buffer against environmental fluctuations. Lighting levels should also be limited, especially for polychrome ivories. Ivories should be protected against contact with liquids and other staining materials[3][4] such as corroded metals.[6]

Intervention

Especially in archaeological contexts, interventive treatment may in some cases be considered necessary. Such intervention is governed by conservation ethics, in particular the principles of reversibility and minimum intervention. Possible treatments include the reduction of salts to prevent further deterioration, and the consolidation of delaminating and friable components. Any treatment should be undertaken by a conservation professional.[2][3][4]

See also

References

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  4. ↑ 4.0 4.1 4.2 4.3 Lua error in package.lua at line 80: module 'strict' not found.
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  6. ↑ Care of Ivory, Bone, Horn, and Antler, Canadian Conservation Institute

Further reading

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  • Starling,K.(Ed.) Archaeological bone, antler and ivory, London 1987.
  • Cristoferi,E. Gli Avori:Problemi Di Restauro,Firenca 1992.
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