Artcare - Auckland Art Gallery

Bone / Ivory / TeethAlthough bone, ivory and teeth differin colour, grain, texture and hardness,their chemical composition issimilar and they react in a similarmanner to different environments. Allconsist primarily of inorganic materialswhich provide rigidity andstrength, and an organic component,which has the capacity for growthand repair. The difference is thatbone has tiny blood vessels whichextend through a central spongy marrow,and ivory and teeth have noblood marrow or blood vessel system. Ivory and teethare usually harder, denser and whiter than bone.These materials have been used to make a variety ofartefacts including tools, weapons, jewellery and paintingsupports.Causes of DeteriorationAll of these materials are reasonably durable, althoughthey can be easily damaged if improperly cared for.Bone, ivory and teeth, like wood, are hygroscopicmaterials. This means that they will absorb and releasemoisture with fluctuations in humidity, swelling orshrinking as the humidity levels change. Fluctuationssuch as these can cause severe cracking and warpingand, in particular, affect ivory objects such as supportsfor miniatures. It is therefore important that steadyhumidity and temperature levels aremaintained and extreme conditionsavoided. These materials should bekept away from direct sunlight, hotlight sources, strong air currents,exterior walls or windows.Bone, ivory and teeth are alsovery susceptible to staining from sulphur,metals and coloured materials.HandlingGloves should be worn when touchingthese materials. Fragile materialshould be supported on padded blocks so that movementis possible without any direct handling of the objectitself.Display and StorageStrong light, particularly daylight, should not be present.When considering mounts for display purposes, rubberpads and adhesives should not be used near ivory as thesulphur can cause stains. Similarly, contact with iron,copper alloys and coloured materials should be avoidedbecause they too can stain. Ivory supports for miniaturepaintings should not be glued down to backings; thiswill cause stress as the support tries to adjust to differingtemperatures and humidity changes and could leadto cracking. Storage and display areas should be wellventilated.46