Ivory carving

Ivory carving

Ivory carving is the carving of ivory, that is to say animal tooth or tusk, by using sharp cutting tools, either mechanically or manually. The ancient craft has now virtually ceased, as since CITES it is illegal under most circumstances throughout the world....

 is a decorative art

Decorative art

The decorative arts is traditionally a term for the design and manufacture of functional objects. It includes interior design, but not usually architecture. The decorative arts are often categorized in opposition to the "fine arts", namely, painting, drawing, photography, and large-scale...

 or craft

Craft

A craft is a branch of a profession that requires some particular kind of skilled work. In historical sense, particularly as pertinent to the Medieval history and earlier, the term is usually applied towards people occupied in small-scale production of goods.-Development from the past until...

 practised since prehistoric times. Its conservation is concerned particularly with the environmental causes of deterioration.

Ivory

Ivory

Ivory

Ivory is a term for dentine, which constitutes the bulk of the teeth and tusks of animals, when used as a material for art or manufacturing. Ivory has been important since ancient times for making a range of items, from ivory carvings to false teeth, fans, dominoes, joint tubes, piano keys and...

 is the term for the tusks and teeth of mammals including the elephant

Elephant

Elephants are large land mammals in two extant genera of the family Elephantidae: Elephas and Loxodonta, with the third genus Mammuthus extinct...

, hippopotamus

Hippopotamus

The hippopotamus , or hippo, from the ancient Greek for "river horse" , is a large, mostly herbivorous mammal in sub-Saharan Africa, and one of only two extant species in the family Hippopotamidae After the elephant and rhinoceros, the hippopotamus is the third largest land mammal and the heaviest...

, warthog

Warthog

The Warthog or Common Warthog is a wild member of the pig family that lives in grassland, savanna, and woodland in Sub-Saharan Africa. In the past it was commonly treated as a subspecies of P...

, wild boar, walrus

Walrus

The walrus is a large flippered marine mammal with a discontinuous circumpolar distribution in the Arctic Ocean and sub-Arctic seas of the Northern Hemisphere. The walrus is the only living species in the Odobenidae family and Odobenus genus. It is subdivided into three subspecies: the Atlantic...

, narwhal

Narwhal

The narwhal, Monodon monoceros, is a medium-sized toothed whale that lives year-round in the Arctic. One of two living species of whale in the Monodontidae family, along with the beluga whale, the narwhal males are distinguished by a characteristic long, straight, helical tusk extending from their...

, and mammoth

Mammoth

A mammoth is any species of the extinct genus Mammuthus. These proboscideans are members of Elephantidae, the family of elephants and mammoths, and close relatives of modern elephants. They were often equipped with long curved tusks and, in northern species, a covering of long hair...

. Elephant ivory comprises up to 55% inorganic

Inorganic compound

Inorganic compounds have traditionally been considered to be of inanimate, non-biological origin. In contrast, organic compounds have an explicit biological origin. However, over the past century, the classification of inorganic vs organic compounds has become less important to scientists,...

 matter - mainly calcium phosphate

Calcium phosphate

Calcium phosphate is the name given to a family of minerals containing calcium ions together with orthophosphates , metaphosphates or pyrophosphates and occasionally hydrogen or hydroxide ions ....

, as well as magnesium phosphate

Magnesium phosphate

Magnesium phosphate is a general term for salts of magnesium and phosphate appearing in three forms:* Magnesium phosphate monobasic * Magnesium phosphate dibasic * Magnesium phosphate tribasic...

 and calcium carbonate

Calcium carbonate

Calcium carbonate is a chemical compound with the formula CaCO3. It is a common substance found in rocks in all parts of the world, and is the main component of shells of marine organisms, snails, coal balls, pearls, and eggshells. Calcium carbonate is the active ingredient in agricultural lime,...

 - the remainder consisting of the organic

Organic matter

Organic matter is matter that has come from a once-living organism; is capable of decay, or the product of decay; or is composed of organic compounds...

 protein

Protein

Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

 dentine.

Deterioration

Ivory is hygroscopic and anisotropic, tending to shrink, swell, crack, split, and/or warp on exposure to extremes or fluctuations in relative humidity

Relative humidity

Relative humidity is a term used to describe the amount of water vapor in a mixture of air and water vapor. It is defined as the partial pressure of water vapor in the air-water mixture, given as a percentage of the saturated vapor pressure under those conditions...

 and temperature

Temperature

Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...

, It is subject to photolytic

Light

Light or visible light is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz...

 colour change. Its organic compounds decompose by hydrolysis

Hydrolysis

Hydrolysis is a chemical reaction during which molecules of water are split into hydrogen cations and hydroxide anions in the process of a chemical mechanism. It is the type of reaction that is used to break down certain polymers, especially those made by condensation polymerization...

 with prolonged exposure to water, while its inorganic compounds are attacked by acids. Deteriorated ivory in particular is porous, brittle

Brittle

A material is brittle if, when subjected to stress, it breaks without significant deformation . Brittle materials absorb relatively little energy prior to fracture, even those of high strength. Breaking is often accompanied by a snapping sound. Brittle materials include most ceramics and glasses ...

, and prone to impact damage and delamination

Delamination

Delamination is a mode of failure for composite materials. Modes of failure are also known as 'failure mechanisms'. In laminated materials, repeated cyclic stresses, impact, and so on can cause layers to separate, forming a mica-like structure of separate layers, with significant loss of mechanical...

. Many conservation problems are caused by previous conservation treatments such as incompatible and degraded coatings, adhesives, and attempts at reconstruction.

Technical examination

Inspection in visible and ultraviolet

Ultraviolet

Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...

 light

Light

Light or visible light is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz...

, optical microscopy, x-radiography, and scanning electron microscopy to reveal cell

Cell (biology)

The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....

 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

Polychrome

Polychrome is one of the terms used to describe the use of multiple colors in one entity. It has also been defined as "The practice of decorating architectural elements, sculpture, etc., in a variety of colors." Polychromatic light is composed of a number of different wavelengths...

 ivories, as well as undocumented conservation materials from previous interventions.

Preventive conservation

Ivory should be stored and displayed out of direct sunlight

Insolation

Insolation is a measure of solar radiation energy received on a given surface area in a given time. It is commonly expressed as average irradiance in watts per square meter or kilowatt-hours per square meter per day...

 and away from sources of heat. Inert display cases may be used to buffer

Buffer

Buffer may refer to:*Buffer state, a country lying between two potentially hostile greater powers, thought to prevent conflict between them* Buffer zone, any area that keeps two or more other areas distant from one another, may be demilitarized...

 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.

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

Reversibility

Reversibility can refer to:* Reversible dynamics, a mathematical dynamical system, or physical laws of motion, for which time-reversed dynamics are well defined* Reversible diffusion, an example of a reversible stochastic process...

 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.