Objects archaeological

Early scientific studies were ptedominandy aimed at objects often referred to as belonging to the fine arts. Subsequendy, equal importance and effort has been attached to studies of objects of cultural and historical interest, such as archaeological and ethnographic materials, or manuscripts, documents, photographs, and books in archives andUbraries. This article is meant to be inclusive of all such objects as well as of fine arts objects. The term art object when used is an inclusive, generic connotation rather than an exclusive one. 

Trace-element analysis, using emission spectroscopy (107) and, especially, activation analysis (108) has been appHed in provenance studies on archaeological ceramics with revolutionary results. The attribution of a certain geographic origin for the clay of an object excavated elsewhere has a direct implication on past trade and exchange relationships. 

Deteriora.tlon. Apart from physical damage that can result from carelessness, abuse, and vandaUsm, the main problem with metal objects Hes in thek vulnerabihty to corrosion (see Corrosion and corrosion control) (127,128). The degree of corrosion depends on the nature and age of the object. Corrosion can range from a light tarnish, which may be aesthetically disfiguring on a poHshed silver or brass artifact, to total mineralization, a condition not uncommon for archaeological material. 

On archaeological glass objects, layers of reaction products are formed and the main constituents of these cmsts are the less-soluble compounds such as siHca and calcium carbonate, which becomes calcium sulfate. 

Clearly, the intended use of a collection item is extremely important to determining the acceptabiHty of a treatment. The degree to which a treatment affects appearance is obviously of the greatest importance for an art object. On the other hand, in natural history collections the collections serve as research resources above all. The effect a preservation or conservation treatment has on these research appHcations is the main consideration. Collections of art, archaeology, history, science, technology, books, archival materials, etc, all have their own values in terms of balance between preservation needs and collections use, and these values are, moreover, constantly subject to reevaluation and change. 

The constant half-life of a nuclide is used to determine the ages of archaeological artifacts. In isotopic dating, we measure the activity of the radioactive isotopes that they contain. Isotopes used for dating objects include uranium-238, potassium-40, and tritium. However, the most important example is radiocarbon dating, which uses the decay of carbon-14, for which the half-life is 5730 a. 

Applications The main application fields of PIXE are earth science, air pollution studies (aerosol analysis), mineralogical studies, forensic science, arts and archaeology. In the external-beam PIXE technique, the proton beam is taken out to ambient air. This mode finds application in the analysis of art objects (paintings, books, etc.). 

If thick samples are placed in the specimen chamber for analysis, the particles are slowed down and eventually stopped in the sample, so the calculation of the X-ray yield and their absorption is more complicated. Some objects may be too large to be placed in the specimen chamber, in which case the external beam technique is employed. The particle beam passes through a window at the end of the beam-line into the air where an object of any size (e.g. an archaeological artefact) may be analyzed. 

For the analysis of large objects which cannot be placed within the irradiation chamber it is possible take the particle beam into the ambient air through a thin window at the end of the beam line. In this way any type of object can be analysed -for example paintings and archaeological artefacts. 

In many instances when analyzing archaeological objects, removing a sample may be aesthetically deleterious to the object, therefore rendering the removal of samples totally inadequate, or allowing the removal of extremely small samples so as not to affect the appearance of the objects. In such cases it is often necessary to turn to specialized techniques, such as nondestructive techniques, which do not require the removal of samples altogether, or to micro analytical techniques, for which extremely small samples are needed (see Textbox 11). 

The environment has negative effects on most metals thus, when metallic archaeological objects are eventually found, they are generally in an advanced state of decay. The decay of metals and alloys caused by the chemical action of gases and/or liquids in the environment is known as corrosion. Corrosion processes are natural destructive processes that result in the waste of most metals and alloys. The ultimate result of all corrosion processes is the reversion of most metals from the metallic condition in which they are used, to the chemically combined form in which they naturally occur in the crust of the earth. Rust, the reddish-brown corrosion product that forms on... 

Most ancient wooden objects recovered in archaeological excavations are usually in a decayed, weak, and friable condition that requires stabilization before the objects can be safely handled and studied. Stabilization of wood and decayed wooden objects, generally includes the use of consolidants, liquid solutions of a resin that impregnates and fills gaps in the wood and on drying solidifies, strengthening its fragile, deteriorated structure (Thompson 1991 Rowell and Barbour 1990). 

Efflorescence. The solvent properties of water also causes efflorescence, a phenomenon whereby soluble or slightly soluble substances migrate from the interior of porous solids to the surface, where they precipitate. Efflorescence is an important factor in the decay and disintegration of many rocks, and of human-made porous materials such as ceramics, and even of some types of glass. On archaeological objects, efflorescence generally occurs mostly as a white, powdery, but sometimes consolidated accretion on the surface of the objects. Calcite, a form of calcium carbonate, is one of the most common substances to effloresce on archaeological ceramics. 

The atmosphere is a reservoir of aggressive air pollutants that may cause serious deterioration to archaeological objects some of the most active pollutants are sulfur dioxide, hydrogen sulfide, and ozone. 

When ancient objects are removed from their original archaeological location, they lose much of their initial value to the scholar, since site, position, and surroundings convey a great deal of information about an object and also enable its authentication. Authenticating isolated objects relies on the fact that antiquities carry within themselves evidence of the time and place of their manufacture (Jones 1992 Jaffe and Van der Tweel 1979). 

Many material properties lend themselves to the authentication of objects the composition and the physical and chemical properties of materials and their decay products provide objective criteria for establishing the authenticity of archaeological objects. Contradictions between the claimed origin or... 

Kuleff, I. and M. Djingova (1990), Activation analysis of archaeological and art objects, in Alfassi, Z. (ed.), Activation Analysis, Chemical Rubber Company, Boca Raton, FL. 

Norton, N. A. Conservation of metals, in Pearson, C. (eds.), Conservation of Marine Archaeological Objects, Butterworth, London, pp. 207-252. 

Pernicka, E. (2004), Archaeometallurgy Examples of the application of scientific methods to the provenance of archaeological metal objects, Proc. Int. School of Physics "Enrico Fermi," Vol. 154, Physics Methods in Archaeometry, pp. 309-329. 

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