Metals, archaeological materials

Hoffmann, P. (1989). HPLC analysis of polyethylene glycols (PEG) in wood. In I. D. MacLeod (Ed.), Conservation of wet wood and metal, Fremantle 1987 Proceedings (pp. 41-60). ICOM Committee for Conservation, Working Groups on wet organic archaeological materials and metals. 

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. 

NRA has a wide range of applications, including use in investigations of metals, glasses, and semiconductor materials, and in such diverse fields as physics, archaeology, biology, and geology. 

It seems appropriate, therefore, to begin a survey of archaeological materials with a discussion of inorganic materials - from minerals and rocks, the most abundant materials on the planet, to those extracted, derived, or made from them, such as metals and alloys, glass and ceramics (Chapters 1-7). Organic and biological materials produced by, or derived from plants or animals are discussed next (Chapters 8-15). Finally, the atmosphere and the hydrosphere, which make up most of the environment that affects all materials and determines the way they decay, are surveyed (Chapter 17). 

Perhaps the simplest archaeological question that can be answered by chemical means is what is this object made from . The chemical identity of many archaeological artifacts may be uncertain for a number of reasons. Simply, it may be too small, corroded, or dirty to be identified by eye. Alternatively, it may be made of a material that cannot be identified visually, or by the use of simple tests. An example might be a metal object made of a silvery-colored metal, such as a coin. It may be pure silver (in practice, a silver alloy containing more than about 95% silver), or it could be a silver-rich alloy that still has a silver appearance (silver coins with up to 30% copper can still look silvery, in which case the precise composition may well... 

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