Silver artifact

The second study was designed to contribute to the current focus on the protection of silver artifacts by electrochemically grown poly-3-amino 1,2,4-triazole (PAta) [304], There is evidence that the dissolution of a silver copper alloy is inhibited by Ata adsorption with interaction with oxidation species (see Fig. 6.3). 

ICP-MS has also been used to measure trace elements in archaeological native silver artifacts [345] in order to identify their geographical origins. The low detection limits provided by ICP-MS allowed analysis of trace elements on 3 to 15 mg of sample. The passivation of alloy steels using acid solutions has been studied by XPS measurements of the solid in combination of ICP-MS analysis of the passivation solutions [346,347]. When bullets are crushed on impact, striations cannot be used for identification. The percentage of antimony, trace element composition, and lead isotope ratios in bullets was measured for forensic evidence [348]. The lead isotope ratios were found to be the most useful evidence. 

Figure 5. Lead isotope compositions of Early Cycladic lead and silver artifacts.

Radiographic studies on more than 100 Sasanian silver artifacts and an equal number of related silver objects strongly indicate that the Sasanian silversmith used hammering exclusively as the major shaping technique for all his objects. Among vessels accepted as genuine Sasanian, none were found that appeared to have been made by the double shell technique or that could be positively identified as cast. 

Reedy, C. L., Long, D. L., Corbett, R. A., Tatnall, R. E., et al. (1999). Evaluation of three protective coatings for indoor silver artifacts. In Objects Specialty Group postprints (pp. 41-69), 6. American Institute for Conservation. 

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. 

Of all the ancient metallic artifacts that have been left from antiquity, coins are among the most numerous. Since ancient times coins have generally been made from coinage metals or, mostly, from coining alloys, whose chemical and physical properties and economic qualities make them suitable to be used for this purpose. Until the twentieth century, gold, silver, copper, and their alloys were practically the only metals from which coinage was made. All these metals and alloys have the following properties ... 

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... 

Linke, R. and Schreiner, M. (2000). Energy dispersive X-ray fluorescence analysis and X-ray microanalysis of medieval silver coins - an analytical approach for non-destructive investigation of corroded metallic artifacts. Mikrochimica Acta 133 165-170. 

Careful sample handling is important when sensitive detection methods are employed. Silver-stained SDS-PAGE gels sometimes show artifact bands in the 50- to 70-kDa molecular mass region and irregular but distinctive vertical streaking parallel to the direction of migration. The appearance of these artifacts has been... 

Degrigny C (1995) Stabilisation de moteurs d avion immerges. Stud Conserv 40 10-18. Organ RM (1967) The reclamation of the wholly mineralized silver in the Ur lyre. In Application of Science to Examination of Works of Art, Museum of Fine Arts, Boston, 126-144. Degrigny C, Le GaU R (1999) Conservation of ancient lead artifacts corroded in organic acid environments electrolytic stabilization/consolidation. Stud Conserv 44 157-169. 

In contrast to the case for copper, for silver a reduction of the tarnish rate by circa 100-fold has been observed as tarnish layers increase (Graedel et al., 1985), thus indicating that to a degree, the tarnish layers themselves impede further tarnishing. It is known that major silver tarnish can occur at concentrations of circa 100pptv and it has been shown that in effect it is the sum of OCS and H2S along with artifact reactivity, which determines the tarnish rate (Ankersmit, Tennent and Watts, 2005). 

Figure 11 FTIR spectra obtained ex situ from silver electrodes treated in PC + 0.2 M LiAsF6 solutions, (a) Thin layer of solvent on a silver plate, (b) Electrode removed from solution after the potential was swept from OCV (around 3 V) to 1.5 V (Li/Li+). (c) Electrode removed from solution after the potential was swept from OCV to 0.5 V (Li/Li+). ( ) Artifact resulting from atmospheric C02 subtraction (present in the spectrometer cavity at slightly different concentrations during the sample and reference measurements) [12]. (With copyrights from Elsevier Science Ltd.)...

A promising approach to this problem has been the use of lead isotope ratios to characterize sources. Chapter 9 by Gale and Stos-Gale is an example of this type of study. The isotopic ratios of lead are variable because some of the isotopes are the daughters from the radioactive decay of uranium and thorium (4), Even though the amount of lead in bronze artifacts is small, Gale has been able to distinguish between sources of the ore on the basis of the ratios of the various lead isotopes. The sources of silver, lead, and copper in the Bronze Age Mediterranean are discussed. 

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