One's first contact with materials occurs as infants with the swaddling cloths that warm and comfort us, but also restrain us. As life goes on material objects always surround us. They structure the way we look at the world and how we arrange our thoughts; they serve a wide range of utilitarian, aesthetic, social and symbolic functions; methods of designing, manufacturing and using materials are at the core of our technology and much of our culture. Materials technology, making and using objects, is thus in a unique position relative to history and culture. While interpretations sought by study of these objects are judgmental and humanistic, they must rest on as secure a foundation of solid materials knowledge as is possible. The central paradigm of materials technology is that the selection and processing of materials gives rise to a particular structure which is the source of useful properties (Fig. 1). This is exactly the process used by the artist who aims at aesthetic properties, and the craftsman and technologist who aim at particular properties.

Excavated metals, some with secure dates as early as the eighth millennium BC, have been analyzed using a variety of scientific methods in order to provide insight into early metallurgical technology. The results are often used to reconstruct the role of technology in the social structure of the community. This lecture will review many of these methods giving examples from the examination of excavated objects.

In the areas of archaeology, archaeometry, museum management and conservation science conflict often exists between the desire to preserve, and the desire to understand an artifact. This conflict exists because much laboratory analysis can be destructive. However, conservation can best be done when the materials and techniques that were used for making the object originally are understood. Thus there is a constant drive to develop non-destructive and/or microsample analysis procedures that are meaningful in terms of the statistical accuracy of the results and the added understanding that they provide. In addition to the availability of new microanalytical techniques, the scientific approach developed in materials science is of great value to the fields of archaeometry and conservation science. The ‘materials science approach’ involves the determination of structure and chemistry at various levels in the microstructural hierarchy, and includes the relationship between this structure and chemistry and the material's properties. On the other hand, the study of archaeological materials can be of great value to the materials scientist because these objects exist in a time frame not reproduceable in typical laboratory experiments.

Results of non-destructive analyses of solders on gold jewelry artefacts involving the irradiation of the material with protons and the prompt detection of X-ray signals allow us to understand the joining procedures used by ancient goldsmiths.

A non conventional interpretation of the Natural History (33th Book) of Elder Pliny (1st cent. A.D.) concerning chrysocolla (or goldsolder) sheds some light on the present debate around the possible use (in antiquity) of greenockite (natural CdS) as an alloyed element with gold to achieve low melting point brazing.

The cauldrons and buckets of the later Bronze Age in Atlantic Europe, produced from the 12th to the 6th century BC, were some of the most complex fabrications made in that period of prehistory. They show a steadily increasing understanding of the problems posed by their design and an increasing elegance in their solution. At the same time they demonstrate considerable awareness of materials properties and provide one of the clearest instances in the Bronze Age of materials selection for specific purposes.

In recent years the research potential of museum collections has come to be more widely recognized by anthropologists [1]. There are a number of factors that account for a turn from collecting “primary” data towards an approach based on reevaluating material remains collected by another. Prehistoric archaeologists have often led the way in artifactual analysis because the physical artifact is our only means of reconstructing past lifeways. Although sane have argued that this limitation in our range of data does not limit the possibilities of ultimate reconstruction [2], nevertheless it is with the artifact that we must begin.

Since the seminal work of Friedman and Smith [1] obsidian hydration dating (OHD) has undergone several important stages of development and refinement. This paper will summarize the history of research and developments as to elucidate some areas for future research.

Archaeologists have taken a pragmatic and empirical approach towards OHD and hydration rate determination. They would like OHD to become an absolute chronometric technique. Geochemists and material scientists have sought to understand the hydration process from an environmental, chemical and thermodynamic perspective. As suggested by the literature, obsidian hydration appears to be a diffusion, reaction and dissolution process dependent on the chemical and thermal history of the hydration environment. Although there appear to be certain central tendencies, however, there are discrepancies between empirical archaeologically-derived data and theoretical models.

California offers a rich data base for synthesis and testing of hydration models. There are over 25 natural obsidian sources many of whose chemical and physical properties have been measured by Ericson [2]. Obsidians have been distributed aboriginally as artifacts into diverse environments. Intensive excavations, underwritten by extensive land development, have contributed to development of a number of source-specific hydration rates for single sources. Reanalysis of the California data warrants future examination to advance our understanding of obsidian hydration dating on a world wide basis.

Chemical analysis of typical obsidians place them with a group of silica- and alumina-rich glasses constructed of a three dimensional framework of silica and alumina tetrahedra with nearly all tetrahedra sharing corners. Raman and infrared spectra of unweathered obsidians confirm the high degree of polymerization as well as some additional structural disorder. Analysis of dissolution rates of various glasses shows obsidian to be among the most stable, comparable to the most durable synthetic glasses. Surface layers on glasses can be chemically characterized by depth-profiling techniques such as SIMS and SIPS that give depth-concentration profiles for individual elements. Hydration rinds on glasses can be structurally characterized by infrared spectroscopy which shows both hydration and re-polymerization as the rinds age. Because obsidians are already completely polymerized glasses, their hydration rinds are mainly a result of hydrolysis and alkali exchange.

The results of a series of hydration experiments on natural glasses (Hawaiian basalt, obsidian) and the nuclear waste glass WV-44 done to examine laboratory methods of accelerating reaction processes are summarized. The glasses were reacted in hydrothermal solution and in saturated vapor water. It was found that different reaction rates and processes were found using the differing conditions, and that laboratory efforts to accelerate and duplicate natural processes must account for the physical processes that occur naturally.

The rate of many processes, including the diffusion of water into rhyolitic volcanic glass (obsidian), as well as the racemization of amino acids is temperature dependent, and a knowledge of temperatures integrated over time periods of at least a year is necessary to quantify these processes. The construction and properties of simple devices consisting of small plastic containers that change weight at a rate that is a function of temperature and the activity of water will be described. The cells function because water diffuses through the plastic across a constant vapor-pressure gradient. This vapor-pressure gradient is maintained constant between the substances within the cell and the materials outside the cell. The plastic cells are usually filled with water and surrounded by a dehydrating agent, such as silica gel. A better arrangement is to fill the cell with a mixture of solid sodium chloride (NaCl) and a saturated solution of NaCl, and to surround the cell with pure water. A number of plastics have been investigated, including polycarbonate, polystyrene, tefzel, polyallomer, and methacrylate. The cells have been sealed by various methods including screw caps, room-temperature vulcanizingsilicone rubber sealant, and rubber stoppers. The final design consists of a small cell made of a polycarbonate plastic centrifuge tube containing solid NaCl plus NaCl-saturated solution sealed with a rubber stopper and placed in a polypropylene tube containing pure water. Our aim has been to develop cells that are sufficiently sensitive to yield a precision of ±0.2° C when exposed for one year at temperatures that range from 0° to 40°, and that will fit into metal fittings that can be screwed into standard 3/4-inch plastic water pipe (approximately 1 inch outside diameter).

Various theoretical models that have been proposed to correlate glass durability to their composition for a wide variety of silicate, borosilicate, and aluminosilicate glasses are examined. Comparisons are made between the predictions of these models and those of an empirical formulation extracted from existing data in the present work. The empirical approach provides independent confirmation of the relative accuracy of the silica release rate predictions of the different theoretical models in static leaching systems. Extensions of the empirical approach used in this work are discussed.

Hydration rind thicknesses found on obsidian artifacts provide one means of estimating the age of an archaeological site. The model used in the method usually assumes a diffusion-controlled reaction of the glass with water. However, results using this model are not always in agreement with other dating methods. Observations of secondary mineral formation on glasses in contact with water vapor suggests that other rate-controlling mechanisms may be operative. In this paper, we apply the glass dissolution code GLASSOL, coupled with the geochemical code PHREEQE to model the reaction of Glass Mountain obsidian in water. The results show the importance of accounting for the effects of solution chemistry on the time-dependence of the hydration reaction.

Induced obsidian hydration experiments have been conducted over the last six months at Sonoma State University. Our initial focus has been to assess the influence of experimental conditions on hydration development within a thermally controlled pressure reaction vessel. Although an ultimate goal is to calculate source-specific rates for local obsidians, given current uncertainties regarding the ability to reliably express hydration widths as calendar years, a more immediate goal is to develop a means to compare hydration rim measurements of samples from one obsidian source relative to another so that archaeological assemblages containing obsidians from two or more sources can be placed into a time series. Induced hydration experiments are expected to provide data that illustrate the relationship between hydration measurements of different obsidians with temporal equivalency. Results and implications of initial experiments are discussed.

Samples of wet 13th-14th c. Grisaille window glass, visually sorted according to their extent of corrosion, were examined for physical changes while air-drying and solvent-drying. Polished cross-sections of the samples were examined with a JEOL-35CF SEM with a LINK AN 10,000 dispersive x-ray analyzer. Elemental distribution maps showed distinct alterations in the positioning of elements according to the corroded nature of the glass.

As part of a project sponsored by the Getty Conservation Institute to investigate the effects of humidity and temperature on photochemicallyinduced deterioration, the influence of relative humidity on the rates of fading of four traditional artists' pigments has been investigated -- carmine lake, gamboge, alizarin lake and Vandyke brown.

Although an extensive type of salinization of ancient Egyptian temples has been recognized as early as 1977, and although the general mechanism of salinization has been proposed and verified by computer modelling in 1980 at least for the Karnak area near Luxor, the extent of salinization was not documented and its corollaries were not sufficiently elucidated. In this manuscript direct and indirect damage due to salinization of the Karnak Temples complex is identified and illustrated. Recent desalinization efforts are described and future necessary salinization studies are outlined.

The Tomb of Nefertari, no. 66, Valley of the Queens, is an internationally known monument of historic and artistic importance; it is considere d one of the most beautiful of the Royal Egyptian tombs. The fragility of its plaster along with its ubiquitous sodium chloride crystals and microcrystals have complicated its conservation and restoration. In order to determine the optimum pathway for its conservation, the physicochemical processes which occur now in this Tomb must be well understood. To improve this understanding, samples of plaster taken from the Tomb have been analyzed using Differential Scanning Calorimetry and X-ray Diffraction and have been shown to be fully dehydrated; previous findings suggest that this is not the case in all contemporary Royal tombs. Although we are not aware of any kinetic study of gypsum dehydration in the solid state, the presence of anhydrite in the Tomb of Nefertari suggests that the CaSO4 ·2H2O → CaSO4 + 2H2O reaction is catalyzed. It is reasoned that finely-dispersed sodium chloride crystals act as effective catalysts in this reaction.

The protection of glass against water-initiated chemical corrosion is a significant problem. Presently, organic polymers and inorganically modified polymers are being used to protect art glass. However, the service life and durability of these coatings are not entirely satisfactory. Oxide coatings would offer much greater resistance to water penetration. Water permeability through a polymer coating is some ten orders of magnitude larger than that through an oxide coating. This, coupled with a higher scratch resistance, makes oxide coatings promising candidates for the protection of stained glass. Methods to deposit an oxide on glass at relatively low temperatures include sol-gel processing and vapor deposition. This paper compares the performance of different oxide and non-oxide coatings and presents methods for the deposition of oxide coatings at low temperatures.

We describe a new technique for studying thermally-induced chemical transformations in cellulose. The apparatus consists of a carbon dioxide laser for heating, an infrared thermometer, and an optical reflectance spectrometer. To illustrate the technique, we present measurements from a single piece of sample linen along five isotherms in the range 200–290°C. The results are discussed in terms of first-order chemical rate theory and a fourstep model. From the measurements we derive the activation energies, Arrhenius constants, and reflectivities of the chromophoric states.