Museum Conservation Institute

Instrumental neutron activation analysis was used to generate compositional data for nearly 500 Early and Late Classic ceramic and clay samples from ceremonial centers and surrounding hinterland communities in northwest Belize. The purpose of this research was to determine whether diachronic changes exist in the distribution of ceramic wares, and what factors contributed to the modification of exchange systems in this region. The influx of imported material goods into northwest Belize during the Late Classic is attributed to the assimilation of Blue Creek into the expanding trade networks of surrounding communities. The dynamic political landscape in the Central Petén (called the Middle Classic Hiatus) is recognized as a significant contributor to the changes in the exchange of resources in the region, culminating in the increase of market exchange throughout lowland Maya communities.

Ammonium citrate solutions were tested to determine possible damage on marble using two concentrations, four different values of pH and several variations in application. As pH dropped from values of 10 to 7, marble chips immersed in the solutions showed increasing dissolution of calcite, and polished marble tiles to which solutions had been applied showed increasing loss of gloss and brightness. The least damage to marble tiles was produced when solutions were covered during application, and single cleanings were found to be less damaging than multiple cleanings of the same total application time. Comparison with other cleaning agents – ammonium thioglycolate and ethylenediaminetetraacetic acid (EDTA) – showed that ammonium citrate solutions could be as mild as thioglycolate when used in some conditions, such as high pH and low concentration. In contrast, ammonium citrate solutions could harm the stone significantly when used in other conditions, such as pH 7 or high airflow. In these cases, the damage was nearly as much as a 2% solution of EDTA at pH 10. This study emphasizes the need to develop new cleaning products, research which can only go hand in hand with a better understanding of the various interactions taking place between cleaning agent, substrate and environment.

Seventy-five intact Mimbres and Jornada pottery sherds from the American Southwest were analyzed by portable XRF and instrumental neutron activation analysis (INAA). Examination of the data demonstrates that INAA and portable XRF results for elements common to both analyses can be used to construct similar compositional groups. When individual compositional groups are compared to one another, it is apparent that unambiguous separation of compositional groups is challenging by portable XRF given (1) the limited number of key discriminating elements that can be measured relative to INAA, and (2) the relative analytical precision and accuracy of portable XRF for measurements of intact heterogeneous ceramics. We conclude that sourcing intact ceramics by portable XRF is challenging and that bulk analytical measurements, such as INAA, remain a better approach for sourcing archaeological pottery.

Non-invasive Raman microspectroscopy, FTIR, µXRD and XRF were used to identify the materials present in the black, red, and white surface decorations in elected pottery wares from two Prehispanic archae-ological sites in Northwestern (NW) Argentina (AD 900–1530). The iron manganese spinel jacobsite, MnFe2O4, was found to be the main component of two of the fired black decorations analyzed, while hematite and amorphous silicates were found to be present in the red and white fired decorations, respectively. This is the first study, to our knowledge, that firmly identifies jacobsite in black decorations in Prehispanic archaeological ceramics.

In fragments recovered from one site, a carbon-based black pigment was identified while gypsum was observed in the recessed areas of decorative surface incisions. Gypsum, potassium nitrate and halite, most likely deposited during burial, were observed on the surface of some of the fragments analyzed. The results are discussed in the context of the technological processes involved and are compared to compositions previously reported for decorations in ceramic objects from NW Argentina.

A total of 81 pottery and 25 clay samples from the archaeological site and hinterland areas of Blue Creek in northwest Belize were analyzed by instrumental neutron activation analysis and inductively-coupled-plasma mass-spectrometry at the University of Missouri Research Reactor. Data generated for this study offers insight into local clay-resource variability and movement of pottery in the transition from Early (A.D. 250.600) to Late Classic (A.D. 600.850) occupation. Comparison of data generated by the two analytical techniques demonstrates the relative strengths and weaknesses of each method.

The eruption of Parı´cutin (1943–1952), a cinder cone volcano in Michoaca´ n, Mexico, caused dendrochronological and dendrochemical responses that might be useful as general dating tools for eruptions. For the eruption period, pines near Parı´cutin have slightly suppressed ring widths plus high inter-annual variability of width. Wood anatomy changes include traumatic resin ducts and thin bands of false latewood. Dendrochemistry of tree rings shows little temporal variation in most elements, but beginning in 1943 sulfur content increased in rings of four trees and phosphorus content increased in rings of two trees. Hypotheses for increased S and P include new availability of pre-existing soil S and P and/or new input of S and P from the tephra itself. Pines at Parı´cutin also show suppressed ring widths for five years beginning in 1970, and had the eruption date not been known, the most likely conclusion from ring-width data alone would have been an eruption from 1970 to 1974. However, the 1970s suppression was in response to defoliation by a pine sawfly outbreak, not an eruption. For dendrochronological dating of cinder-cone eruptions, a combination of multiple characteristics (width, chemistry, and anatomy) would be more reliable than depending on any one characteristic alone.

Annual growth rings obtained from well dated tree ring cores from Parícutin, Mexico are examined for unique chemical signatures that reflect a known local volcanic eruption and its subsequent atmospheric and terrestrial inputs. Stable carbon isotopic profiles are combined with elemental analyses to construct a chemical profile before, during, and after the known eruptive years (1943-1952) when a cinder cone formed near the town of Parícutin. Data from this well documented eruption are combined with controls obtained from outside the ash fall zone. Carbon isotopes exhibit an enriched spike (~3‰) during the eruptive period followed by a subsequent return to baseline values. This in combination with other stable isotopic indicators and increases in phosphorus, sulfur, and possibly other elements, suggest a unique set of chemical inputs from the eruption. The analytical approach developed here potentially can be used to date unknown eruptions which in the past have often relied on the c...

The ability of inorganic-based analytical chemistry techniques to quantify trace amounts of heavy metals in skeletal remains has been integral for understanding health and social status in human populations. Low detection limits and the sensitivity of inductively coupled plasma- mass spectrometry (ICP-MS) and other techniques to most elements on the periodic table are ideally suited for the quantification of lead (Pb) and other heavy metals in bone. However, the time required for sample preparation and analysis, expense, destructive analytical process, and availability of instrumentation often limit researchers’ ability to utilise these techniques for archaeological applications. This paper explores the use of portable X-ray fluorescence (XRF) instrumentation for heavy metal analysis of bone as an alternative to more traditional analytical techniques. XRF has been shown to be an extremely useful tool for archaeologists seeking to conduct quantitative analyses of cultural materials s...

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RationaleWhole‐bone proteomic analyses rely on lengthy sample preparation including demineralization and digestion to break bone down into peptides to recover using mass spectrometry. However, microwave‐assisted acid hydrolysis, a technique used in proteomic analyses of other soft tissues and cells, will combine both demineralization and digestion and only take minutes.MethodsTo test microwave‐assisted hydrolysis on whole moose bone, we microwaved five concentrations of acetic and formic acids (15%, 12.5%, 10%, 7.5% and 5%) for three times (10, 20 and 30 min) at 140°C using an ETHOS UP high performance microwave digestion system. Peptides were injected and separated using Thermo BioBasic C18 columns and detected with an LTQ Orbitrap Velos mass spectrometer. We searched the raw data on PEAKS 8.5 against the white‐tailed deer database.ResultsFormic acid hydrolysis led to the most complete digestion, and therefore the highest number of peptide spectrum matches, more protein groups and ...

Zinc (carboxylate) soaps, formed by reactions between zinc oxide (ZnO) and fatty acids in a drying oil, are known to cause deterioration in the paint layers of modern and contemporary oil paintings. This study investigates zinc carboxylates that developed in an oil painting test panel designed to mimic the aging and degradation encountered in actual works of art. Following accelerated and natural aging, protrusions were noted on the surface of the test panel. A large protrusion with erupted gel features was extracted from the test panel, mounted in top view, and then cut to reveal the sample's cross section. The gel features, which resulted from the unreacted oil binder's separation from the paint matrix, facilitated zinc carboxylate formation. Using reflectance μ-FTIR and SEM-EDX analysis, the morphologies and spatial distributions of zinc carboxylates within the gel regions of the protrusion were studied. A concentration gradient of zinc within the gel material was observed in the cross-sectional view, indicating patterns of zinc carboxylate formation and migration.

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Zinc white is a commonly used oil paint and ground found in modern and contemporary paintings. Crystalline and amorphous zinc soaps are formed by interactions of zinc oxide pigments and free fatty acids in oil paint and are known to cause paint deterioration in the form of brittleness, efflorescence, delamination, and protrusions. This study aims to gain a better understanding of protrusions from an oil paint test panel using correlative spectroscopies. A test panel was designed to mimic the structure of a layered oil painting using known materials, with a lead white oil ground over which zinc white and cadmium red deep oil paints were layered. As the formation of zinc soaps can take several years, the test panel was accelerated aged [1]. A temperature and humidity benchtop unit from ESPEC was used to cycle between 15 °C and 20% relative humidity (RH) and 50 °C and 80% RH for 10 hours with a 2 hour ramp between set-points for a total of 672 hours. Within another four years of natural aging, metal soap protrusions were observed. Protrusions were sampled, embedded in Bio-Plastic® (synthetic polyester resin), and dry polished. -Fourier transform infrared (FTIR) non-contact mapping in reflectance mode was carried out with a Thermo Nicolet 6700 FTIR spectrometer equipped with a mercury cadmium telluride type A detector, in addition to attenuated total reflection (ATR)-FTIR. Uncoated samples were analyzed in variable pressure mode using a Hitachi S3700-N scanning electron microscope (SEM). Electron dispersive spectroscopy (EDS) was performed using a Bruker XFlash 4010 detector with Esprit software. Samples were analyzed at 15 kV accelerating voltage. X-ray diffraction (XRD) analysis was performed using a Rigaku D/Max Rapid Micro X-ray with Cu Kα radiation at 50 kV, 40 mA and 2 kW.

The chemistry and kinetics of glass alteration have been topics of considerable study and debate over the past several decades. While work is still progressing in understanding the mechanisms by which glass degrades, what has not been as well studied are methods of slowing or preventing the alteration of glass surfaces and objects. This is of significant interest to the heritage science community, where the breakdown of historic glass or glass art objects is proceeding, with few viable options available to museum conservators to mitigate its effects. Experimental measurements using atomic layer deposited (ALD) aluminum oxide coatings on a model silicate glass show a significant reduction of the rate of glass alteration.

Bluish black, highly adherent patches have been observed growing on the Seneca sandstone of the Smithsonian Castle in Washington, DC. They are enriched in Mn compared to the underlying sandstone, by a factor of 100, which suggests that microbial activity plays a role. The mineralogy is likely a mixture of birnessite and todorokite. Estimated thickness is on the order of 250 nm, 3 orders of magnitude thinner than typical desert varnish, and the patches lack the significant clay component found in desert varnish. However, the rate of growth, 9 nm/a, falls within the range of 1-40 nm/a measured for desert varnish. Trace amounts of Mn are found in Seneca sandstone, but they do not appear to be the major contributor to the varnish, which implies that airborne particulate matter would be a significant source. Ambient air concentrations of Mn have been measured at 4 ng/m3 in the District of Columbia.

The London printings of the Chilean postage stamps between 1853 and 1862 were examined using analytical instruments available at the Smithsonian Institution. There are four broad major technical areas important to philatelic research: color science (colorimetry and luminescence), paper chemistry (composition, thickness, and roughness), ink chemistry (pigment and binder composition), and printing methods (engraving and lithography). The analyses performed in this study address these four broad major technical areas while providing an understanding of the characteristics of these stamps, showing the utility and capability of forensic and scientific equipment available to philatelic researchers and offering an effective, rapid, and nondestructive way of identifying the pigments and dyes in the inks and papers used. Xray fluorescence (XRF), Fourier transform infrared spectroscopy (FTIR), colorimetry, and Xray diffraction (XRD) were all used on the stamps without damaging the samples. In...