Papers on Coin Toning

cplradar · Sep 6, 2021

OK - I am getting closer to finding articles on artificial and natural toning. Here is a list of several peer reviewed article just on the process of toning and techiques for analysis

https://www.researchgate.net/profil...ze-Coins-I-Study-on-Archaeological-Patina.pdf

Abstract
This paper presents comparative results concerning the chemical composition and
mineralogical distribution of the main compounds from the structure of the archaeological
patina of ancient bronze coins, which were determined by the corroboration of micro
chemical, IR spectra-photometry, SEM/EDAX and Colorimetric methods. The stratagraphical distribution of the chemical components in the structure of patina is caused by
the pedological processes from the archaeological sites and which represents main
elements used in the authentication of ancient bronze artifacts.
Click to expand...

https://www.sciencedirect.com/science/article/abs/pii/S0169433212003054
XPS and XRF depth patina profiles of ancient silver coins

Abstract
Ancient silver coins of different historical periods going from IV cent. B.C. up to recent XIX century, coming from different Mediterranean countries have been investigated with different surface physical analyses. X-ray photoelectron spectroscopy (XPS) analysis has been performed by using electron emission induced by 1.4 keV X-rays. X-ray fluorescence (XRF) analysis has been devoted by using 30 keV electron beam. Scanning electron microscopy (SEM) has been employed to analyze the surface morphology and the X-ray map distribution by using a 30 keV microbeam.

Techniques were used to investigate about the patina composition and trace elements as a function of the sample depth obtained coupling XPS to 3 keV argon ion sputtering technique.
Click to expand...

https://iopscience.iop.org/article/10.1088/1742-6596/508/1/012032/meta
Analysis of selective laser cleaning of patina on bronze coins

Abstract
The patina, is the result of a large number of chemical, electrochemical and physical processes which occur spontaneously during interaction of metal surfaces with the environment. In this work we want to analyze and remove the patina in artefacts, exposed to atmosphere for various decades. Here, experimental results about the laser cleaning of bronze coins by KrF (248 nm) and Nd:YAG (532 nm) lasers are reported. Both laser wavelengths were efficient to reduce the chlorine concentration on the surface of the coins more than 80 %, as demonstrated by Energy Dispersive X-Ray Fluorescence analyses.
Click to expand...

https://link.springer.com/article/10.1007/s00339-015-9087-2
Nondestructive analysis of Portuguese “dinheiros” using XRF: overcoming patina constraints

“Dinheiros” are the first Portuguese coins, minted with a billon alloy (majority-based copper alloyed with silver). In this work, a set of “dinheiros” from D. Fernando of Portugal was analyzed and the composition of the alloy was compared with other “dinheiros” from previous reigns. Although the coins were in good state of conservation and no active corrosion was macroscopically observable, they still presented a corrosion layer of unknown thickness that would impair the XRF quantitative determinations. In order to overcome this hindrance, the silver K/L intensity ratios were determined and compared for the analyzed samples in order to choose “clean” spots for quantitative analysis. The results show a clear decrease in the Ag content: from 7–9 % in the previous reigns to 0.2–0.3 % in the coins attributed to D. Fernando. The silver content determined is very comparable to the silver content determined in other copper or bronze artifacts analyzed, leading us to believe that this low amount of silver was not intentionally introduced to create a billon alloy but relates to impurities present in the original mineral specimen.
Click to expand...

https://www.sciencedirect.com/science/article/abs/pii/S0026265X18308981

New insights on medieval Provisini silver coins by a combination of non-destructive and micro-invasive techniques

Abstract
The aim of this research was to characterize ten Provisini, one of the most common silver coins in the Middle Age, dating back to the 13th century A.D. These coins are composed by Ag-Cu alloy and were coined in the Roman mint. A non-destructive, micro-destructive and multi-analytical approach was used, aiming to preserve the surfaces of the coins. The results of XRD and micro-Raman spectroscopy allow defining the alloy composition and the mineralogical nature of the alteration products (e.g. cuprite, tenorite, chlorargyrite, stromeyerite). X-ray maps provided information on major elements distribution on the surface. Finally, Electrochemical Impedance Spectroscopy (EIS) and Voltammetry of Immobilized Micro-Particles (VIMP) permitted to reconstruct the possible scheme of the multi-layering of the patina on the coins. Then, the conservation status was monitored.
Click to expand...

http://maajournal.com/Issues/2009/FullTextMondio.pdf
ANCIENT COINS AND THEIR MODERN FAKES: AN
ATTEMPT OF PHYSICO‐CHEMICAL UNMASKING

ABSTRACT
As a consequence of police operations in Messina (Sicily), a huge quantity of perfect
imitations of ancient coins, realized by a sicilian forger, has been recently found. Such
fakes have been realized by the lost wax casting technique and reproduce coins issued
by different authorities in different historical epochs. In order to overcome the obvious
subjectivity of the traditional (autoptical) numismatic analysis, which sometime pro‐
vides contrasting interpretations, five of these fakes have been analysed by Scanning
Electron Microscopy (SEM) and Energy Dispersed X‐Ray Fluorescence (EDXRF). The
results obtained have given information on the microstructure, the homogeneity and the
elemental composition of the alloys used by the forger. Furthermore, evident traces of
the chemical treatment utilized for the artificial ageing of the coins have been found.
Due to the presumable and dangerous large diffusion of these sicilian fakes in the inter‐
national market, the results of such analyses may certainly be of noticeable interest for
Numismatics and forensic applications as well, representing a set of proofs to be used in
the unmasking of analogous counterfeiting cases.
Click to expand...

https://pubs.rsc.org/en/content/articlelanding/2004/ja/b315488b/unauth
LIBS as a diagnostic tool during the laser cleaning of copper based alloys: experimental results†‡

Abstract
In spite of difficulties in quantitative LIBS analysis on copper based alloys, the very low invasiveness of the technique strongly sustains attempts to use it with cultural heritage materials, including ancient bronzes. Analytical results obtained with calibration curves and a calibration free model are compared here on a set of ancient roman coins. An attempt is presented to monitor the laser ablation process on bronze coins and artificially aged standards during the cleaning. The double pulse technique showed that LIBS analytical results could benefit from synchronization between the UV laser sources used, respectively, for cleaning (266 nm) and for LIBS analysis (335 nm).
Click to expand...

https://www.sciencedirect.com/science/article/abs/pii/S0168583X03020135
On the authenticity of eight Reales 1730 Mexican silver coins by X-ray diffraction and by energy dispersion spectroscopy techniques

Abstract
Ancient silver Mexican coins made during the years 1730–1734, were analyzed non-destructively by energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and by optical microscopy. Nine coins of denomination eight Reales were studied. These coins belong to the numismatic private collection in Mexico. Six elements (copper, aluminum, magnesium, silicon, chromium and silver) were determined quantitatively. The coins reveal a uniform Ag concentration. Some of the items are covered with patina. A strong positive correlation between Al and Cu content and also a strong negative correlation between S and Ag were determined. The weight of the coins varied between 26.1344 and 26.9913 g, which is a good indicator of the authenticity of the items. The purpose of this work is to investigate by precise means if some of the coins were falsified or if really all of them are authentic.
Click to expand...

https://www.tandfonline.com/doi/abs/10.1179/174329305X64402
Surface analyses on modern and ancient copper based fakes

Abstract
Over the last two decades, together with the increasing prices in the antique market and the proliferation of private ‘hobby collectors’, the number of fakes in circulation among antique shops, auctions and even institutions and museums has noticeably increased. So called ‘bronzes’ seem to be the favourite objects for both fakers and inexperienced collectors. In some cases the fakes are well made, so that often the professional can be fooled by them also. In this paper some examples of modern and ancient fake objects will be discussed.
Click to expand...

https://analyticalsciencejournals.onlinelibrary.wiley.com/doi/abs/10.1002/jrs.4124
Raman investigation of artificial patinas on recent bronze‒part II: urban rain exposure†

Abstract
Patinas form spontaneously on copper and high copper alloys when exposed to humidity and air. They usually protect the underlying metal from corrosion. Bronze is often chemically patinated by artists to achieve an antique appearance. However, in the case of chemical patinations on bronze, there is a lack of studies about their change over time during exposure to different types of environments.

Recent types of bronze, brown patina and two green type patinas (green chloride and green nitrate patina) applied over a brown patina, were selected for testing. The aim of the present study was to monitor the transformation process of chemically formed patinas and of the bronze itself after exposure to simulated urban acid rain, for a period of 35 days. The structures of the patina and corrosion products were characterized by scanning electron microscopy (SEM) and Raman spectroscopy.

Three differently coloured patinas were scraped off from the bronze statue of the poet France Prešeren, two green type patinas and one brown type, to predict the probable influences of the environment, the base alloy and previously used patination techniques
Click to expand...

https://www.sciencedirect.com/science/article/abs/pii/S0026265X11000919

Corrosion behavior and morphological features of archeological bronze coins from ancient China

Abstract
The archeological round bronze coins, nominated as Wu Zhou and regarded as the first issued effective money in the Han Dynasty of China, have been systematically investigated to disclose their chemical composition, nature of the patina and corrosion features on the coin surface by optical microscopy (OM), X-ray diffraction (X-RD), and scanning electron microscopy (SEM) equipped with backscattered electron (BSE) detector and energy dispersive spectrometry (EDS) techniques. It is revealed morphologically that there are some rough surface cracks, pits, and multicolor patina on the surface of the coins. We prove that the coins are made from bronze material of Cu–Sn–Pb–Sb alloy with contents of 84.8–85.4 wt.% Cu, 3.3–6.1 wt.% Sn, 4.7–6.4 wt.% Pb and 2.6–2.9 wt.% Sb, and covered by two corrosion layers, 25–35 μm for the upper-layer and 20–25 μm for the sub-layer. High chloride content has been detected at the interface between the sub-layer and body of the coins. The lead-rich and tin-rich areas in the coin samples indicate the poor metal compatibility during minting in some locations of the coins. The main compositions of patina are ascertained to be Cu2(OH)3Cl, Cu3(CO3)2(OH)2, Cu2(OH)2CO3, and Pb3O4, and the proposed corrosion mechanism is discussed.
Click to expand...

Log in or Sign up to hide this ad.

cplradar · Sep 6, 2021

https://d1wqtxts1xzle7.cloudfront.n...-lv9XnsYwg__&Key-Pair-Id=APKAJLOHF5GGSLRBV4ZA

cplradar · Sep 6, 2021

https://www.sciencedirect.com/science/article/abs/pii/S0169433212005727

Silver/oxygen depth profile in coins by using laser ablation, mass quadrupole spectrometer and X-rays fluorescence
Author links open overlay panel

Abstract
Silver coins belonging to different historical periods were investigated to determine the Ag/O atomic ratio depth profiles.

Laser ablation has been employed to remove, in high vacuum, the first superficial layers of the coins. Mass quadrupole spectrometry has been used to detect the Ag and the O atomic elements vaporized from the coin surface. The depth profile allowed to determine the thickness of the oxidation layer indicating that, in general, it is high in old coins.

A complementary technique, using scanning electron microscope and the associated XRF microprobe, have been devoted to confirm the measurements of Ag/O atomic ratio measured with the laser-coupled mass spectrometry.

The oxidation layer thicknesses range between about 25 and 250 microns.

Log in or Sign up

Papers on Coin Toning

cplradar Talmud Chuchum

Guest User Guest

cplradar Talmud Chuchum

cplradar Talmud Chuchum

Share This Page

Log in or Sign up

Papers on Coin Toning

cplradar Talmud Chuchum

Guest User Guest

cplradar Talmud Chuchum

cplradar Talmud Chuchum

Share This Page

Useful Searches