Carbonaceous minerals as corrosion products on the surface of bottles

During the corrosion process, as the ion exchange between the surface of the glass and the water progresses, the chemical structure of the surface changes and different structural layers are formed. These layers are characterised by various analytical techniques such as EPMA, XRD, FT-IR, TG-DTA and ICP-OES. Three carbonate mineral species namely calcite (CaCO3), shortite (Na2Ca2(CO3)3) and nyerereite (Na2Ca(CO3)2) have been identified at the outermost deposition layer. Critical parameters that affect the formation of the alkali depleted and silica enriched gel layer are investigated using some special test methods. Methylene blue solution reacts with the silanol groups of gel layer leaving a blue tint behind, the intensity of which varies with the extent of corrosion as the amount of silanol groups outcropped due to the increase of the porous structure area. A colour scale is developed to determine the level of corrosion and the results are correlated with the results of other known chemical analysis methods. The effect of annealing conditions on the chemical resistance of the surfaces and the role of the shape of the bottles on the water condensation at humid atmosphere are studied. The results of acid treatment and re-annealing of the corroded surfaces are described.

Machinability analysis of quartz during single point diamond turning process based on finite element method: influence of ultrasonic vibration and micro-machining parameters

Quartz is one of the difficult-to-machine materials due to its low fracture toughness and high hardness. In this study, the machinability of this material during single point diamond turning (SPDT) was numerically investigated using finite element method (FEM). First of all, the accuracy of the FE model was verified based on the experimental data available in literature. Then, the machinability of quartz was analysed in terms of cutting force, tool/workpiece temperature and tool wear rate. Also, the influence of tool vibration on cutting force and tool wear rate was investigated. Furthermore, an empirical/mathematical model was developed to express the machining outputs as a function of the micro-machining parameters. The obtained results indicate the good performance of FEM in analysing the machinability of quartz during SPDT process.

Selling Whitefriars Stained Glass: James Hogan in the United States 1926–1940

A brief history of stained glass manufacture by James Powell & Sons introduces an account of the firm's success in selling windows in the USA in the interwar years, as recorded in the diaries of James Hogan, their chief designer.

Identification of cord sources in glass using CFD

Cord appearance in the glass industry is a serious problem in high glass quality tableware production. The increased frequency of sharp cords provoked a serious analysis on cord origin and their elimination at the production line. Optical microscopy and electron microprobe analysis (EMA) were applied as direct methods for cord identification. A computational flow dynamics calculation (CFD) and process data analysis were used to verify the hypothesised source of the inhomogeneity. The hypothesis on origin of ZrO2 free cords containing high amounts of Al2O3 was postulated in relation to the refractory material composition of the forehearth. Calculations showed that the suggested mechanism at temperatures between 1200 and 1300°C was relevant. The hypothesis was supported by a change of chemical character of the cords after partial removal of the poorly resistant material. Also the average cord frequency was reduced on a production line from 53 to 17%. CFD simulations indicated that there may exist an effective mixing strategy on cord dissolution. Increasing stirrer rotation speed in a tempering part of the forehearth had a positive effect on cord disruption. The proposed stirrer set up decreased the cord frequency to less than 2%.

Protection of historic stained glass

The process of deterioration of a stained glass window, more precisely of its component glass, lead and paint pigments, has in recent decades been researched thoroughly and is now well understood. The need for the protection in particular of the potash window glasses of the middle ages therefore is widely accepted but not the means of how to achieve this aim. Early attempts such as coatings applied on the glass or the sandwich process, known as Jacobi–Process, have failed for a variety of reasons and with disastrous consequences. Short of removing the windows to safe storage, the only response currently available is the creation of a museum like condition on site in the form of the introduction of an isothermal glazing system. Despite its unquestioned merits, the isothermal glazing system is still in dispute mainly because of its interference with a given historic setting. A variety of designs for the isothermal glazing will be discussed, all aimed at minimising their physical and visual impact on the building, making a strong case in favour of this important protective measure.

Preliminary non-invasive study of Roman glasses from Jesolo (Venice), Italy

Archaeological excavations at ‘Le Mure’ site (Jesolo, VE, Italy) have followed each other since the sixties, when the first evidence of an Early Medieval church (6th–7th century AD) was found under the ruins of a Medieval Cathedral (11th–12th AD). The last few years of investigations by Ca’Foscari University have led to the collection of large amounts of glass fragments, including many tesserae, dating between the 4th and the 12th centuries AD. A selection of glass fragments and mosaic tesserae taken from the excavations performed in 2013–14 at this site were studied by means of reflectance spectroscopy in order to identify their chromophore ions, in particular Cu0, Cu2+, Co2+, Fe2+ and Fe3+, which were detected in both transparent and opaque samples. In addition, the use of high resolution close-up images allowed for the attribution of surface characteristics to specific manufacturing techniques, while glass chemistry was studied in order to group them into known compositional classes. This study, carried out by non-invasive analytical techniques that allowed for the acquisition of preliminary data, will prove useful in driving further methodologies involving other non-invasive and micro-invasive analysis in order to obtain archaeometric information that can be related to concurrent archaeological results.

Advanced technology for in-line continuous heat soak test of tempered sheet glass to guarantee high reliability

Advanced heat soak test (HST) technology, the ‘in-line continuous HST’ has been reported on the basis of experimental investigations and the T-T-T (time–temperature–transformation) relationship. The new HST technology is continuously carried out just after tempering (and heat strengthening) process. It was registered in ISO-20657 (2017). High temperature microscopy observations, high temperature x-ray diffractometry, differential thermal analysis, and micro-Raman spectrometry have been carried out in order to elucidate the α–β phase transformation of nickel sulphide in detail. The breakage ratio of in-line continuous HST is the same as that of conventional off-line HST or excellent. The ‘in-line continuous HST’ is already operating in a Japanese glass plant in order to produce tempered (and heat strengthened) sheet glass with high safety and reliability. The in-line continuous HST technology has the following benefits: (a) improvements of both productivity and reliability, (b) automatic inspection just after the tempering–quenching process, and (c) improvements to productive performance (many kinds products, heteromorphic products, and mass production). In this technical report, the advanced ‘in-line continuous HST’ technology which was standardised by several experimental investigations and analytical results will be shown in detail. The effective and efficient manufacturing technology of the tempered (and heat strengthened) sheet glass will be introduced.