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Glass surface cleaning is the very first step in advanced coating deposition and it also finds use in conserving museum objects. However, most of the wet chemical methods of glass cleaning use toxic and corrosive chemicals like concentrated sulfuric acid (HSO), piranha (a mixture of concentrated sulfuric acid and 30% hydrogen peroxide), and hydrogen fluoride (HF). On the other hand, most of the dry cleaning techniques like UV-ozone, plasma, and laser treatment require costly instruments. In this report, five eco-friendly wet chemical methods of glass cleaning were evaluated in terms of contact angle (measured by optical tensiometer), nano-scale surface roughness (measured by atomic force microscopy or AFM), and elemental composition (measured by energy dispersive x-ray spectroscopy or SEM-EDX). These glass cleaning methods are devoid of harsh chemicals and costly equipment, hence can be applied in situ in close proximity with plantation such as greenhouse or upon subtle objects such as museum artifacts. Out of these five methods, three methods are based on the chemical principle of chelation. It was found that the citric acid cleaning method gave the greatest change in contact angle within the hydrophilic regime (14.25° for new glass) indicating effective cleansing and the least surface roughness (0.178 nm for new glass) indicating no corrosive effect. One of the glass sample showed unique features which were traced backed to the history of the glass usage. [ABSTRACT FROM AUTHOR]

This article reviews the principles, mechanisms and comparisons of glass surface cleaning by various wet chemical and dry cleaning methods, including acid-base-solvent combinations, HF etching, chelation, vapor degreasing, UV-ozone, oxygen plasma, heating/pyrolysis, ultrasonic and laser treatments. This article also covers four major hydrophobic coating strategies, namely hydrosilylation, silanization, plasma treatment and DC sputtering, along with their process-wise applications. A special emphasis is given on the silanization process: its mechanism, factors affecting, choices of solvents and precursors, and limitations, which is utilized in anti-reflective (AR) sol-gel coating formation as well. Some of the common surface analytical techniques, its utility and reported data has also been reviewed in this context. Finally, a section has been devoted to anti-reflective (AR) and transmittance properties, elucidating the theory and methods of AR coating generation, factors affecting and related literature reports. The challenge lies in coming up with non-harsh cleaning procedures and water-based hydrophobic coatings, with an eye for application in ecological proximity. Graphical Abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]