microfine titanium dioxide factories

This article discusses the discovery of phosphorescent lithopone on watercolor drawings by American artist John La Farge dated between 1890 and 1905 and the history of lithopone in the pigment industry in the late 19th and early 20th centuries. Despite having many desirable qualities for use in white watercolor or oil paints, the development of lithopone as an artists' pigment was hampered by its tendency to darken in sunlight. Its availability to, and adoption by, artists remain unclear, as colormen's trade catalogs were generally not explicit in describing white pigments as containing lithopone. Further, lithopone may be mistaken for lead white during visual examination and its short-lived phosphorescence can be easily missed by the uninformed observer. Phosphorescent lithopone has been documented on only one other work-to-date: a watercolor by Van Gogh. In addition to the history of lithopone's manufacture, the article details the mechanism for its phosphorescence and its identification aided by Raman spectroscopy and spectrofluorimetry.

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The production process of titanium dioxide involves several stages, starting with the extraction of raw materials from mineral ores such as ilmenite, rutile, and anatase. These ores are then processed through various methods, including the sulfate and chloride processes, to produce high-purity titanium dioxide powder. The sulfate process involves treating the ore with sulfuric acid to extract titanium dioxide, while the chloride process uses chlorine gas to produce a purer form of the pigment.

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