uses lithopone quotes

Having thus described the origin and uses of the pigment, we now come to the question, what is lithopone? It is, in short, a chemical compound usually consisting of 30.5 per cent zinc sulphide, 1.5 per cent zinc oxide and 68 per cent barium sulphate, but these proportions vary slightly in the different makes. Lithopone of this composition is sold as the highest grade, either as red seal or green seal, as it best suits the idea of the manufacturer. Many manufacturers, especially in Europe, sell and also export other brands under other seals, containing 24, 20, 18 and as little as 12 per cent of zinc sulphide with very small percentages of zinc oxide, the balance being usually barium sulphate, but sometimes certain portions of China clay or gypsum (calcium sulphate) or whiting (calcium carbonate). Such brands are not a chemical compound, but mechanical mixtures of the chemically compounded lithopone and the admixtures referred to.

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uses lithopone quotes2025-08-15 18:41
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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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uses lithopone quotes2025-08-15 17:27
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The raw material used in this method is FeSO4. In order to maintain the Fe3 + concentration in the reaction medium in a specific range, reducing agent iron sheet is added in the reaction process. Iron yellow crystal seed was added and air was introduced to synthesize iron yellow under certain pH conditions. The method mainly includes two steps: (1) firstly, FeSO4 · 7H2O is used as raw material, NaOH or NH3 · H2O is used as precipitant or pH regulator, and air is used as oxidant to prepare crystal seed; (2) Iron yellow is produced by two-step oxidation with crystal seed, FeSO4, iron sheet and air.

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uses lithopone quotes2025-08-15 17:04
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