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.

4. Refractive index: 1.70~2.25

2. Mentality: the buyer has to prepare goods in advance, and the new order price is slightly less willing to purchase in bulk; Because the seller's inventory is small, the manufacturer has no willingness to reduce the price of sales.Trend: The load of titanium dioxide enterprises is stable, the willingness to ship at low prices is not strong, and the downstream buyers place orders in the early stage to establish inventory, and the short-term supplementary orders after the holiday are less. Anatase titanium dioxide due to the overall volume of the market supply side is less, the space for quotation negotiation is small, and the focus of new orders will move up. It is expected that the titanium dioxide market today just needs to be closed, and the market trading atmosphere is relatively light.

Above 10%, 1 kg of TiO2 should be replaced by 1.3 kg of Lithopone 30%, reducing the amount of polymer accordingly. 

Titanium dioxide is considered safe for use in cosmetics products by expert bodies around the world, including Europe's Scientific Committee on Consumer Safety (SCCS) and the U.S. Food and Drug Administration (FDA). Nano grade titanium dioxide has been assessed by the SCCS and is approved by the European Commission for use as a UV filter.

CSPI says it might reconsider its rating if specifications for food-grade titanium dioxide in the U.S. are updated to ensure nanoparticles are minimized, and new studies are conducted to assess its capacity to cause cancer or other health problems.