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.

Introduction

In a 2017 study published in Scientific Reports, researchers exposed rats to human-relevant levels of E171 to examine the effects of intestinal inflammation and carcinogenesis. They saw that “a 100-day E171 treatment promoted colon microinflammation and initiated preneoplastic lesions while also fostering the growth of aberrant crypt foci in a chemically induced carcinogenesis model.” They continued: “Stimulation of immune cells isolated from Peyer’s Patches [which are clusters of lymphoid follicles found in the intestine] showed a decrease in Thelper (Th)-1 IFN-γ secretion, while splenic Th1/Th17 inflammatory responses sharply increased,” researchers wrote. “A 100-day titanium dioxide treatment promoted colon microinflammation and initiated preneoplastic lesions.” The scientists concluded: “These data should be considered for risk assessments of the susceptibility to Th17-driven autoimmune diseases and to colorectal cancer in humans exposed to TiO2 from dietary sources.”

Health advocates urge US regulators to ban common food coloring additive, by Tom Perkins, The Guardian, June 2, 2023

When used in food specifically, titanium dioxide is known as an additive called E171 and can be found in products like candy, chocolate, coffee creamer, cake decorations, chewing gum and even vitamin supplements. E171 is often used as coloring additive in foods, to lend the processed item a natural whiteness and opacity — such as in Skittles candy, where it's used as a white base to help give the candies their signature bright, colorful hue.

≤0.3

White powder

In May 2021, the European Food Safety Authority (EFSA) published an opinion that stated that titanium dioxide can no longer be considered safe when used as a food additive.

One of the main challenges that manufacturers face when it comes to buff percentage is ensuring consistency. Variations in the level of coating on titanium dioxide particles can lead to differences in color, opacity, and other properties in the final product. This can be especially problematic in industries such as paint and coatings, where consistency is critical for achieving the desired results.

Titanium dioxide is an insoluble mineral, meaning it cannot dissolve in water. Known for its bright, white pigment, manufacturers use titanium dioxide in many different capacities, including in cosmetics, foods, and drugs. 

When choosing a wholesale supplier for anatase titanium dioxide, it's important to consider factors such as quality, consistency, and reliability. Look for suppliers who have a proven track record of delivering high-quality products on time and in full. It's also a good idea to inquire about the supplier's manufacturing processes and quality control measures to ensure that the titanium dioxide meets industry standards.