ironing board cover 135 x 55_the tablecloth factory

Although barium sulfate is almost completely inert, zinc sulfide degrades upon exposure to UV light, leading to darkening of the pigment. The severity of this UV reaction is dependent on a combination of two factors; how much zinc sulfide makes up the pigments formulation, and its total accumulated UV exposure. Depending on these factors the pigment itself can vary in shade over time, ranging from pure white all the way to grey or even black. To suppress this effect, a dopant may be used, such as a small amount of cobalt salts, which would be added to the formulation. This process creates cobalt-doped zinc sulfide. The cobalt salts help to stabilize zinc sulfide so it will not have as severe a reaction to UV exposure.

Rebecca Capua is an assistant conservator in the Paper Conservation Department at the Metropolitan Museum of Art since 2009. She received an MA in art history and an Advanced Certificate in art conservation from the Conservation Center, Institute of Fine Arts, New York University in 2007. Her primary area of research is on the materials of American artists of the late 19th and early 20th century. Address: The Sherman Fairchild Center for the Conservation of Works on Paper, Metropolitan Museum of Art, 1000 Fifth Avenue, New York, NY 10028. Email: rebecca.capua@metmuseum.org.

The global Lithopone market is highly consolidated and a major bulk of Lithopone is produced in China. Some of the major Lithopone producers include Anhui Union Titanium Enterprise Co. Ltd., Fengchen Group Co. Ltd., Henan Premtec Enterprise Corporation, Langfang Pairs Horses Chemical Co. Ltd., Natural Pigments Inc., Noah Technologies Corporation, Titanos Group, VB Technochemicals SA, Venator Materials PLC, and ZhengZhou Sino Chemical Products Co. Ltd.