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.

Lithopone is manufactured by a process (Fig. 1) in which barium sulfide solution is prepared by reducing barite ore (BaSO ₄) with carbon and leaching the resulting mass.

However, the run rates improved after the Chinese government's consistent efforts to reduce electricity rationing in China. The demand forecast remained positive during the quarter, with inquiries coming in from both the local and international markets. As a result of the supply-demand mismatch, the FOB Wuhu debate for TiO2 rutile grade was decided at 3097 USD/MT at the end of the quarter.