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 Lithopone B301, Lithopone B311 powder itself may vary in shade over time, ranging from pure white all the way to grey or even black. To suppress this effect, a dopant might be used, like 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.

The produced barium sulfide enters the leacher, and the temperature is controlled above 65°C to obtain a barium sulfide content of 70%, and then enters the clarification barrel, add zinc sulfate for reaction after clarification, control the zinc sulfate content to be greater than 28%, pH=8~9, and obtain a mixture of barium sulfate and zinc sulfide with a density of 1.296~1.357 g/cm3.