titanium oxide colors suppliers

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.

...

One common method to determine sulfate as TiO2 involves gravimetric analysis. In this technique, a sample containing sulfate is treated with barium chloride, resulting in the precipitation of barium sulfate. The precipitate is then filtered, dried, and weighed. The weight of the barium sulfate precipitate correlates directly with the amount of sulfate originally present in the sample. To express this as TiO2, a conversion factor based on stoichiometry is applied. This method, while straightforward, can be time-consuming and subject to errors in filtration and drying.

...