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.
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.