Lithopone (or C.I. Pigment Number 5) is a bright white coloured inorganic compound with the formula BaO5S2Zn2. It usually consists of a mixture of Barium Sulfate and Zinc Sulfide and is generally insoluble in water but is soluble in many organic substances. It is majorly used as a white pigment powder in paints, inks, etc. Due to its lower toxicity and good weathering properties, it was an effective replacement of Lead Carbonate in the late 1800’s.
Lithopone is commonly manufactured by the co-precipitation reaction between Zinc Sulfide and Barium Sulfate. The combinations of both these raw materials are equimolar. The precipitate which forms as a result of this reaction is Lithopone, which is then filtered, calcined at temperatures as high as 600 degrees, and sent for size processing to get its final powdered form.
Paints and Coatings
Lithopone, being brightly white coloured, is widely utilized as a replacement constituent for Titanium Oxide in paint and plasters. It is also combined with Titanium Oxide and used as primers, undercoats, and wall coatings.
It is also used as a major constituent in plasters, putties, mastics, sealing compounds, and adhesives.
Lithopone is used as an algicidal agent and in primers used for curing wood.