Commonly known as Barytes, it's non-toxic, chemically and physically unreactive. Barytes is used as a functional filler, extender and weighting agent in paint, rubber, radiation shielding and friction lining applications.
About 80% of the world's barium sulphate production, mostly purified mineral, is consumed as a component of oil-well drilling fluid. It increases the density of the fluid, increasing the hydrostatic pressure in the well and reducing the chance of a blowout.
Barium Sulphate in suspension is frequently used medically as a radiocontrast agent for X-ray imaging and other diagnostic procedures. It is most often used in imaging of the GI tract during what is colloquially known as a "barium meal". It is administered orally, or by enema, as a suspension of fine particles in a thick milk like solution (often with sweetening and flavouring agents added). Although barium is a heavy metal, and its water-soluble compounds are often highly toxic, the low solubility of barium Sulphate protects the patient from absorbing harmful amounts of the metal. Barium Sulphate is also readily removed from the body, unlike Thorotrast, which it replaced. Due to the relatively high atomic number (Z = 56) of barium, its compounds absorb X-rays more strongly than compounds derived from lighter nuclei.
The majority of synthetic barium Sulphate is used as a component of white pigment for paints. In oil paint, barium Sulphate is almost transparent, and is used as a filler or to modify consistency. One major manufacturer of artists' oil paint sells "permanent white" that contains a mixture of titanium white pigment (TiO2) and barium Sulphate. The combination of barium Sulphate and zinc sulphide (ZnS) is the inorganic pigment called lithopone. In photography it is used as a coating for certain photographic papers.
A thin layer of barium Sulphate called baryta is first coated on the base surface of most photographic paper to increase the reflectiveness of the image, with the first such paper introduced in 1884 in Germany. The light-sensitive silver halide emulsion is then coated over the baryta layer. The baryta coating limits the penetration of the emulsion into the fibers of the paper and makes the emulsion more even, resulting in more uniform blacks. (Further coatings may then be present for fixing and protection of the image.) More recently, baryta has been used to brighten papers intended for ink-jet printing.
Barium Sulphate is commonly used as a filler for plastics to increase the density of the polymer in vibrational mass damping applications. In polypropylene and polystyrene plastics, it is used as a filler in proportions up to 70%. It has an effect of increasing acid and alkali resistance and opacity.
As barium Sulphate has high burning point and is insoluble in water, it is used as a coating material in casting of copper anode plates. The anode plates are cast in copper moulds, so to avoid the contact of the liquid copper and the solid copper mould, a solution of barium Sulphate in water is used as a coating material on the mould surface. Thus when the liquid copper solidifies in form of an anode plate it can be easily released from its mould.