What color is BaSO4

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Barium sulfate (BaSO4) is the barium salt of sulfuric acid. In nature, barium sulfate occurs in the mineral baryte (barite), which is used as the main raw material for the production of other barium compounds.

Precipitated barium sulfate is the white filler in many paints and varnishes as barite white, blanc fixe, painter's white and doll's white. It can also be found in opaque white. In the Color Index, barium sulfate, as a synthetic BaSO4 under the name C.I. Pigment White 21 and as "natural" barite under C.I. Pigment White 22 led. It is extremely lightfast and chemically stable. That is why it was given the name Permanent white.

The effect as a white pigment is created by scattering at the interface between the filler and the surrounding binder. Therefore, barium sulfate appears almost transparent in binders which themselves have a refractive index close to that of barium sulfate. This small difference in the refractive indices is advantageous for use as an extender. In systems that are formulated above the critical pigment volume concentration, for example in emulsion paints, additional interfaces between barium sulfate and air are added. The difference in the refractive indices is greater at these, so that the hiding power is significantly increased (dry hiding effect).

When using organic pigments of strong color strength in small quantities, it is customary to produce so-called burns with barium sulfate as the carrier substance. The pigment and barium sulfate are ground together. The color location does not change, but the color strength is significantly reduced. This simplifies the dosing of small amounts of pigment. This method is required for the production of glazes. Even with a nuance of pure white tones, it is advantageous to weigh larger amounts with reduced color strength.

It was first marketed as Blanc fixe in 1830 by Kuhlmann in Lille. Natural ground barite may have been used earlier. However, the barium sulfate produced by precipitation is finer and more brilliant and therefore better suited as a filler.

When mixed with zinc sulfide, it is called Lithopone designated. These arise from mutual failure of BaS and ZnSO4.

Barite is used in the production of fillers in the automotive repair sector.

Barium sulfate is often used as a filler for paper and rubber. A special use is in baryta paper for photo paper.