Lithopone

Mixture of inorganic compounds, widely used as a white pigment powder

View Details

Chemical compound

Lithopone, C.I. Pigment White 5, is a mixture of inorganic compounds, widely used as a white pigment powder. It is composed of a mixture of barium sulfate and zinc sulfide. These insoluble compounds blend well with organic compounds and confer opacity. It was made popular by the cheap production costs, greater coverage. Related white pigments include titanium dioxide, zinc oxide ("zinc white"), zinc sulfide, and white lead.[1]

History

Lithopone was discovered in the s by DuPont. It was manufactured by Krebs Pigments and Chemical Company and other companies.[2] The material came in different "seals", which varied in the content of zinc sulfide. Gold seal and Bronze seals contain 40-50% zinc sulfide, offering more hiding power and strength.[3] Although its popularity peaked around , approximately 223,352 tons were produced in . It is mainly used in paints, putty, and in plastics.[1]

Stability and darkening

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.

Production

Lithopone is produced by coprecipitation of barium sulfate and zinc sulfide. Most commonly coprecipitation is effected by combining equimolar amounts of zinc sulfate and barium sulfide:

BaS + ZnSO4&#; ZnS · BaSO4

This route affords a product that is 29.4 wt % ZnS and 70.6 wt % BaSO4. Variations exist, for example, more ZnS-rich materials are produced when zinc chloride is added to the mixture of zinc sulfate and barium sulfide.[1]

Barium sulfide is produced by carbothermic reduction of barium sulfate. Zinc sulfate is obtained from a variety of zinc products, often waste, by treatment with sulfuric acid.

Safety

Lithopone is rather nontoxic, due to the insolubility of its components. It has been used in medicine as a radiocontrast agent. Lithopone is allowed to be in contact with foodstuffs in the US and Europe.[1]

See also

References

Historical references

Description

Colour:  Lithopone White pigment &#; Blanc Lithopone

Details: Dry Ground Pigment Powder

Technical characteristics :
Chemical name : zinc sulfide and barium sulphate
Color index : W5
Case no : -05-7
Apparent density : 823 g/l
UV resistance : good
Coloring power : good

Use : lime, wax, paint, plaster, fresco, glaze, cement, fine arts.
Lithopone White pigment is in powder. For use in artistic paint, it should be finely ground in a mortar before mixing it with the binder.

Linseed oil : dilute the powder in some turpentine oil before adding it to linseed oil.
Paint with water/lime paste : dilute the pigment in some water to make it liquid before incorporating it into the paint.
Lime powder/cement/plaster : directly incorporate the pigment (up to 10% based on the weight of the binder), then mix in order to stain all of your binder.

Maximum dosage : The maximum dosage is 10% compared to the binder used.  Above 10% it is recommended to incorporate fixators and adjuvant (lime use).

Lithopone White pigment is 100% synthetic.

Made in France.
History :  Also called &#;white of Comines&#;, this pigment is used for paintings since the Antiquity.

Sign up to our mailing list

Full Name

Address

*

The company is the world’s best lithopone powder supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.