Lithopone formula, composition and production explained
Learn what ZnS/BaSO4 means, why lithopone is a composite pigment, and how composition and processing influence industrial use.
What does the lithopone formula mean?
Lithopone is commonly represented as ZnS·BaSO4 or described as a zinc sulfide/barium sulfate composite. This notation identifies the two principal components. It should not be read as proof that every commercial grade is a pure molecular compound with one fixed component ratio.
Zinc sulfide contributes pigmentary light scattering. Barium sulfate contributes to the body and physical behaviour of the composite. Composition, particle characteristics and processing together influence the performance of the finished powder.
The general precipitation reaction
The core reaction is often written as:
BaS + ZnSO4 → ZnS + BaSO4
In the general aqueous process, zinc sulfide and barium sulfate precipitate together. The material then goes through separation, washing and further processing to produce a usable pigment. This is a description of the pigment family, rather than a plant operating recipe or a statement of Longtai’s specific production settings.
Commercial composition can vary with grade and process. Use the agreed product specification when a ZnS content or other limit is important to the purchase.
Why processing and quality control matter
Washing affects residual soluble material. Thermal treatment and subsequent milling influence particle characteristics, dispersion and optical behaviour. Classification and finishing help control coarse material and consistency.
| Quality check | What it helps establish |
|---|---|
| Composition | Whether the offered grade matches the agreed material specification. |
| Whiteness and optical tests | How the material compares under a defined method. |
| Moisture and soluble matter | Information relevant to handling and system compatibility. |
| Sieve residue and dispersion | The presence of coarse material and behaviour in processing. |
A batch inspection report should be matched to the grade and batch identifier on the delivery. Do not compare isolated numerical values without knowing their test method.
Composition does not replace application testing
Lithopone can be evaluated in paints, rubber, plastics and other selected industrial applications. Two powders with similar composition can still perform differently in the same binder because their particle and surface characteristics differ.
Compare Longtai B-301 and B-311 using current data and a representative trial. If the objective is to reduce part of a titanium dioxide package, measure the resulting opacity, colour, stability and total formulation cost.
Handling and storage
Follow the current SDS for the supplied material. Control dust during transfer, keep packaging closed when not in use and protect powder from moisture and contamination. Store away from incompatible chemicals according to the SDS and the site’s handling procedures.
Retain batch information when opening bags or transferring powder into another container so quality records remain traceable.
The separate NIST Chemistry WebBook: zinc sulfide and NIST Chemistry WebBook: barium sulfate records help identify the principal components. They do not define the composition ratio or performance of a supplied commercial grade.
Frequently asked questions
Does lithopone have one fixed molecular weight?
For a commercial composite pigment, composition and grade specification are more useful than assigning one molecular weight to every product.
Is lithopone the same as titanium dioxide?
No. They have different compositions and application behaviour.
How do I request composition details for a grade?
Discuss your application with Longtai Chemical. Include the target grade, required quantity, packaging and destination port so the team can prepare a relevant product recommendation and quotation.
