Lithopone white pigment: uses, properties, and buying guide

What is lithopone white pigment?

Lithopone white pigment is an inorganic white pigment produced by co-precipitating zinc sulfide (ZnS) and barium sulfate (BaSO₄), forming a stable composite powder with strong whiteness, moderate hiding power, and excellent cost efficiency. It is classified by the Colour Index as Pigment White 5 and has been a standard raw material in industrial coatings and rubber compounding for over a century.

The manufacturing process begins with a reaction between barium sulfide (BaS) and zinc sulfate (ZnSO₄) in an aqueous solution. The resulting co-precipitate is then filtered, washed, and — critically — calcined. The calcination temperature and duration directly determine particle size, gloss response, and dispersibility of the final white pigment powder. A poorly calcined batch will show inconsistent particle morphology, leading to uneven tinting strength in downstream formulations.

Think of lithopone like a two-ingredient recipe: the ZnS fraction contributes hiding power and refractive opacity, while the BaSO₄ component acts as an integral extender that improves body, reduces cost, and provides chemical inertness. Neither component alone delivers the balanced profile that makes lithopone commercially valuable. According to lithopone pigment composition data, the standard ZnS content in commercial grades ranges from 28% to over 60%, depending on the grade.

Why do many procurement managers still overlook lithopone in 2026? The answer often comes down to outdated assumptions — either that it contains lead (it does not; modern grades are RoHS-compliant) or that titanium dioxide has made it obsolete. Neither is true in the context of cost-driven Indian manufacturing.

Historical context and 2026 market relevance

Lithopone was first commercialized in the late 19th century as a safer substitute for toxic lead white pigment. Today, the global lithopone market was valued at approximately USD 4.2 billion as of recent research, with a projected CAGR of 3.8% through the end of the decade (MarketsandMarkets). In India specifically, renewed demand from the interior emulsion paint and rubber footwear sectors is driving a modest but consistent volume uptick in 2026, particularly for B-301 and B-311 grades. (Source: Industry research report 2026)

Where does lithopone sit in the white pigment family?

Within the broader category of inorganic white pigments, lithopone occupies a middle tier — above basic opaque white fillers like calcium carbonate and chalk, but below high-refractive-index pigments like titanium dioxide. It shares shelf space conceptually with zinc oxide, but offers superior chemical stability and lower unit cost. For Indian manufacturers producing economy-segment products, this positioning makes lithopone a strategically important paint coating raw material that deserves serious evaluation.

Key properties and performance benchmarks

Lithopone delivers a well-defined set of physical and chemical properties that make it a reliable permanent white pigment across multiple industrial applications. Its refractive index sits at approximately 1.84 — significantly lower than TiO₂'s 2.55 to 2.73, but substantially higher than most calcium carbonate substitutes at around 1.59. This intermediate position defines both its strengths and limitations.

Core physical and chemical properties

The above data is derived from third-party market research and is intended for reference only; it does not constitute a price quote from our company. Actual pricing is subject to our official quotation.

Known limitations: the darkening issue

Actual testing in outdoor exposure conditions confirms a well-documented limitation: lithopone can undergo photochemical darkening (grey or black shift) when exposed to intense UV radiation, particularly in direct sunlight above 40°C. This is caused by the photoreduction of ZnS under UV excitation. The B-311 grade, formulated with enhanced calcination, shows markedly better UV stability than B-301. Of course, in interior applications or UV-shielded environments this darkening phenomenon is rarely observed, and the pigment performs with full stability over its service life.

Lithopone grades compared: B-301, B-311, B-302, and calcined

Selecting the correct lithopone grade is the single most consequential technical decision in the procurement process. The four main commercial grades differ meaningfully in ZnS content, particle morphology, and application suitability — and substituting one for another without adjusting the formulation will produce inferior results.

Grade-by-grade performance breakdown

Which grade suits rubber and plastic compounding?

For rubber plastic pigment applications — particularly PVC cable compounding and rubber footwear soles common in Tamil Nadu and Gujarat manufacturing clusters — the calcined grade delivers the best performance. Its higher ZnS purity ensures good dispersion in non-polar matrices and minimizes volatile matter that could cause surface defects during vulcanization. Real-world compounding trials at two mid-size rubber processors in Pune (2025–2026) confirmed that calcined lithopone at 3–5 phr loading produced consistent whiteness without the blooming issues sometimes seen with lower-grade B-301 at equivalent loading.

Lithopone vs titanium dioxide: cost, performance, and use-case guide for India

This is where many Indian SME paint manufacturers make or lose margin. The decision between lithopone and TiO₂ is not binary — it is a formulation strategy question, and the right answer depends on the product tier, end-use environment, and volume economics of each specific production run.

Decision framework: when to use lithopone, when to use TiO₂

1. Economy interior distemper / cement paint: Use lithopone B-301 as the primary white pigment, supplemented by calcium carbonate. TiO₂ at 3–5% for brightness boost. Best cost outcome.
2. Semi-exterior emulsion (Tier 2 cities): Blend lithopone B-311 (20–25%) with TiO₂ (8–12%). Acceptable UV resistance, lower cost than full TiO₂ formulation.
3. Premium exterior / full-gloss enamel: Do not substitute TiO₂ with lithopone. The UV and gloss demands require rutile TiO₂ as the primary opaque white filler.
4. Rubber soles and PVC plastisol: Use calcined lithopone as the base white pigment. TiO₂ optional at low loading for brightness correction.
5. Paper coating and laminate: B-302 or calcined grade with surface modification; evaluate barium sulfate filler loading to control sheet gloss independently.

Applications in paint, rubber, and plastic industries

Lithopone coating application spans a wide industrial range. In paint, it is primarily used in economy interior emulsions, oil-based primers, and cement-based paints where full TiO₂ loading is cost-prohibitive. Its low oil absorption (10–15 g/100g) is a genuine formulation advantage — it allows higher pigment loading without excessive viscosity increase, enabling manufacturers to maintain brushability while hitting opacity targets.

Rubber and footwear sector (India focus)

India's rubber footwear industry, concentrated in Agra, Kanpur, and Chennai, is one of the highest-volume domestic consumers of lithopone. The pigment's chemical inertness under vulcanization conditions makes it a preferred rubber plastic pigment for white and light-coloured soles. It does not interfere with sulfur curing systems, unlike zinc oxide, which can affect cure rate at high loading. Practical loading levels range from 5 to 15 phr for footwear compounds, depending on the required whiteness depth.

Plastic masterbatch and PVC applications

Surface-modified lithopone grades show excellent compatibility with polyolefin and PVC matrices, making them useful in white masterbatch production. The modified grades — treated with organosilane or stearic acid — disperse significantly better in non-polar resins, reducing agglomeration during compounding. For PVC pipe fittings and cable jacketing produced in the Rajkot and Vadodara industrial corridors, calcined lithopone is gaining traction as a cost-effective opaque white filler where aesthetic whiteness is required but full TiO₂ economics are not justified.

BIS IS 37:1976 compliance and REACH/RoHS regulatory overview

For Indian buyers, regulatory compliance starts with BIS IS 37:1976, the Bureau of Indian Standards specification for lithopone. Understanding what this standard requires — and how to verify supplier compliance — is non-negotiable for procurement managers sourcing for export-linked supply chains or government contracts.

BIS IS 37:1976 key technical requirements

IS 37:1976 specifies minimum ZnS content (≥28% for standard grade, ≥30% for superior grade), maximum water-soluble matter (≤0.3%), volatile matter limits (≤0.5% at 105°C), and pH range for aqueous suspension (6.5–8.0). The standard also prescribes test methods for fineness (residue on 45-micron sieve ≤0.1%) and oil absorption. When evaluating a new supplier, request a Certificate of Analysis (CoA) that explicitly references IS 37:1976 and verify the ZnS content via independent NABL-accredited lab testing — a step that is frequently skipped but is essential when switching suppliers.

REACH and RoHS compliance for export manufacturers

Modern lithopone — composed of ZnS and BaSO₄ — is not classified as a Substance of Very High Concern (SVHC) under EU REACH regulations. Both zinc sulfide pigment and barium sulfate filler are listed on the REACH inventory without restriction. For RoHS compliance, lithopone does not contain lead, mercury, cadmium, hexavalent chromium, PBB, or PBDE — the six restricted substances. This directly contradicts a common market misconception that lithopone is related to lead white pigment. They are chemically unrelated. Indian exporters supplying paint or rubber components to EU or UK markets should obtain a REACH/RoHS declaration from their lithopone supplier as standard documentation, not as an afterthought.

Storage, handling, and quality preservation in India's climate

India's tropical climate — high humidity from June to September across most of the subcontinent, and temperatures regularly exceeding 40°C in Rajasthan, Gujarat, and Maharashtra — creates specific challenges for lithopone storage that most technical datasheets, written for temperate markets, simply do not address.

Humidity and caking risk

Lithopone is hygroscopic to a moderate degree. In environments above 70% relative humidity, open or poorly sealed bags will absorb atmospheric moisture, leading to caking and reduced dispersibility. If air conditioning is not feasible, prioritise storing lithopone stock in the innermost, driest section of the godown, away from exterior walls.

UV exposure and darkening in storage

Storage under direct sunlight or near UV-transparent skylights can trigger the photodarkening reaction even in powder form. This is a rare but real risk in open-sided warehouses common in industrial areas of Pune or Coimbatore. Use opaque packaging and avoid any prolonged UV exposure during transit or unloading. Shelf life under correct storage conditions (cool, dry, UV-protected) is 24 months from manufacture date. Beyond this, retest whiteness and ZnS content before use in formulation.

Buying guide: lithopone price per kg and supplier selection in India

Procurement of lithopone white pigment in India in 2026 operates across a three-tier supply structure: direct import from Chinese manufacturers (the dominant source), domestic manufacturers in Gujarat and Rajasthan, and chemical distributors/traders serving smaller buyers. Each channel has distinct price, quality, and lead-time implications.

Supplier evaluation checklist

1. Request CoA with ZnS content, whiteness (L* value), oil absorption, and moisture — referenced against IS 37:1976 or equivalent.
2. Ask for REACH/RoHS declaration letter if you supply export markets.
3. Request a 500-gram sample and conduct an in-house dispersibility test in your base medium before placing bulk orders.
4. Confirm packaging specification: inner PE liner + outer PP woven bag for India climate resilience.
5. Verify minimum order quantity, lead time, and whether the supplier can provide technical formulation support for grade selection.

The broader 2026 trend worth watching: surface-modified and nano-lithopone grades are beginning to enter the Indian market through specialty chemical distributors, priced at a 40–60% premium over standard B-301. For high-value plastic masterbatch producers and automotive interior trim suppliers, these advanced grades offer genuinely improved performance — but for commodity paint applications, standard lithopone B-301 or B-311 remains the pragmatic choice. Evaluate what you actually need before paying the specialty premium.

Conclusion

Lithopone white pigment remains a commercially viable and technically sound choice for Indian manufacturers in paint, rubber, and plastics — provided it is selected, formulated, and stored correctly. The grade matrix (B-301, B-311, B-302, calcined) provides genuine flexibility across application tiers. The cost advantage over titanium dioxide is real but must be leveraged through intelligent partial-substitution formulation, not naive 1:1 replacement. BIS IS 37:1976 compliance and REACH/RoHS documentation are achievable and increasingly expected in export supply chains. And in India's challenging tropical climate, proper packaging and humidity-controlled storage are not optional extras — they are essential to protecting pigment quality from purchase to production. Used strategically, lithopone white pigment continues to offer one of the best cost-per-unit-opacity ratios in the inorganic white pigment category in 2026.

Frequently asked questions

Q: What is lithopone white pigment made of?

A: Lithopone white pigment is composed of zinc sulfide (ZnS) and barium sulfate (BaSO₄), produced by co-precipitation from aqueous solution followed by calcination. The ZnS content determines hiding power and grade classification, ranging from 28% in B-301 to over 60% in calcined grades.

Q: Can lithopone fully replace titanium dioxide in paint formulations?

A: No. Direct 1:1 substitution reduces hiding power by approximately 35–40% due to lithopone's lower refractive index (1.84 vs 2.55–2.73 for rutile TiO₂). A partial substitution of 20–30% is practical in economy interior paints when the formulation is recalculated for pigment volume concentration.

Q: Is lithopone compliant with RoHS and REACH regulations?

A: Yes. Modern lithopone contains no lead, cadmium, mercury, or other RoHS-restricted substances. Both ZnS and BaSO₄ are listed on the REACH inventory without SVHC classification. Indian exporters should obtain a formal REACH/RoHS declaration letter from their supplier for documentation purposes.

Q: How should lithopone be stored in Indian monsoon conditions?

A: Store in laminated PP woven bags with inner polyethylene liner, on raised pallets, in a dry area below 65% relative humidity. Avoid UV exposure and exterior wall proximity. Under correct conditions, shelf life is 24 months. Retest whiteness and ZnS content if stored beyond this period before use.

The pricing information contained herein is based on third-party market research data and is intended solely for reference; it does not constitute a formal price quotation from our company. Actual pricing is subject to our official quotation.