Rublev Colours Lithopone is an organically coated white pigment based on a co&#;precipitated zinc sulfide/barium sulfate compound. The zinc sulfide content is 30% by weight, whereas, on a molecular basis, lithopone consists of the two components at a ratio of 1:1. It is a transparent white almost equal to zinc oxide in whiteness. It holds a medium position in density between lead white and zinc white.
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Pigment Names
Primary NamesEnglish: lithoponeThe inception and evolution of lithopone can be traced back through various industries and diverse applications. Revered for its robust hiding power, this white pigment, also called sulfide of zinc white, has been an invaluable asset to industries requiring a durable and reliable white pigment. Lithopone was an economical and functional solution as an alternative to lead carbonate, which is prone to change, and zinc oxide, known for its brittleness.
Historically, the first mentions of zinc sulfide being utilized as a pigment were approximately sixty years before the everyday use of lithopone. Originally, it was thought to be appropriate for coloring rubber. In England, a patent was granted for this process. Two decades after this, the focus shifted to zinc sulfide as a suitable pigment for paint. The year witnessed the patenting of a manufacturing process for a novel white pigment composed of zinc sulfide and barium sulfate. Dubbed Charlton white or Orr&#;s white enamel, this began a new era for white pigments.
The composition of lithopone underscores its superiority in specific applications. Ideally, prepared lithopone consists of 30 to 32 percent sulfide of zinc, and a negligible percentage of zinc oxide (1.5%), with the remaining majority being barium sulfate. These attributes render lithopone nearly comparable to the best grades of French process zinc oxide in terms of whiteness. Furthermore, its oil absorption, which sits between lead carbonate and zinc oxide, solidifies its position as a functional and efficient white pigment.
In terms of application, meticulous preparation and attention to detail yield the best results. For paint grinders, maintaining a ratio of 12 pounds of refined linseed oil to 88 pounds of lithopone pigment will provide optimal workability. A salient factor that should be heeded is the state of the lithopone before mixing with oil; the material must be sufficiently dry. Only then will it integrate seamlessly with the oil, ensuring that the resultant mixture possesses the desired consistency and properties.
Lithopone&#;s historical significance is further accentuated by the advancements and modifications that followed its inception. The patent by J.B. Orr, for instance, ushered in a new white pigment&#;Orr&#;s Zinc White. This innovation was attained by co-precipitating zinc sulfate and barium sulfide, followed by a calcination process. Further refinements marked the subsequent decades, the most notable being the enhancement of lightfastness achieved in the s by introducing small amounts of cobalt salts before calcination.
While lithopone and anatase titanium white gained traction between the s and s, by the advent of the First World War, rutile titanium white had started to overshadow them. Their significance in the artist&#;s palette has since dwindled, and their use as an artist&#;s pigment is currently nearly obsolete.
From a stability standpoint, lithopone, a fusion of zinc sulfide and artificially precipitated barite, is non-toxic and exhibits resilience to mild lyes and acids. However, it is incompatible with colors containing copper. Despite its strong covering power in oil, lithopone&#;s drying capabilities are notably limited, posing potential issues for artists. Notably, early experimentation with lithopone-based grounds instead of zinc white resulted in undesirable darkening, although this blackness receded upon drying. This unpredictable behavior has sparked debate among scientific communities, emphasizing the need for further exploration and understanding of this pigment.
With its storied history and distinct properties, lithopone remains a subject of historical significance and contemporary relevance. While its applications and popularity have evolved, its role in the annals of pigment history is indisputable.
Lithopone
Pigment:LithoponePigment Classification:Synthetic inorganicColour Index:Pigment White 5 ()Chemical Name:Barium sulfate/zinc sulfideChemical Formula:BaSO4&#;ZnSCAS No.-05-7EINECS No.215-715-5ASTM LightfastnessAcrylic:Not ListedOil:Not ListedWatercolor:Not ListedPhysical Properties
Zinc Sulfide (ZnS): Approx. 30%Barium Sulfate (BaSO4): Approx. 70%Colorimetric Index L*:97Sieve Residue, >45 μm:< 0.004%pH:8Hardness (Mohs):3Density:Approx. 4.36 g/mlMolar Mass:330.80 g/molSpecific Gravity:4.3Bulking Value:35.82 lbs/gal
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Lithopone was developed in the s as a substitute for lead carbonate (lead white), to overcome its drawbacks of toxicity and poor weathering resistance. Within a few years, titanium dioxide displaced lithopone to become the white pigment (PW6) par excellence in the industry and the world&#;s best-selling inorganic pigment. However, titanium is a product whose price is subject to large price variations due to product availability. These price increases affect the competitiveness of finished products, and so the search for an alternative to titanium dioxide has generated a variety of possibilities to optimise its use.
Lithopone, an
alternative to titanium dioxide
Lithopone is a white pigment (PW5) co-precipitated from solutions of zinc and barium salts according to the following reaction:
ZnSO4 &#; BaS &#; BaSO4*ZnS
Thanks to its rheological and optical properties, Lithopone 30% offers both technical and economic advantages in the substitution of titanium dioxide in different applications. Among these advantages, it has been observed that Lithopone 30% has algaecidal properties in paints, which gives greater protection to the coating.
Studies have been carried out with both emulsion paints and powder paints, both with clear results on how the use of Lithopone 30% reduces the appearance of algae in the paint once it has been applied (see photos).
Lithopone 30% complies with both the REACH and Indirect Food Regulations, as well as with many European regulations regarding Toys, Packaging, Resins, etc&#;
The applications in which it can be used are paints, inks, plastics, elastomers, paper, fillers, adhesives&#;
Partial substitution of titanium dioxide in liquid paints
Lithopone 30% has a lower coverage power than titanium dioxide. For this reason, Lithopone 30% can only partially substitute titanium dioxide, between 5 and 40%.
Below 20% substitution, it is recommended to replace 1 kg of TiO2 with 1 kg of Lithopone.
Above 20%, it is recommended to replace 1 kg TiO2 with 1.3 kg of Lithopone 30%.
In order to achieve the same solids content, the larger filler and the binder should be reduced if necessary.
By doing so, we achieve cost reduction, increased film strength and improved fungicidal and algaecidal properties.
Example of partial substitution of titanium dioxide with Lithopone 30% in a liquid paint.
ComponentBase Paint10% TiO220% TiO240% TiO2
Pairs Horses Chemical Product Page
Ref 1:1Ref 1:1Ref 1:1WaterThickener (Celluoseether)Dispersing Agent, AcrylicLithoponeTiOCaCOBinderAdditives (Biocide, pH Corr., Antifoam, etc.)
Lithopone in plastics and masterbatch
Lithopone 30% increases extruder performance and reduces processing costs, improves quality and is suitable for masterbatch for injection of Polyolefins, ABS, Polycarbonate, Polypropylene, Polyethylene, Polystyrene, single layer films, multi-layer films and for white, coloured and filled masterbatch. The combination of Lithopone 30 with TiO2 results in improved mechanical properties including higher elongation values and better impact resistance.
Lithopone 30% applied in masterbatch has maximum purity, good opacity and reasonable light fastness.
Below 10% substitution, 1 kg of TiO2 should be replaced by 1 kg of Lithopone 30%.
Above 10%, 1 kg of TiO2 should be replaced by 1.3 kg of Lithopone 30%, reducing the amount of polymer accordingly.
Example of partial substitution of titanium dioxide with Lithopone 30% in a white
masterbatch
Lithopone in natural and synthetic elastomers
Lithopone 30% is a perfect alternative to titanium dioxide in all natural and synthetic pigmented elastomers, as it is non-abrasive and extremely acid resistant.
Lithopone 30%, in any type of rubber, not only reduces the cost of partial substitution of TiO2 but also increases industrial production and improves the durability and the thermal and mechanical resistance of the finished product.
Lithopone in fillers, adhesives, joints and sealants
Lithopone 30% is the perfect solution for partial substitution of TiO2 in fillers due to its very soft nature and hardly any shrinkage properties.
It is suitable as an alternative to titanium dioxide when higher acid resistance is required, such as in adhesive joints and sealants.
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