What is the use of lithopone powder?

Chemical compound

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Color pigments used on the warship Vasa, with white lead second from left, bottom shelf

White lead is the basic lead carbonate 2PbCO3·Pb(OH)2.[1] It is a complex salt, containing both carbonate and hydroxide ions. White lead occurs naturally as a mineral, in which context it is known as hydrocerussite,[1] a hydrate of cerussite.[2] It was formerly used as an ingredient for lead paint and a cosmetic called Venetian ceruse, because of its opacity and the satiny smooth mixture it made with dryable oils. However, it tended to cause lead poisoning, and its use has been banned in most countries.[3]

Basic lead carbonate is produced by treating lead acetate with carbon dioxide and air.[4] In the laboratory procedure treats lead acetate with urea.[5] It occurs naturally as the mineral cerussite.[6] The compound has been characterized by X-ray crystallography, which confirms the formula. The structure is complicated, features two kinds of Pb(II) sites, those bonded to hydroxide and those bonded to carbonate and hydroxide.[7]

Related white lead compounds

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White lead compounds known as lead soap were used as additive for lubricants for bearings and in machine shops.[8] Lead soap was also used as an oil drying agent for paints made with drying oil or air drying paints made with alkyd resins. Lead is often used with cobalt driers. Lead free substitutes have been developed to replace this use of lead in paint.

A second basic lead carbonate is known with the formula 6Pb(CO3)·3Pb(OH)6·PbO.[7]

History

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What is commonly known today as the "Dutch method" for the preparation of white lead was described as early as Theophrastus of Eresos[9] (ca. 300 BC), in his brief work on rocks or minerals, On Stones or History of Stones. His directions for the process were repeated throughout history by many authors of chemical and alchemical literature. The uses of cerussa were described as an external medication and pigment.[10]

Clifford Dyer Holley quotes from Theophrastus' History of Stones[11] as follows, in his book The Lead and Zinc Pigments.

Lead is placed in earthen vessels over sharp vinegar, and after it has acquired some thickness of a sort of rust, which it commonly does in about ten days, they open the vessels and scrape it off, as it were, in a sort of foulness; they then place the lead over vinegar again, repeating over and over again the same method of scraping it till it has wholly dissolved. What has been scraped off they then beat to powder and boil for a long time, and what at last subsides to the bottom of the vessel is ceruse.[12]

Later descriptions of the Dutch process involved casting metallic lead as thin buckles and corroded with acetic acid in the presence of carbon dioxide. This was done by placing them over pots with a little vinegar (which contains acetic acid). These were stacked up and covered with a mixture of decaying dung and spent tanner's bark, which supplied the CO2, and left for six to fourteen weeks, by which time the blue-grey lead had corroded to white lead. The pots were then taken to a separating table where scraping and pounding removed the white lead from the buckles. The powder was then dried and packed for shipment or shipped as a paste.[13] One benefit of the process was that it was not necessary to dry the paste of white lead, removing its water. All that needed was to mill the paste with linseed oil, and the white lead would take up the oil and reject the residual water, to give white lead in oil. [citation needed]

Paints

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Can of Dutch Boy Paint, consisting of basic lead carbonate and linseed oil

White lead has been mostly supplanted in artistic use by titanium white, which has much higher tinting strength than white lead.[14] Critics argue that substitutes like zinc oxide and titanium dioxide are more reactive, become brittle, and can flake off.[15][16] White lead is less used by today's painters, not because of its toxicity directly; but simply because its toxicity in other contexts has led to trade restrictions that make white lead difficult for artists to obtain in sufficient quantities.[17] Winsor & Newton, the English paint company, was restricted in from selling its flake white in tubes and now must sell exclusively in 150 ml (5.3 imp fl oz; 5.1 US fl oz) tins.[18]

In the eighteenth century, white lead paints were routinely used to repaint the hulls and floors of Royal Navy vessels, to waterproof the timbers and limit infestation by shipworm.[19]

Other synonyms (as an art pigment)

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Among the synonyms for white lead are Berlin white, Cremnitz white, Dutch white lead, flake white, Flemish white, Krems white, London white, Pigment White 1, Roman white, silver white, slate white and Vienna white.[20]

See also

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Pairs Horses Chemical supply professional and honest service.

Additional reading:
titanium dioxide rutile grade tio2 r-960 paint price

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References

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Further reading

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• Gettens, R.J., Kühn, H. and Chase, W.T. "Lead White", in Roy, A., (Ed), Artists' Pigments, Vol 2, Oxford University Press, , pp. 67&#;81

• Lead white, Colourlex

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.

Pigment Names

Primary NamesEnglish: lithopone
French: lithopone
German: Lithopon
Italian: litopone
Russian: &#;&#;&#;&#;&#;&#;&#;
Spanish: lithoponeAlternate NamesEnglish: Barium zinc sulfate sulfide, Enamel White, barium zinc sulfate, barium zinc sulfide, zinc sulfide, barium sulfate mixture, Becton White, Charlton White, Zincolith, surya&#;s salt

History

The 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.

Composition

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.

Permanence and Stability

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 Listed

Physical 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
0. gal/lbRefractive Index:1.84Oil Absorption:21.5 grams oil / 100 grams pigmentSafety Information:Based on a toxicological review, there are no acute or known chronic health hazards with the anticipated use of this product. Always protect yourself against potentially unknown chronic hazards of this and other chemical products by avoiding ingestion, excessive skin contact, and inhaling spraying mists, sanding dust, and concentrated vapors. Contact us for further information or consult the MSDS for more information.

For a detailed explanation of the terms in the table above, please visit Composition and Permanence.

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