Fact-checked by Grok 2 weeks ago

Pigment

A pigment is a colored chemical compound, typically insoluble in water and common solvents, that imparts color to materials by selectively absorbing specific wavelengths of visible light while reflecting or transmitting others.^[1] This property arises from the pigment's molecular structure, which determines its interaction with light, distinguishing pigments from luminescent processes like fluorescence.^[2] Pigments are dispersed as fine particles in a medium, such as binders in paints or polymers in plastics, to provide opacity, tint, or hue without dissolving.^[3] Unlike dyes, which are soluble and penetrate substrates to color them molecularly, pigments function through surface adhesion or incorporation, offering greater resistance to fading and washing in applications like coatings and textiles.^[4] They are classified primarily as organic or inorganic based on composition. Inorganic pigments, often metal-based compounds like oxides or sulfides (e.g., titanium dioxide for whites or chromium oxide for greens), are prized for their chemical stability, heat resistance, and opacity, making them suitable for industrial uses such as automotive paints and construction materials.^[5] Organic pigments, composed mainly of carbon, hydrogen, nitrogen, and oxygen, provide vibrant colors and transparency but can be less durable to light or chemicals; examples include azo compounds for yellows and reds, and they dominate in printing inks and artists' colors.^[5] Within these categories, pigments may be natural—sourced from minerals, plants, or animals (e.g., indigo from plants)—or synthetic, engineered for consistency and performance.^[3] The history of pigments reflects human innovation in color technology, beginning with natural inorganic varieties like red ochre and black manganese used in Paleolithic cave art dating back over 40,000 years.^[6] Ancient civilizations advanced extraction and grinding techniques, employing lapis lazuli for ultramarine blue in Egyptian and Mesopotamian works around 2500 BCE.^[7] The era of synthetic pigments dawned in 1704 with the accidental discovery of Prussian blue (ferric ferrocyanide), the first modern inorganic synthetic, revolutionizing accessibility and affordability for artists and industry.^[7] The 19th century saw explosive growth in organic colorants, such as the first synthetic dye mauveine in 1856, driven by the coal tar dye industry, enabling brighter, more stable colors for mass production.^[8] In contemporary applications, pigments extend beyond aesthetics to functional roles, including UV protection in sunscreens, corrosion inhibition in coatings, and conductivity in electronics.^[9] Global production emphasizes sustainability, with research focusing on bio-based organics and low-toxicity inorganics to replace heavy metal variants like lead chromate.^[8] This evolution underscores pigments' indispensable role in art, manufacturing, and science, continually shaped by advances in chemical synthesis and environmental considerations.^[10]

Fundamentals

Definition and Classification

A pigment is a material that imparts color, opacity, or other visual properties to a medium by absorbing specific wavelengths of visible light, characterized as a solid that is insoluble in the application medium, such as water, oil, or polymers, forming suspensions rather than solutions.^[11]^[3] Unlike dyes, which are soluble colorants that dissolve molecularly in the medium to produce transparent coloration, pigments remain dispersed as fine particles, providing greater opacity and durability in applications like paints, inks, plastics, and textiles.^[5]^[3] Pigments are primarily classified by origin into natural and synthetic categories. Natural pigments are derived directly from mineral, vegetable, or animal sources without chemical alteration, such as ochre, a mineral-based earth pigment composed of iron oxides that has been used since prehistoric times for its red-yellow hues.^[3]^[12] Synthetic pigments, developed through industrial processes, offer consistent purity and vibrancy; for instance, charcoal black represents a carbon-based natural pigment obtained by charring wood, while modern synthetics expand this to controlled carbon variants.^[13]^[3] Another key classification is by chemical nature, distinguishing organic from inorganic pigments. Inorganic pigments typically contain metal ions or compounds, often sourced from minerals, providing stability and opacity; examples include iron oxide-based ochre for earth tones.^[5]^[3] Organic pigments, composed primarily of carbon, hydrogen, oxygen, and nitrogen and often featuring conjugated systems, may include coordination complexes with metals; they yield brighter colors and are frequently synthetic, such as phthalocyanine blue, a copper-phthalocyanine complex used in high-performance coatings and inks for its intense blue shade and lightfastness.^[5]^[14] Pigments are also categorized by function, encompassing colorants that primarily provide hue, fillers (or extenders) that enhance volume and mechanical properties without strong coloration, and functional additives that offer specialized effects like UV absorption to protect materials from degradation.^[15] For example, titanium dioxide serves as both a white colorant and UV absorber in coatings, while inert fillers like calcium carbonate reduce costs in plastics.^[15] The classification of pigments has evolved from early intuitive groupings based on source—such as mineral, vegetable, or animal origins in ancient texts—to more systematic schemes incorporating chemical composition and synthetic methods by the 19th and 20th centuries.^[16] This progression, driven by industrial advancements, shifted from utilitarian source-based lists to standardized taxonomies like those in the Colour Index, emphasizing reproducibility and performance.^[16]

Physical Principles

Pigments produce color through the selective absorption and reflection of light wavelengths within the visible spectrum, typically ranging from 400 to 700 nm. When white light interacts with a pigment particle, specific wavelengths are absorbed by the material's electronic structure, while others are reflected or transmitted, determining the perceived hue. For instance, a pigment appearing red absorbs shorter wavelengths like blue and green, reflecting longer red wavelengths back to the observer.^[11] The key molecular features responsible for this absorption are chromophores, which are functional groups of atoms within the pigment that facilitate electronic transitions upon light exposure. In organic pigments, color arises from conjugated systems—alternating single and double bonds that delocalize pi electrons, lowering the energy gap required for visible light absorption and shifting the absorption from ultraviolet to visible regions. In contrast, inorganic pigments derive their color from various electronic transitions, including d–d (ligand field) transitions in transition metal compounds, charge-transfer transitions between metal and ligand or between metals, and band-to-band transitions across the bandgap in semiconductors where the bandgap energy falls in the visible spectrum (typically producing colors from yellow to red as the bandgap narrows).^[17]^[18]^[19] The intensity of absorption in pigment dispersions follows the Beer-Lambert law, which quantifies how light attenuation relates to pigment concentration and path length, contributing to the material's opacity. The law is expressed as:

A = \epsilon l c

where A is the absorbance, \epsilon is the molar absorptivity (specific to the pigment and wavelength), l is the path length through the medium, and c is the concentration of the pigment particles. In pigment applications, such as coatings, this relationship models the cumulative absorption across multiple particle layers, predicting opacity buildup without light transmission.^[20] Beyond absorption, pigments exhibit optical properties including light scattering and refraction, which influence color perception and visual effects. Scattering occurs when light waves interact with pigment particles, redirecting them in various directions; the Tyndall effect specifically describes the scattering of shorter blue wavelengths by colloidal-sized particles (typically 10-1000 nm), enhancing perceived blueness in dilute suspensions. Refraction at particle surfaces can bend light paths, altering hue saturation. Particle size plays a critical role: larger particles (>500 nm) primarily scatter via reflection, yielding matte opacity, while smaller ones (<200 nm) promote diffraction, shifting colors toward shorter wavelengths and increasing transparency or iridescence due to wave interference.^[21]^[22]^[23] Unlike dyes, which dissolve molecularly in a medium to produce transparent solutions where light passes through with selective absorption, pigments remain insoluble particulates that scatter light extensively, resulting in inherent opacity even at low concentrations. This particulate nature prevents full light transmission, creating a suspended dispersion that masks underlying substrates.^[24]

Historical Development

Ancient and Traditional Pigments

The use of pigments dates back to prehistoric times, with evidence of pigment application dating back to approximately 100,000 years ago at Blombos Cave in South Africa, where an ochre-based mixture was used for symbolic or artistic purposes.^[25] In Europe, cave paintings provide further examples, such as those in Lascaux, France, dating to around 17,000 years ago, where red ochre derived from iron oxides was applied to depict animals and hand stencils.^[26] These early pigments were typically sourced from naturally occurring minerals, mixed with binders like animal fat or water to create rudimentary paints for wall decorations in protected caves.^[27] Among the key natural pigments employed in ancient and traditional art were earth colors, which originated from iron and manganese oxides found in clay deposits. Sienna, a yellowish-brown pigment in its raw form, was derived from iron oxide-rich soils in regions like Tuscany, while umber, darker and greener due to higher manganese content, was similarly extracted from natural earths and used for shading and depth in paintings.^[28] Lapis lazuli, ground into the vivid ultramarine blue, was primarily sourced from mines in Afghanistan's Badakhshan region dating back to the 7th millennium BCE, and its scarcity made it highly prized, especially during the Renaissance when it was reserved for depictions of the Virgin Mary's robes.^[29]^[30] Vermilion, a brilliant red obtained by grinding cinnabar (mercury sulfide, HgS), was valued for its intensity despite its toxicity from mercury content, and was applied in ancient Chinese lacquerware and Roman frescoes.^[31] Regional developments highlighted innovative sourcing and early synthesis of pigments. In ancient Egypt around 3000 BCE, malachite—a copper carbonate mineral—provided a bright green used in tomb decorations and cosmetics, while Egyptian blue, the world's first known synthetic pigment made from copper compounds, silica, and lime, was fired into a stable frit for use in murals and jewelry. In Mesoamerica, the Maya and Aztecs extracted cochineal red from the dried bodies of female cochineal insects (Dactylopius coccus) farmed on prickly pear cacti, producing a potent carminic acid dye for textiles, pottery, and codices as early as 700 BCE.^[32] Trade routes significantly influenced pigment availability, with the Silk Road facilitating the transport of lapis lazuli from Afghan mines to Europe and the Mediterranean, where it became a luxury commodity exchanged alongside silk and spices from the 1st century BCE onward.^[33] Similarly, Tyrian purple, a dye-pigment hybrid derived from the glands of thousands of Mediterranean sea snails (primarily Bolinus brandaris), was produced by Phoenician artisans and traded at exorbitant costs—equivalent to three times the price of gold in the Roman era—due to the labor-intensive extraction process involving fermentation of up to 12,000 mollusks per gram.^[34] Pigments held profound cultural significance beyond aesthetics, often integral to rituals, mummification, and cosmetics. In ancient Egypt, red ochre and green malachite were applied during embalming to symbolize vitality and rebirth, while black kohl (from galena or soot) and green eye paints were used in funerary masks and daily adornments to invoke protection from evil spirits.^[35] These materials appeared in grave goods, such as palettes for grinding pigments, underscoring their role in ensuring safe passage to the afterlife and personal beautification rituals.^[36]

Modern and Synthetic Pigments

The development of modern synthetic pigments began in the early 18th century with the accidental discovery of Prussian blue in 1704 by Johann Jacob Diesbach, marking the first synthetic pigment with the chemical formula Fe₄[Fe(CN)₆]₃.^[37] This deep blue iron hexacyanoferrate compound revolutionized color production by offering a stable, reproducible alternative to natural blues like indigo or lapis lazuli, enabling its widespread use in paints, textiles, and prints.^[38] Its synthesis from simple inorganic precursors demonstrated the potential of chemical methods to surpass natural limitations in hue intensity and availability.^[39] In the 19th century, further milestones included the 1809 invention of chrome yellow (PbCrO₄), a lead chromate pigment that provided a vibrant, opaque yellow for industrial applications such as paints and ceramics.^[40] This compound's high tinting strength and lightfastness made it a staple in the burgeoning paint industry during the Industrial Revolution.^[41] A pivotal advancement came in 1856 when William Henry Perkin synthesized mauveine, the first synthetic organic pigment, through oxidation of aniline while attempting to produce quinine.^[42] This breakthrough ushered in the era of aniline-based colors, offering unprecedented vibrancy and scalability for textiles and later paints, fundamentally shifting pigment production from extraction to synthesis.^[43] The 20th century saw innovations driven by advances in inorganic and organic chemistry. Titanium dioxide (TiO₂), commercialized as a pigment in 1916, transformed white pigmentation by providing superior opacity and non-toxicity compared to lead white, becoming the dominant white pigment in paints and coatings due to its high refractive index and UV stability.^[44] In the 1930s, phthalocyanine pigments emerged, with copper phthalocyanine yielding brilliant, stable blues and greens that excelled in lightfastness and chemical resistance, widely adopted in automotive and printing industries.^[45] The 1880s introduction of azo pigments, derived from diazo coupling reactions in organic chemistry, expanded the palette with cost-effective reds, yellows, and oranges, enhancing color range while improving solubility and application versatility. Polymer science further bolstered pigment stability in the mid-20th century by enabling encapsulation and dispersion techniques in resin binders, reducing fading and improving adhesion in coatings.^[46] The transition to synthetic pigments accelerated post-1970s due to environmental regulations, such as the U.S. EPA's 1978 ban on lead-based paints, which prioritized consistency, lower cost, and non-toxicity over traditional lead chromates and whites.^[47] Synthetics like TiO₂ and organic alternatives offered uniform particle size for better dispersion and reduced health risks, driving their dominance in consumer and industrial products.^[48] This shift enhanced production efficiency while mitigating toxicity concerns associated with heavy metals.^[49] Recent developments through 2025 have focused on nanomaterials, bio-based synthetics, and advanced optoelectronics. Nano-scale TiO₂ particles, refined since the 2010s, enhance pigment durability in paints by improving UV resistance and mechanical strength, with studies showing up to 30% better weatherability in coatings.^[50] Bio-based synthetic pigments, derived from microbial fermentation or plant extracts via synthetic biology, offer sustainable alternatives to petroleum-derived organics; for instance, engineered azaphilone pigments provide stable reds and purples with reduced environmental footprint. As of 2025, EU regulations have accelerated adoption of such bio-pigments in coatings, reducing reliance on synthetic organics by up to 20% in compliant industries.^[51]^[52] Quantum dot pigments, semiconductor nanocrystals like CdSe or InP, have advanced display technologies by 2025, enabling QLED screens with over 90% color gamut coverage and enhanced brightness for vibrant, energy-efficient visuals.^[53] These innovations prioritize sustainability and performance, addressing demands for eco-friendly, high-impact coloration.

Chemical Composition

Inorganic Pigments

Inorganic pigments are colored materials derived from minerals or synthetic metal compounds that impart color through their crystalline or amorphous structures, primarily used in applications requiring durability. These pigments are typically insoluble in common solvents and include classes such as metal oxides, sulfides, and chromates. Examples of metal oxides include iron(III) oxide (Fe₂O₃), which produces red hues due to its hematite structure, and zinc oxide (ZnO), a white pigment valued for its opacity.^[54]^[55] Sulfides like cadmium sulfide (CdS) yield bright yellow colors, while chromates such as lead chromate (PbCrO₄) have been historically used for yellow pigments but are now largely phased out due to environmental regulations.^[54]^[56] The color of inorganic pigments arises from electronic transitions influenced by crystal structures, lattice defects, and metal-ligand interactions within the solid matrix. In many cases, transition metal ions in specific coordination environments absorb visible light, leading to perceived color; for instance, in the spinel structure of cobalt aluminate (CoAl₂O₄), known as cobalt blue, the tetrahedral coordination of Co²⁺ ions causes d-d transitions that produce an intense blue hue. Lattice defects, such as vacancies or impurities, can further modulate the bandgap and absorption spectrum, enhancing color intensity or shifting wavelengths.^[57]^[58] Inorganic pigments offer advantages including exceptional thermal stability, resistance to chemicals and light, and long-term durability, making them suitable for harsh environments like outdoor coatings. However, they often contain heavy metals, leading to potential toxicity concerns; for example, cadmium- and lead-based pigments pose environmental and health risks upon release.^[55]^[59] Titanium dioxide (TiO₂) exemplifies structural variations affecting properties, with the rutile polymorph providing superior UV protection compared to anatase due to its higher refractive index and lower photocatalytic activity, which prevents degradation in polymer matrices. Carbon black, an amorphous form of elemental carbon (C), serves as a non-metal inorganic black pigment with high tinting strength and UV absorption, though it lacks a crystalline lattice.^[60] Identification of inorganic pigments commonly employs X-ray diffraction (XRD), which analyzes crystalline structures to distinguish phases like rutile from anatase or confirm spinel compositions, enabling precise characterization without sample destruction.^[61]

Organic Pigments

Organic pigments are carbon-based colorants derived from organic compounds, distinguished by their molecular structures that enable vibrant hues through conjugation and electronic transitions. These pigments encompass both synthetic and naturally occurring varieties, with synthetic ones dominating modern applications due to their tunable properties. Unlike inorganic pigments, which rely on crystal lattices for color, organic pigments achieve coloration primarily through delocalized pi-electron systems in their molecular frameworks.^[62] The core structures of organic pigments include azo compounds, polycyclic types, and phthalocyanines. Azo pigments, comprising about 59% of organic pigments, feature a central -N=N- azo linkage (Ar-N=N-Ar) flanked by aromatic rings, as seen in Hansa yellow (Pigment Yellow 1), which provides bright yellow tones.^[63]^[64] Polycyclic pigments, such as quinacridone reds and perylenes, consist of fused ring systems offering high stability and intense reds to violets; for instance, quinacridone (Pigment Violet 19) derives from anthraquinone scaffolds.^[65] Phthalocyanines, though often metal-complexed (e.g., copper phthalocyanine blue, Pigment Blue 15), are classified as organic due to their macrocyclic porphyrin-like cores, delivering deep blues and greens with exceptional durability.^[66] Natural organic pigments include indigo, a plant-derived indoxyl dimer with the formula C_{16}H_{10}N_{2}O_{2}, extracted from Indigofera species for blue shades, and alizarin, an anthraquinone (C_{14}H_{8}O_{4}) from madder root (Rubia tinctorum), renowned for its red dyeing properties.^[67]^[68]^[69] Organic pigments exhibit high tinting strength, allowing small quantities to impart intense color, and often superior transparency compared to inorganic counterparts, making them ideal for glazing and metallic effects. However, they face challenges in lightfastness, typically rated using the ASTM scale (I excellent to V poor) or the Blue Wool scale (1-8, with 8 excellent).^[70]^[71] Development of these pigments advanced through diazotization in azo synthesis, where aromatic amines are converted to diazonium salts via nitrous acid, followed by coupling with activated aromatics to form the azo bond; this process, established in the late 19th century, enabled mass production of vibrant synthetics. Modern high-performance organic pigments, like diketopyrrolopyrrole (DPP) reds, are engineered for automotive coatings, providing weather-resistant, transparent colors that meet stringent OEM standards for durability and gloss.^[72]^[73]^[74] Lake pigments represent a hybrid form where organic dyes are precipitated onto inorganic substrates like alumina or calcium salts to enhance insolubility and handling. For example, madder lake is produced by adsorbing alizarin from madder root extracts onto aluminum hydroxide, yielding a stable red pigment used historically in art and textiles. This method improves the pigment's resistance to bleeding while retaining the dye's vividness.^[75]^[76]^[77]

Biological Aspects

Pigments in Nature

Pigments in nature are ubiquitous across living organisms, serving as essential components for light absorption, protection, and signaling, with diverse chemical structures derived from biosynthetic pathways. These naturally occurring pigments exhibit a wide range of colors and functions, primarily categorized by their molecular frameworks such as porphyrins, carotenoids, flavonoids, and melanins.^[78] In plants, chlorophylls are the predominant green pigments, consisting of magnesium-porphyrin complexes that enable photosynthesis by absorbing red and blue wavelengths of light while reflecting green. Chlorophyll a and b, the most common variants, are localized in chloroplasts and are crucial for capturing solar energy in leaves, stems, and algae. Carotenoids, another major class, include β-carotene, an orange tetraterpenoid that acts as an accessory pigment in photosynthesis and provides antioxidant properties to protect against oxidative stress; these are found in roots, fruits, and flowers, contributing to yellow, orange, and red hues. Anthocyanins, water-soluble flavonoids, produce red, purple, and blue colors in flowers, fruits, and leaves, with their hue shifting based on pH—appearing red in acidic conditions and blue in alkaline ones—due to structural changes in their anthocyanidin core.^[79]^[80]^[81] Animal pigments often derive from modified amino acids or heme breakdown products, providing coloration for integumentary structures. Melanins are polymeric pigments synthesized from tyrosine, with eumelanin producing black to brown shades through indolequinone units for UV protection and structural integrity in skin, hair, and eyes, while pheomelanin yields red-yellow tones via benzothiazine intermediates, commonly seen in feathers and fur. Bilins, linear tetrapyrroles derived from heme catabolism, include biliverdin and bilirubin; biliverdin imparts green or blue colors to bird eggshells and insect exoskeletons, serving as a waste product with antioxidant roles, whereas bilirubin appears yellow in certain vertebrates.^[82]^[83] Microbial pigments display remarkable diversity, particularly in bacteria adapted to extreme environments. Bacteriochlorophylls, analogous to plant chlorophylls but with reduced porphyrin rings, are magnesium-containing bacteriochlorins that facilitate anoxygenic photosynthesis in purple and green sulfur bacteria, absorbing infrared light for energy capture in low-oxygen habitats. Prodigiosin, a red tripyrrole pigment produced by Serratia marcescens and other gammaproteobacteria, features a tripyrrole structure consisting of three pyrrole rings and is secreted extracellularly, often in response to environmental stressors.^[84]^[85] The extraction of natural pigments has ancient roots, with early human societies utilizing plant sources for dyes; for instance, henna (Lawsonia inermis) yields lawsone, a red-orange naphthoquinone extracted from leaves, used since at least 2500 BCE in ancient Egypt and India for body art and fabric coloration through simple aqueous or acidic processing.^[86]^[87] Evolutionarily, natural pigments have played key roles in adaptation, with chlorophylls emerging early in photosynthetic lineages to harness light for energy, carotenoids aiding in photoprotection and signaling ripeness in fruits to attract dispersers, and animal melanins and bilins evolving for camouflage against predators or mating displays through sexual selection, as seen in the vivid carotenoid-based plumage of birds that balances concealment and conspicuousness.^[88]^[89]

Functions and Applications

Biological pigments serve essential roles in organisms, primarily facilitating energy capture, sensory perception, and protection against environmental stressors. In plants, chlorophyll enables photosynthesis by absorbing light energy, particularly in the blue and red wavelengths, to convert carbon dioxide and water into glucose and oxygen, supporting plant growth and oxygen production in the atmosphere.^[90] Carotenoids, another key class of pigments, act as accessory pigments in photosynthesis while also functioning as antioxidants to neutralize reactive oxygen species generated during light exposure, thereby preventing cellular damage in plants and animals.^[91] In animals, pigments contribute to vision and defense mechanisms. The retinal pigment epithelium (RPE) in the eye absorbs stray light and supports the visual cycle by recycling retinal, a vitamin A derivative essential for phototransduction in rod and cone cells, enabling light detection and image formation.^[92] Melanin, concentrated in skin, hair, and eyes, provides ultraviolet (UV) radiation shielding by absorbing UV photons and dissipating energy as heat, reducing DNA damage and the risk of skin cancer in humans and other vertebrates.^[93] Animal adaptations often leverage pigments for survival and communication. Structural coloration arises from nanoscale structures interacting with pigments, producing iridescence in peacock feathers through thin-film interference that reflects specific wavelengths, aiding mate attraction and species recognition without relying solely on chemical pigments.^[94] Aposematic coloration uses bright pigments, such as those in poison dart frogs, to signal toxicity or unpalatability to predators, enhancing survival by promoting learned avoidance behaviors.^[95] Extracted biological pigments find applications in human health and industry. Beta-carotene, sourced from carrots and other vegetables, serves as a natural food colorant and vitamin A precursor in supplements, helping prevent deficiency-related conditions like night blindness in populations with limited dietary intake.^[96] In cosmetics, carmine derived from cochineal insects provides a stable red hue for lipsticks and blushes, approved by regulatory bodies for safe use in external applications.^[97] Curcumin, a yellow pigment from turmeric, exhibits anti-inflammatory effects by inhibiting pathways like NF-κB and COX-2, supporting its use in pharmaceuticals for managing conditions such as arthritis and metabolic syndrome.^[98] Advancements in biotechnology have expanded pigment applications through genetic engineering. The improved Golden Rice 2, developed in the mid-2000s and approved for release in the Philippines in 2021, incorporates a maize-derived psy gene along with a bacterial gene for carotenoid biosynthesis into rice endosperm, producing beta-carotene (23–35 μg/g dry weight) to combat vitamin A deficiency in rice-dependent regions. Regulatory approval was granted in the Philippines in 2021, with commercial distribution beginning in 2022; as of 2025, it is being distributed in rice-dependent regions, though adoption faces challenges from anti-GMO sentiments.^[99]^[100] Despite these benefits, extracting biological pigments poses sustainability challenges. Astaxanthin from microalgae like Haematococcus pluvialis requires resource-intensive cultivation and extraction processes, leading to high costs and environmental concerns from energy use in production, prompting research into more efficient, eco-friendly methods to avoid overexploitation of natural sources.^[101]

Production and Properties

Manufacturing Processes

The manufacturing of inorganic pigments typically involves precipitation, calcination, and milling to achieve desired chemical composition and particle characteristics. In the sulfate process for titanium dioxide (TiO₂), a prominent white pigment, ilmenite ore is digested with concentrated sulfuric acid to form titanyl sulfate, which is then hydrolyzed in water to precipitate hydrated titanium dioxide (TiO₂·nH₂O). This precipitate is filtered, washed to remove impurities, and subsequently calcined at temperatures around 800–1000°C to dehydrate and form the anhydrous rutile or anatase crystal structure.^[102] Calcination, a high-temperature decomposition step, is essential for many inorganic pigments, including complex inorganic colored pigments (CICPs) such as spinel or zircon-based oxides, where precursor mixtures of metal salts or oxides are heated to 1000–1400°C in a solid-state reaction to form stable, heat-resistant crystals with vibrant colors.^[103] Following synthesis, milling—often using ball mills, attritors, or classifier mills—reduces particle size and breaks down agglomerates, ensuring uniform dispersion and optimal light-scattering properties for applications like paints and coatings.^[104] Organic pigments are synthesized through targeted chemical reactions tailored to their molecular structures. Azo pigments, which dominate the yellow, orange, and red color ranges, are produced via azo coupling, where an aromatic primary amine is diazotized with sodium nitrite in acidic conditions to form a diazonium salt, which then reacts with an electron-rich coupling component such as a naphthol or amine to yield the colored azo compound; this process is conducted at controlled temperatures (0–5°C for diazotization) to prevent decomposition.^[105] For phthalocyanine pigments like copper phthalocyanine blue (Pigment Blue 15), the synthesis involves cyclization of phthalic anhydride with urea and a copper(II) salt (e.g., copper chloride) under high-temperature conditions (150–250°C) in the presence of a catalyst like ammonium molybdate, forming the macrocyclic structure in a solvent such as nitrobenzene or via a solvent-free fusion method.^[14] Post-processing steps refine raw pigments for industrial compatibility and performance. Dispersion involves incorporating the pigment powder into liquid vehicles (e.g., resins or solvents) using high-shear mixers or bead mills to create stable suspensions that prevent settling and ensure even color distribution in end products.^[106] Surface treatments, such as coating with silane coupling agents (e.g., triethoxycaprylylsilane), modify the pigment surface to enhance compatibility with organic binders, improve hydrophobicity, and reduce agglomeration by forming covalent bonds between inorganic particles and polymer matrices.^[107] Micronization further controls particle size to a typical range of 1–10 μm through techniques like jet milling or fluidized-bed mills, optimizing opacity, tinting strength, and flow properties while minimizing dust and improving handling.^[108] Quality control in pigment manufacturing relies on spectroscopic techniques to verify purity and consistency. Techniques such as near-infrared (NIR) spectroscopy and Fourier-transform infrared (FTIR) spectroscopy analyze molecular composition and detect impurities non-destructively, enabling real-time monitoring of reaction progress and final product specifications like color strength and absence of contaminants.^[109] Environmental considerations address waste from hazardous processes, such as the traditional mercury-based production of vermilion (cinnabar, HgS); mercury-free alternatives include cadmium red (PR108) or modern organic pigments like pyrrole red (PR254), which replicate the hue without toxic heavy metals.^[110] The scale of pigment production has evolved from batch reactors, common in early 20th-century methods, to continuous flow processes post-1950s, particularly for high-volume pigments like TiO₂ via the chloride process and azo dyes, enabling higher throughput, reduced waste, and consistent quality through automated control of reaction parameters.^[111]

Figures of Merit

Figures of merit for pigments encompass standardized metrics that quantify their performance in applications such as paints, coatings, and inks, enabling comparisons of quality, efficiency, and suitability across formulations. These metrics evaluate aspects like color development, coverage, durability, and handling properties, often through protocols established by organizations such as ASTM International and the International Organization for Standardization (ISO). By focusing on these quantifiable attributes, manufacturers and users can select pigments that meet specific end-use requirements without relying on subjective assessments.^[112] Tinting strength refers to a pigment's capacity to impart color to a medium, such as a vehicle or binder, and is typically measured relative to a standard pigment under controlled conditions. This property is crucial for determining how efficiently a pigment can achieve desired hues with minimal quantity, influencing formulation costs and color consistency. For white pigments, tinting strength is assessed visually by comparing the color of a tint (pigment mixed with a standard blue pigment) against a reference, as outlined in ASTM D332.^[113] In practice, higher tinting strength allows for brighter, more saturated colors at lower concentrations, with measurements often involving spectrophotometric analysis for precision in chromatic pigments.^[114] Hiding power, also known as opacity, measures a pigment's ability to obscure or cover an underlying substrate, preventing the background color from showing through the applied layer. It is particularly important in coatings where uniform appearance over varied surfaces is required, such as in architectural paints. Hiding power is quantified using the contrast ratio, defined as R = \frac{R_b - R_w}{R_b + R_w}, where R_b and R_w represent the reflectance of the coating over black and white substrates, respectively; a value approaching 1 indicates near-complete opacity. This metric is evaluated through reflectometry in standards like ASTM D2805, which applies to liquid paints and assesses hiding at a specified film thickness.^[115] Lightfastness evaluates a pigment's resistance to color fading upon exposure to light, a critical factor for longevity in indoor and outdoor applications. It is commonly rated on the Blue Wool Scale, ranging from 1 (least resistant, fades quickly) to 8 (highly resistant, minimal change after prolonged exposure), based on comparison to standardized blue-dyed wool references under controlled illumination. This scale is formalized in ISO 105-B02, which simulates daylight exposure using xenon arc or filtered mercury lamps. For exterior uses, weatherfastness extends lightfastness to include effects from moisture, temperature cycles, and UV radiation, often tested via accelerated weathering protocols that correlate to real-world durability.^[116] Additional metrics include dispersibility, which assesses the ease with which a pigment incorporates into a medium without agglomeration, influencing uniformity and processing efficiency; this is evaluated through methods like Hegman gauge fineness of grind or dynamic light scattering for particle distribution. Bleed resistance measures a pigment's tendency to migrate or dissolve into adjacent layers or solvents, preventing color bleeding in multi-layer coatings, and is tested by solvent extraction as per ASTM D279. Toxicity indices, such as the median lethal dose (LD₅₀), quantify acute safety, with values exceeding 5000 mg/kg (oral, rat) indicating low mammalian toxicity for many commercial pigments, derived from standardized OECD or EPA guidelines.^[117]^[118]^[119] Testing standards from ISO and ASTM provide the frameworks for these evaluations, ensuring reproducibility across laboratories. For instance, the oil absorption value, expressed in grams of oil per gram of pigment, indicates the amount of vehicle required to wet the pigment particles fully, affecting viscosity and film properties; it is determined by spatula rub-out in ASTM D281 or mechanical kneading in ASTM D1483. These protocols, part of broader series like ISO 787 for general pigment tests, allow for batch-to-batch consistency and performance prediction in end products.^[120]

Industrial and Practical Uses

Standards and Specifications

The Colour Index International (CI) system serves as the global standard for classifying dyes and pigments, assigning unique identifiers based on chemical constitution and color properties to ensure consistency across industries. For instance, Pigment Blue 15 (PB15) designates copper phthalocyanine blue, a widely used organic pigment valued for its stability and tinting strength.^[121]^[122] Safety regulations govern pigment use to mitigate health and environmental risks, with the European Union's REACH framework (Regulation (EC) No 1907/2006) restricting hazardous substances, including certain azo pigments that may release carcinogenic aromatic amines under Annex XVII, entry 43. In the United States, the Food and Drug Administration (FDA) approves pigments for food-contact materials under 21 CFR Parts 70-82 and 178.3297, requiring safety demonstrations for colorants in packaging to prevent migration into food.^[123]^[124] Industry-specific standards address performance in targeted applications; for example, ASTM D476 classifies dry pigmentary titanium dioxide products into types suitable for architectural and automotive coatings based on composition and opacity. In printing, ISO 12647 specifies process parameters for color reproduction in offset lithography, including ink density and hue targets for pigment-based formulations to achieve standardized output.^[125] Purity specifications emphasize contaminant control and physical properties, with the Ecological and Toxicological Association of Dyes and Organic Pigments Manufacturers (ETAD) recommending limits such as less than 100 ppm for lead in organic pigments to minimize toxicity risks. Particle size distributions are standardized via ASTM D1366, which outlines reporting methods like mean diameter and percentiles to predict dispersion and optical performance in formulations.^[126] International harmonization has advanced post-2020 through updates promoting sustainable pigments, including bio-renewable content requirements tested under ASTM D6866, which measures biobased carbon percentages to support eco-friendly alternatives in global supply chains.

Visual Representation and Swatches

Printed swatches serve as standardized physical representations of pigment colors, typically in the form of cards or books where pigments are applied as inks on paper substrates. These swatches account for substrate absorption, which influences the final color appearance by affecting how pigments interact with the paper's surface and fibers. The Pantone Matching System (PMS), for instance, provides such printed guides with specific formulations to ensure consistent reproduction across printing processes.^[127]^[128] Plastic and material swatches offer representations tailored to non-paper media, often created as molded samples in polymers like polypropylene to demonstrate pigment dispersion effects within solid matrices. These are particularly useful in design fields for visualizing how pigments behave in coatings and plastics, where light scattering and embedding alter color perception. The RAL Plastics standard exemplifies this approach, using multifunctional plates to translate traditional paint shades into plastic-compatible formats for precise communication in manufacturing.^[129]^[130] Digital swatches represent pigment colors through computational models in design software, commonly using RGB for screen displays or CMYK for print simulations. Tools like Adobe Color allow users to generate and save these swatches, converting between color spaces while preserving relative hues. However, digital representations face gamut limitations, as RGB can encompass a broader range of colors than CMYK, leading to inaccuracies when translating vibrant pigment shades to print. Additionally, metamerism poses a challenge, causing colors to shift under different lighting conditions due to discrepancies between digital spectral simulations and physical pigment reflectance.^[131]^[132]^[133] To achieve precise pigment color matching, spectrophotometry measures reflected light across the visible spectrum, enabling calculations of color differences in standardized spaces like CIE Lab. In this system, the color difference ΔE quantifies perceptual variance between samples using the formula:

\Delta E = \sqrt{\Delta L^2 + \Delta a^2 + \Delta b^2}

where ΔL represents lightness difference, Δa is the red-green axis variation, and Δb is the yellow-blue axis variation; values below 1 indicate differences imperceptible to the human eye. This technique is essential for verifying pigment consistency in production.^[134]^[135] Despite these methods, visual representations of pigments exhibit limitations due to variability in viewing conditions, such as illumination angle and observer perception, which can alter apparent color. Historical swatch books, like the 1809 collection of 276 water-color samples with notes on pigment properties, illustrate these challenges by documenting inconsistencies in early standardized displays.^[136]

Economic and Societal Impact

Market and Trade

The global pigment market was valued at approximately $30 billion in 2024 and is projected to reach around $40 billion by 2030, growing at a compound annual growth rate (CAGR) of about 5%. The market reached approximately USD 31.93 billion in 2025.^[137]^[138] White pigments, particularly titanium dioxide (TiO₂), dominate the market with roughly 50% share due to their widespread use in providing opacity and brightness.^[139] Major producers include multinational companies such as BASF SE, Clariant AG, and DIC Corporation, which specialize in high-performance and organic pigments.^[140] China serves as the primary production hub, accounting for about 40% of global output, while Europe focuses on premium organic pigments for specialized applications.^[138] Post-World War II economic recovery spurred significant export booms in the chemical sector, including pigments, as industrialized nations like the United States and Germany expanded production to meet reconstruction demands in construction and manufacturing.^[141] In recent decades, trade dynamics have been shaped by tariffs, such as the U.S. anti-dumping duties on Chinese TiO₂ imports imposed starting in 2015, which ranged from 22% to 26% and continued through 2025 amid ongoing trade tensions.^[142] Demand is primarily driven by the paints and coatings sector, which accounts for about 60% of consumption, followed by plastics at 20% and inks at 10%, with emerging growth in eco-friendly, low-VOC pigments fueled by regulatory and consumer preferences for sustainability.^[143] The supply chain relies heavily on raw materials like ilmenite for TiO₂ production, sourced mainly from mining operations in Australia, South Africa, and China, but disruptions such as the 2022 energy crises in Europe and Asia led to sharp price increases of up to 20-30% due to higher production costs and logistics challenges.^[144]

Environmental and Health Considerations

The production and use of pigments pose significant health risks, primarily through inhalation of fine particulate matter and exposure to heavy metals. Carbon black, a common black pigment, is classified as possibly carcinogenic to humans (Group 2B) by the International Agency for Research on Cancer due to sufficient evidence of carcinogenicity in experimental animals and limited evidence in humans from occupational exposure via inhalation. Heavy metal-based pigments, such as those containing cadmium, present toxicity risks including kidney damage and carcinogenicity; for instance, cadmium pigments have been restricted in toys under the EU Toy Safety Directive 2009/48/EC, which limits the migration of cadmium to 1.3 mg/kg in dry, brittle, powder-like or pliable toy materials and 0.3 mg/kg in liquid or sticky toy materials, with 17 mg/kg for scraped-off paint, to prevent child exposure, with the directive entering force in July 2011 following preparatory restrictions from 2007.^[145] Environmental impacts from pigment production include pollution from mining inorganic pigments and emissions during synthesis. Titanium dioxide (TiO2) mining generates tailings that contaminate water bodies and soils with heavy metals and acids, adversely affecting benthic fauna and aquatic ecosystems through sedimentation and toxicity.^[146] Organic pigment synthesis often releases volatile organic compounds (VOCs) such as toluene and xylene, contributing to air pollution and photochemical smog formation during solvent-based processes.^[147] Additionally, pigment-laden paint waste degrades into microplastics, with paint particles identified as a major source of microplastic pollution in marine and terrestrial environments, releasing toxic additives and pigments that bioaccumulate in food chains.^[148] Efforts to mitigate these issues incorporate green chemistry principles, such as shifting to water-based processes that reduce solvent use and VOC emissions by up to 80% compared to traditional organic synthesis.^[149] In the 2020s, there has been increased adoption of non-toxic alternatives like bismuth vanadate yellow (Pigment Yellow 184), which offers comparable opacity, lightfastness, and tinting strength to cadmium yellow without the heavy metal toxicity, driven by regulatory pressures and sustainability demands in paints and coatings.^[150] Regulations address these concerns through exposure limits and assessment frameworks. The U.S. Occupational Safety and Health Administration (OSHA) sets a permissible exposure limit (PEL) for TiO2 at 15 mg/m³ as an 8-hour time-weighted average for total dust, with recommendations for lower levels for respirable fractions to minimize lung irritation and potential carcinogenicity.^[151] Lifecycle assessments (LCAs) for pigments follow ISO 14040 standards, evaluating cradle-to-grave impacts including resource extraction, emissions, and waste to guide sustainable production, as applied in studies of organic pigment manufacturing.^[152]^[153] A notable case study is Minamata disease in 1950s Japan, where industrial mercury discharges contaminated fish, causing severe neurological poisoning in over 2,000 people; although stemming from chemical production, this incident highlighted mercury's toxicity in various applications, including historical pigments like vermilion (mercury sulfide), and spurred the 2013 Minamata Convention on Mercury, leading to phased reductions and phase-outs of mercury use in products and processes on timelines such as 2025 for certain items and 2034 for dental amalgam, with global efforts continuing as of 2025.^[154]

References

[1]
Bacterial Pigments and Their Multifaceted Roles in Contemporary ...
Feb 28, 2023 · Overview of Natural Pigments, Plant Pigments and Microbial Pigments. A pigment can be defined as a chemical compound capable of absorbing a ...
[2]
Pigment Definition and Chemistry - ThoughtCo
Jun 10, 2025 · A pigment is a substance that appears a certain color because it selectively absorbs wavelength of light. While many materials possess this ...Missing: authoritative | Show results with:authoritative
[3]
What's in Your Paintbox? - American Chemical Society
Feb 1, 2023 · A pigment is a substance, insoluble in water or in the liquid medium of paint, which imparts color. Historically, inorganic compounds were used to infuse color ...Missing: definition | Show results with:definition
[4]
GENERAL INTRODUCTION TO THE CHEMISTRY OF DYES - NCBI
Pigments can be used to colour any polymeric substrate but by a mechanism quite different from that of dyes, in that surface-only colouration is involved unless ...
[5]
Pigments, Dyes, Inks and Glazes - The Chemistry of Art
One common way to classify pigments is by whether they contain metals or not. Most inorganic pigments contain metals while organic pigments, which are composed ...Missing: authoritative | Show results with:authoritative
[6]
Historical Pigments: A Survey of Analytical Chemical Archaeometric ...
Jun 15, 2015 · The adoption of mineral pigments for artistic expression can be traced back to the paintings of the Magdalenian and Cro-Magnon cultures of ...
[7]
A History of Pigment Use in Western Art Part 2 | PCI Magazine
Oct 1, 2004 · The industrial history of pigments can be said to have begun between 1704 and 1710 with the synthesis of the first synthetic inorganic pigment: Prussian blue.New Pigments · Beginnings Of Modern Art · Modern Pigments
[8]
The Chemistry of Pigments and How Scientists Prevent Color ...
Jun 23, 2020 · Pigments are the compounds added to materials to give them color. This deceptively simple application has shaped our perception of the world.Missing: definition | Show results with:definition
[9]
Inorganic vs. Organic Pigments | Differences & Uses - Brenntag
Organic pigments are transparent, while inorganic pigments are opaque. This means that a single layer of organic pigment may not be sufficient to create a good ...Missing: authoritative | Show results with:authoritative
[10]
Stabilizing and Modulating Color by Copigmentation: Insights from ...
Copigmentation can be defined as (i) the formation (in the presence or absence of metal ions) of noncovalent complexes involving an anthocyanin or anthocyanin- ...
[11]
Pigment - an overview | ScienceDirect Topics
A pigment is a molecular substance that absorbs specific light wavelengths, and is a colored, black, white, or fluorescent solid, insoluble in the medium.
[12]
Ochre - The Oldest Known Natural Pigment in the World - ThoughtCo
Jul 3, 2019 · Ochre is a natural pigment made from iron oxide, used by artists for thousands of years. · In prehistoric times, ochre was used for art, medicine ...
[13]
Charcoal black - ColourLex
Charcoal black is finely ground material obtained by carbonizing (charring) wood. It is very stable as are all carbon blacks and is absolutely lightfast.
[14]
What is Phthalocyanine Blue Pigment? - Ranbar
Phthalocyanine blue pigment is a synthetic organic blue pigment derived from copper phthalocyanine, used in coatings, inks, plastics, and textiles.
[15]
The world of inorganic pigments | ChemTexts
May 30, 2022 · The reason why functional pigments are classified as pigments is because of their similar morphological and application–technical properties.
[16]
[PDF] A Taxonomy of Historical Pigments - Art Is Creation
The classification of pigments too, has been addressed in the past and examination of the literature shows that there are numerous pigment lists, both ...
[17]
What is a Chromophore? | Functional Groups and Examples - Ossila
A chromophore is a molecule or section of a larger compound that absorbs and reflects specific electromagnetic radiation which we observe as colour.
[18]
https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Organic_Chemistry_(Morsch_et_al.)/14:_Conjugated_Compounds_and_Ultraviolet_Spectroscopy/14.09:_Conjugation%2C_Color%2C_and_the_Chemistry_of_Vision
[19]
[PDF] New Inorganic Pigments from Mineral Structures
May 19, 2022 · 6. Therefore, colors obtained from bandgap absorbance do not correspond to the reciprocal color (Figure 1.3) Because of this, bandgap ...
[20]
[PDF] Using Beer's Law to Model - American Coatings Association
Although some automotive pigments function by reflecting or scattering, we demonstrate here that log-linear models similar to Beer's Law for absorption can.Missing: opacity | Show results with:opacity
[21]
Optical Properties of Pigments: Absorption and Scattering
Mar 9, 2022 · Two phenomena govern both color and opacity of a coating: absorption and/or scattering of visible light by the pigment particles that are within that coating.
[22]
[PDF] How Noniridescent Colors Are Generated by Quasi ... - Prum Lab
For example, the blue color exhibited by feathers of numerous birds was attributed to the Tyndall effect. According to the Rayleigh law, the scattering ...<|control11|><|separator|>
[23]
Scattering of Light by Pigment Particles - Optica Publishing Group
It is immediately evident that the particles in the diffraction range will exercise the main control of the optical properties of the pigment.
[24]
[PDF] Color Science in the Examination of Museum Objects
pigments. Dyes are distinguished from pigments by their solubility in a solvent or medium; the resulting dye solutions are clear and transparent. When a dye ...Missing: insolubility | Show results with:insolubility
[25]
The Colorful History of Paint | EarthDate
Jun 4, 2018 · The oldest archaeological evidence of paint making was found in the Blombos Cave in South Africa. An ochre-based mixture was dated at 100,000 ...
[26]
Gems on Canvas: Pigments Historically Sourced from Gem Materials
The famous Hall of the Bulls in the Lascaux Caves contains early cave paintings rendered in red ochre. Photo by JoJan/CC BY 4.0. Hands stenciled using red ...
[27]
Prehistoric pigments | Resource - RSC Education
In the Lascaux cave in France there are red and yellow hydrated and ... One curious thing is that many of the early cave paintings are often red or black.Missing: earliest | Show results with:earliest
[28]
https://www.naturalpigments.eu/artist-materials/umber-exploring-natural-brown-earth-pigment
[29]
Pigments through the Ages - History - Ultramarine - Webexhibits
First used in 6th century Afghanistan, the pigment found its most extensive use in 14th and 15th century illuminated manuscripts and Italian panel paintings, ...
[30]
Cinnabar: Red, Beautiful — and Toxic - Science | HowStuffWorks
Feb 27, 2024 · Cinnabar is born in the shallow veins of blazing volcanic rock. It has historically been used as a pigment called vermilion for millennia.
[31]
Cochineal (resource) - NCMALearn - North Carolina Museum of Art
Early Maya people developed ways of protecting the delicate insects and farming them to improve the red dye produced. In the Aztec language Nahuatl, the ...
[32]
Historical Reading List: Lazurite (Lapis Lazuli) from Afghanistan and ...
Dec 14, 2020 · It represented the western portion of the so-called “Silk Road”, and archaeological evidence suggests that it was in operation as a trading ...
[33]
Ancient Color | Creating Purple - University of Michigan
In Rome during the 1st century CE, a pound of Tyrian purple dye cost about half a Roman soldier's annual salary, or the equivalent of the cost of a diamond ...
[34]
Green Pigments | Mummy Portraits of Roman Egypt - Getty Museum
Found on Egyptian tomb paintings, malachite is perhaps one of the oldest known green pigments. ... Egyptian blue that appeared green. Although copper-based ...Missing: BCE | Show results with:BCE
[35]
Highlights from the Collection: Mummies
Around the body were grouped clay jars containing food and drink and a slate palette with grinding stone, used to pulverize mineral pigments for cosmetics. All ...<|control11|><|separator|>
[36]
[PDF] Synthesis and Fading of Eighteenth-century Prussian Blue Pigments
May 1, 2013 · Prussian blue, a hydrated iron(III) hexacyanoferrate(II) complex, is a synthetic pigment discovered in Berlin in 1704.
[37]
Prussian Blue - Architectural Conservation Laboratory
Prussian blue, discovered in the early 18th century, is one of the first synthetic pigments widely used by artists. · The discovery of Prussian blue is ...
[38]
Characterization and utilization of Prussian blue and its pigments
Nov 15, 2016 · This review deals with our long-range goal of determining why the Prussian blue pigments, typically either the soluble KFe III [Fe II (CN) 6 ]·xH 2 O or the ...
[39]
X-Ray fluorescence as a method of characterizing inorganic pigment ...
Chrome yellow, PbCrO4, Discovered in 1809CE. Zinc yellow, ZnCrO4, Discovered in 1809CE. Chromium oxide green, Cr2O3, Discovered in 1809CE ... (Pigment Compendium ...
[40]
historic wallpaper technology - National Park Service
Apr 26, 2007 · For example, the presence of Chrome Yellow (PbCrO4) indicates a date after 1809. Chrome Yellow was discovered in 1797, but the formula was ...
[41]
A colorful chemistry revolution: How the 19th century dye industry ...
Oct 1, 2025 · In 1856, an accident led to the very first synthetic dye, launching ... Remember that Perkin got his patent for mauveine in 1856. It ...
[42]
Perkin s mauve: The history of the chemistry - Academia.edu
William Perkins discovered mauveine on April 28, 1856, marking a pivotal moment in dye chemistry. Perkin's initial goal was to synthesize quinine but ...
[43]
Critical Review of Public Health Regulations of Titanium Dioxide, a ...
Production of TiO2 was started in 1916 by the Titan Company (Norway) and what is now known as NL Industries (United States). TiO2 was first produced in the ...
[44]
OCCUPATIONAL EXPOSURES IN PAINT MANUFACTURE ... - NCBI
The largest single advance in pigment technology after the First World War was the discovery in the 1930s of phthalocyanine blue (Monastral blue) and, later ...
[45]
[PDF] Stuart Croll NDSU 2009 1 History of Paint Science and Technology ...
1916. First type of titanium dioxide pigment made. Farup and Jebsen in Norway ... Berke, “The invention of blue and purple pigments in ancient times,” Chem.
[46]
Protect Your Family from Sources of Lead | US EPA
Dec 6, 2024 · In 1978, the federal government banned consumer uses of lead-based paint, but some states banned it even earlier. Lead-based paint is still ...Missing: pigment | Show results with:pigment
[47]
Titanium Dioxide - Final Report - epa nepis
Production and Consumption Titanium dioxide was first produced in the U.S. in 1916 by the Titanium Pigment Company. In 1925 (after the National Lead Company ...
[48]
[PDF] Titanium - USGS Publications Warehouse
Dec 17, 2017 · Although lead has similar whitening properties, titanium dioxide pigment replaced lead as a whitener because of public health issues related ...
[49]
Optimizing the effect of TiO2 nano powder in water-based paint ...
Oct 23, 2025 · The TiO2 nano powder can significantly enhance these paints' optical and durability characteristics. This literature review delves into the ...
[50]
Recent Findings in Azaphilone Pigments - PMC - NIH
This review, covering the literature from 2020 onwards, focuses on the state-of-the-art of azaphilone dyes, the global market scenario, new compounds isolated ...
[51]
Nanoscience in Action: Unveiling Emerging Trends in Materials and ...
Quantum dots (QDs) are semiconductors-based nanomaterials with numerous biomedical applications such as drug delivery, live imaging, and medical diagnosis ...
[52]
Colorants: Organic and Inorganic Pigments - ScienceDirect.com
Even though, inorganic pigments lack the intensity and brightness of color of typical organic pigments, they are superior over the latter in terms of providing ...
[53]
Inorganic Pigment - an overview | ScienceDirect Topics
Zinc chromate, zinc oxide, chromium oxide, barium chromate, and cadmium sulfide are also used as inorganic pigments. Titanium dioxide (TiO2) is now the most ...
[54]
Hazardous metal additives in plastics and their environmental impacts
Inorganic pigments are centered around the intensely colored, calcined compounds of CdS and PbCrO4. Cadmium sulfide is bright yellow, with excellent thermal ...
[55]
YInMn blue - 200 Years in the making: New intense inorganic ...
This review chronicles the historical importance of inorganic pigments, reviews the origin of color in solids and highlights recent advancements in designing ...
[56]
Preparation and coloring mechanism of MAl2O4/CoAl2O4/quartz ...
Jan 15, 2022 · Cobalt aluminate (CoAl2O4) is an eco-friendly mixed metal oxide blue pigment with spinel structure, excellent thermal and chemical stability, ...
[57]
Heavy metals in cosmetics and tattoos: a review of historical ...
Inorganic tattoo pigments are naturally occurring mineral compounds such as metal oxides (hematite Fe2O3), salts, and minerals (cinnabar HgS). Synthetic ...<|separator|>
[58]
Roles of anatase and rutile TiO2 nanoparticles in photooxidation of ...
Anatase was found to be a photosensitiser that accelerates photooxidation of PU, while rutile acted as an effective stabilizer retarding photooxidation of PU.
[59]
Historical pigments: a collection analyzed with X-ray diffraction ...
The main objective of this work is the identification of inorganic pigments with X-ray diffraction analysis in combination with X-ray fluorescence analysis ...
[60]
What are organic pigments? - SY Chemical Co., Ltd.
(2) Classification by Chemical Structure There are azo pigments, phthalocyanine pigments, polycyclic pigments, triarylmethane pigments and other pigmentsMissing: core | Show results with:core
[61]
Classification of organic pigments
According to the structure classification: (1) azo pigment 59% (2) phthalocyanine pigment 24% (3) triarylmethane pigment 8% (4) special pigment 6% (5) ...Missing: core | Show results with:core
[62]
Organic Pigments - The Chemistry of Art
William Henry Perkins discovered the aniline dyes in 1856. As suggested by the name, these are based on aniline, a benzene molecule with an NH2 group replacing ...Missing: Perkin | Show results with:Perkin
[63]
Pigments for Plastic Colorants: Types, Properties & Processing Guide
Jun 24, 2025 · What are pigments? Pigments are insoluble organic or inorganic particles added to the polymer base to give a specific color to the plastic.
[64]
Pigment Definition & Classification | Baoxu Chemical
Organic pigments can be classified into polycyclic pigments such as azo pigments, phthalocyanine pigments, anthraquinones, indigoids, quinacridones ...Missing: core | Show results with:core
[65]
Dyes and Pigments - ChemicalBook
Based on the chemical composition, it is divided into inorganic and organic pigments ... Chemical Name:Indigo; CAS:482-89-3; MF:C16H10N2O2. Structure: 13765 ...
[66]
Alizarin | C14H8O4 | CID 6293 - PubChem - NIH
Alizarin | C14H8O4 | CID 6293 - structure, chemical names, physical and chemical properties, classification, patents, literature, biological activities, ...
[67]
Anthraquinone dye | Synthesis, Applications, Properties - Britannica
Two natural dyes, alizarin and indigo, have major significance. Alizarin is a red dye extracted from the roots of the madder plant, Rubia tinctorium. Two ...<|separator|>
[68]
https://pubchem.ncbi.nlm.nih.gov/compound/Alizarin
[69]
Organic and Inorganic Pigment Characteristics - Artists Network
Inorganic pigments are heavy with large particles, while organic pigments are lighter with small particles. Inorganic have low tinting strength, organic have ...
[70]
Classifications, properties, recent synthesis and applications of azo ...
Jan 31, 2020 · The azo dyes and pigments are manufactured on an industrial scale by the same reaction sequence in two stages, diazotization and azo coupling. ...
[71]
How Do You Make an Azo Dye? - First Source Worldwide
Mar 7, 2017 · Dye manufacturing consists of five basic steps: diazotization, coupling, isolation-filtration, drying, grinding, and standardization.
[72]
Automotive Paint Pigments: Meeting OEM Standards in 2025
Sep 24, 2025 · High-Performance Organic Pigments. Organic pigments provide the brilliant, clean colors characterizing modern automotive finishes. Premium ...
[73]
Madder lake - ColourLex
The colorants are bound to inorganic substrates such as aluminum hydroxide or calcium carbonate. The chemical stability of all colorants contained in madder ...
[74]
Lake Pigments and Thin-Layer Chromatography of Natural Dyes
Oct 10, 2024 · Lakes are artists' pigments made from colorants bound to an inert substrate, usually hydrated aluminum oxide. Before the late 19th century, ...
[75]
Lake - MFA Cameo - Museum of Fine Arts Boston
Oct 6, 2022 · An organic pigment prepared by precipitation of a dye on a powdered, inorganic substrate. Because of its transparency, Alumina trihydrate, is the most commonly ...
[76]
Natural pigments derived from plants and microorganisms
In this review, we classify pigments into the following categories based on their chemical structures, including flavonoids, carotenoids, pyrroles, quinones, ...
[77]
[PDF] Natural Pigments: Carotenoids, Anthocyanins, and Betalains
Jun 3, 2010 · The natural pigments discussed are Carotenoids, Anthocyanins, and Betalains.
[78]
Anthocyanidins and anthocyanins: colored pigments as food ... - NIH
Anthocyanins are blue, red, or purple pigments found in plants, especially flowers, fruits, and tubers. In acidic condition, anthocyanin appears as red pigment ...
[79]
Natural food pigments and colorants - ScienceDirect.com
The natural color of foods is due primarily to carotenoids, anthocyanins, betanin and chlorophylls, either as inherent food constituents or as food or feed ...
[80]
Natural Melanin: Current Trends, and Future Approaches, with ...
Melanin is a universal natural dark polymeric pigment, arising in microorganisms, animals, and plants. There is a couple of pieces of literature on melanin, ...
[81]
[PDF] Heme‐Derived Bilins - Utah State University
This mini-review attempts to briefly introduce the biological and chemical scope of heme-derived bilins and then focus on currently known bioactive bilins and ...
[82]
A Review of Bacteriochlorophyllides: Chemical Structures ... - MDPI
Bacteriochlorophyllide a (C35H36MgN4O6) was the most abundant bacteriochlorin. It was found in green bacteria, most purple bacteria and Gemmatimonas ...
[83]
(PDF) An Insightful Overview on Microbial Pigment, Prodigiosin
Aug 7, 2025 · Prodigiosin, the bright red pigment produced by organisms of the genus Serratia, is among the more conspicuous pigments extant in the microbial world.
[84]
Natural Colorants: Historical, Processing and Sustainable Prospects
In the past, painters had used natural dyes extracted from plants, insects, molluscs and minerals for their paintings. The unique character of their works were ...
[85]
A review of history, properties, classification, applications and ...
Jul 15, 2024 · This paper presents a comprehensive review on natural and synthetic dyes with particular focus on their history, properties, classification, extraction methods ...
[86]
The biology of color - Science
Aug 4, 2017 · During the 19th century, early evolutionary biologists set out to explain the diversity of colors that they observed as products of natural ...
[87]
Interactions between colour-producing mechanisms and their effects ...
May 22, 2017 · Pigments selectively absorb some wavelengths of light while allowing others to be reflected, and their absorption profile depends on their ...
[88]
Research Features: The Full Palette of Photosynthesis - NASA GISS
The basic purpose of a photosynthetic pigment is to turn light energy into chemical energy, but not all pigments work in the same way. Different pigments ...
[89]
Carotenoids as natural functional pigments - PMC - NIH
Carotenoids are essential pigments in photosynthetic organs along with chlorophylls. Carotenoids also act as photo-protectors, antioxidants, color attractants, ...
[90]
The Retinal Pigment Epithelium - Webvision - NCBI Bookshelf - NIH
Jan 26, 2011 · Pigment epithelial functions are: light absorption, epithelial transport, spatial ion buffering, visual cycle, phagocytosis, secretion and immune modulation.
[91]
The Protective Role of Melanin Against UV Damage in Human Skin
It has been traditionally believed that skin pigmentation is the most important photoprotective factor, since melanin, besides functioning as a broadband UV ...
[92]
[PDF] Vertebrate pigmentation: from underlying genes to adaptive function
Apr 8, 2010 · Structural colors, excluding white, have a base layer of pigment to absorb light and prevent incoherent scattering by the underlying tissue. [29] ...
[93]
Evolutionary Stability of Aposematic Coloration and Prey ...
Species that are unpalatable or otherwise disagreeable to predators have often evolved a coloration consisting of distinct markings and colors that contrast ...
[94]
Vitamin A and Carotenoids - Health Professional Fact Sheet
Mar 10, 2025 · This RDA is also equivalent to 18,000 IU beta-carotene from food or to 36,000 IU alpha-carotene or beta-cryptoxanthin from food. Therefore, a ...
[95]
Regulatory Status of Color Additives - cfsanappsexternal.fda.gov
CAS Reg No or other ID code: 1390-65-4. Color: Carmine. Status: Permanently listed, exempt from certification. Use: Foods, Drugs, Cosmetics.
[96]
Anti-Inflammatory Effects of Curcumin in the Inflammatory Diseases
Nov 2, 2021 · In conclusion, curcumin has good anti-inflammatory properties, and curcumin regulates NF-κB, MAPK, AP-1, JAK/STAT and other signaling pathways, ...
[97]
Golden Rice: Introducing the β-Carotene Biosynthesis Pathway into ...
Golden Rice: Introducing the β-Carotene Biosynthesis Pathway into Rice Endosperm by Genetic Engineering to Defeat Vitamin A Deficiency1. Author links open ...
[98]
Comparative life cycle assessment of astaxanthin production with ...
Greenhouse gas emissions due to energy consumption during the production chain are one of the main issues for microalgae application. For this reason, life ...
[99]
Titanium dioxide - The Essential Chemical Industry
Manufacture of titanium dioxide. There are two main processes, the Sulfate Process and the Chloride Process (Table 1) which use the two principal ores, ilmenite ...
[100]
Complex inorganic pigments - ECHA - European Union
Complex inorganic coloured pigments (CICPs) are typically crystals of mixed metal oxides that are produced by a high temperature calcination process.
[101]
How Proper Milling Techniques Increase Pigment Yield - Hockmeyer
Sep 20, 2023 · The milling process involves the reduction of pigment particle size, breaking down agglomerates, and attaining the desired fineness to enhance ...
[102]
Azo Coupling - Organic Chemistry Portal
Azo coupling is the most widely used industrial reaction in the production of dyes, lakes and pigments. Aromatic diazonium ions acts as electrophiles.
[103]
3 Paint Production Process Challenges (and How to Overcome Them)
Mar 13, 2024 · Specialty dispersion blenders can be equipped to address issues such as temperature sensitivity, high viscosity, pigment reagglomeration, and ...
[104]
Silanes for Filler and Pigment Treatment - Evonik
Silanes bridge organic and inorganic, bonding with fillers/pigments and polymers, improving distribution, adhesion, and water repellency.
[105]
https://www.organic-chemistry.org/namedreactions/azo-coupling.shtm
[106]
QC and product screening of ink and paint with NIRS - Metrohm
Nov 27, 2023 · Quality control (QC) of ink and paint can be done easily during all stages of production with near-infrared (NIR) spectroscopy. Using NIRS for ...
[107]
Some Historical Pigments and their Replacements - Just Paint
Dec 1, 1998 · Vermilion is a toxic pigment made from Mercuric Sulfide. This naturally occurring ore is the source for Mercury, and was ground up as a pigment ...
[108]
Continuous-Flow Synthesis of Pigment Red 146 in a Microreactor ...
Aug 14, 2019 · In this study, a continuous-flow coupling reaction method has been developed for the synthesis of Pigment Red 146 (C.I. PR 146).Missing: manufacturing | Show results with:manufacturing
[109]
Paint Standards and Related Coating Standards - Products & Services
ASTM's paint and related coating standards are instrumental in specifying and evaluating the physical and chemical properties of various paints and coatings ...
[110]
[PDF] tinting strength of pigments
The American Society for Testing Materials has adopted the following definition of tinting strength: "The power of coloring a given quantity of paint or pigment ...Missing: ASTM D1200
[111]
High Opacity in Paint & Coatings: Standard Test Methods
Sep 23, 2025 · Opacity is a film property while hiding power is a property of the whole coating. Hiding power is also known as opacity and contrast ratio. What ...
[112]
ISO Blue Wool No. 6 for Hot Light Fastness
Dec 15, 2023 · Blue Wool No. 6 has been used for decades also for hot light fastness testing but was never really validated for that purpose.
[113]
D279 Standard Test Methods for Bleeding of Pigments - ASTM
Jun 22, 2023 · These test methods cover procedures for determining the bleeding characteristics of dry pigments by direct solvent extraction of the pigment and by ...
[114]
[PDF] dispersibility-of-pigments-and-coatings.pdf - Microtrac
These results show that the mechanical force influences the dispersibility of titanium dioxide particles. Ultrasound probe is the most efficient way to reduce ...
[115]
[PDF] Toxicology and toxicological testing of colorants
The oral acute toxicity. LD50 value of these pigments is greater than 5000 mg/kg. A slight irritation effect of the eyes and the respiratory tract is ...
[116]
Standard Test Method for Oil Absorption of Pigments by Spatula Rub ...
Jun 15, 2021 · This test method covers the determination of the oil absorption of pigments by the spatula rub-out technique.
[117]
Welcome to Colour Index - Colour Index
The unique and definitive classification system for dyes and pigments used globally by manufacturers, researchers and users of dyes and pigments.About Us · CICN · Technical Info · Login / Sign UpMissing: Blue 15 PB15
[118]
The Color of Art Pigment Database: Pigment Blue - PB - Art Is Creation
the Color of Art Pigment Database: Pigment Blue, is a complete artist's reference on blue pigments used in making paint. It includes the Color Index names, ...
[119]
Substances restricted under REACH - ECHA - European Union
The list of substances restricted under REACH will be available in our new chemicals database, ECHA CHEM, since 16 September 2025.
[120]
Color Additives - Information for Consumers - FDA
Sep 17, 2025 · The FDA is responsible for regulating all color additives used in foods, drugs, cosmetics (except for coal- tar hair dyes), and certain medical devices.
[121]
Standard Classification for Dry Pigmentary Titanium Dioxide Products
Jun 16, 2021 · ASTM D476 classifies dry, hiding titanium dioxide pigments for coating applications, grouping them into eight types based on composition, use, ...
[122]
[PDF] ETAD recommended trace metal limits for organic pigments used in ...
ETAD recommends limits for organic pigments: Antimony 250, Arsenic 50, Barium 100, Cadmium 50, Chromium 100, Lead 100, Mercury 25, Selenium 100, Zinc 1000. ...
[123]
https://echa.europa.eu/substances-restricted-under-reach
[124]
Mastering Pantone Colors: Essential Guide for the Packaging Industry
Know Your Substrate: Always consider the substrate you'll be printing on before finalizing a Pantone color. Different materials, such as papers, plastics, and ...
[125]
RAL color systems - RALcolorchart.com
RAL Plastics is the color standard for plastics. The multifunctional plates made of polypropylene ensure the best possible translation of RAL paint color shades ...Missing: molded dispersion
[126]
RAL PLASTICS - RAL USA
RAL PLASTICS is a new color standard especially for plastics, created in response to widespread demand from the plastics-processing industry.Missing: molded dispersion coatings
[127]
Adobe Color: Color palette generator
Design color themes based on color theory with our color palette generator. Use color harmonies on the color wheel to generate beautiful color palettes.Color wheel, a color palette... · Color theme from image · Recolor SVG in Color Lab
[128]
Create and discover unique color themes - Adobe Color
Convert themes into RGB, LAB, CMYK, HSV, and Pantone colors without losing brightness or color accuracy. Download or copy themes in formats that are easy to ...Missing: pigments | Show results with:pigments
[129]
What is Metamerism? | Science Behind Metamarism - X-Rite
May 2, 2016 · Metamerism is a phenomenon that occurs when two colors appear to match under one lighting condition, but not when the light changes.
[130]
[PDF] Color Calculations - iQC - X-Rite
Page 23. Color Calculations. CIE 1976 (L*, a*, b*) color space (CIELAB). CIE L*a*b* (CIELAB) is color space specified by the CIE International Commission on.
[131]
Identifying Color Differences Using L*a*b* or L*C*H* Coordinates
These formulas calculate the difference between two colors to identify inconsistencies and help users control the color of their products more effectively.
[132]
A Nineteenth-Century Book of Color Samples - jstor
A book dated 1809 and containing 276 water-color samples with manuscript notes on their origin, permanence and working properties in oil and water color was ...Missing: swatch 19th Maundler
[133]
Pigments Market Size & Growth Report to 2032
The global pigments market was valued at $27.2 billion in 2022, and is projected to reach $45.4 billion by 2032, growing at a CAGR of 5.3% from 2023 to 2032.
[134]
Titanium Dioxide Market Size, Share, Trends & Industry Forecast ...
Jul 1, 2025 · The Titanium Dioxide Market size is estimated at 360.16 kilotons in 2025, and is expected to reach 440.86 kilotons by 2030, at a CAGR of 4.10% ...
[135]
Europe Pigments Market Size, Share, Trends & Analysis, 2033
The major key players in the Europe Pigments market are EW Nutrition Koninklijke DSM N.V. BASF SE Vidya Europe Production SAS ABBEY COLOR DYNADIS Naturex and ...Market Drivers · Segmental Analysis · Regional Analysis
[136]
Pigments Market - Size, Manufacturers, Industry Share & Growth
Sep 25, 2025 · China accounts for roughly half of regional pigment output and continues to influence global price discovery through its TiO₂ capacity swings ...
[137]
The Post World War II Boom: How America Got Into Gear - History.com
May 14, 2020 · The Post World War II Boom: How America Got Into Gear ... After years of wartime rationing, American consumers were ready to spend money—and ...
[138]
Tariffs and Over-Capacity Reshape TiO2 Market Dynamics
Sep 2, 2025 · Antidumping tariffs and overcapacity are reshaping the titanium dioxide market, with mixed regional outcomes and a slow recovery outlook.
[139]
Global Dyes And Pigments Market Size & Growth Report, 2030
The global dyes and pigments market size was valued at USD 38.2 billion in 2022 and is projected to reach USD 57.8 billion by 2030, growing at a compound ...
[140]
[PDF] TiO2 Forecast: Feedstocks - TiPMC Consulting
Increases in other raw materials, energy prices, logistics, and labor are all common themes for 2022. Cost increases are not just a pigment issue. Smelters ...
[141]
Impact of waste from titanium mining on benthic fauna - ResearchGate
Aug 7, 2025 · 2017. The impacts of mining tailings can also cause immediate fauna burial and chronic effects due to long-term contamination (Olsgard & Hasle ...
[142]
[PDF] AP-42, CH 6.4: Paint And Varnish
Particulate emissions amount to 0.5 to 1.0 percent of the pigment handled. Afterburners can reduce emitted volatile organic compounds (VOC) by 99 percent and.
[143]
Paint: a ubiquitous yet disregarded piece of the microplastics puzzle
Jan 6, 2025 · Recent modeling suggests that paints may be a large source, if not the greatest source, of microplastics to aquatic and terrestrial environments ...
[144]
What Makes a Pigment 'Green'? | Exploring Sustainable Colorants
Apr 18, 2025 · Eco-Friendly Production: Sustainable pigments are made using low-energy, low-water, and solvent-free or low-VOC processes—often in facilities ...
[145]
https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32009L0048
[146]
https://www.researchgate.net/publication/223864518_Impact_of_waste_from_titanium_mining_on_benthic_fauna
[147]
ISO 14040:2006 - Life cycle assessment
ISO 14040:2006 describes the principles and framework for life cycle assessment (LCA) including: definition of the goal and scope of the LCA.
[148]
Using the LCA Method to Develop the Production of Pigment for ...
Aug 8, 2023 · According to the ISO 14,000 standards, the LCA analysis should include four stages: determination of the goal and scope, life cycle inventory ( ...2.4. Recipe 2016 Method · 3. Results · 3.1. Recipe 2016 Method