Atlas of Natural and Plant-Based Dyes

Every dye listed in this atlas undergoes thorough historical research, grounded in primary sources and recognised academic work. Our documentary base relies on the Colour Index International, the world reference published by the Society of Dyers and Colourists since 1924, which assigns each colourant a unique CI number and catalogues more than 13,000 dyeing substances. This register enables us to trace the evolution of nomenclature and distinguish natural colourants from the historical synthetics that replaced them.

We cross-reference these data with UNESCO Intangible Cultural Heritage lists, which recognise several dyeing traditions: Indonesian batik (inscribed in 2009), Japanese ai-zome indigo (recognised as a living national treasure), Tyrian purple dyeing documented through excavations at Sidon. Ethnobotanical field surveys complete this corpus by documenting local practices still in use, including laterite-based dyes in West Africa, iron gall black in Iran, and madder from the Causses region in France.

Each dye entry is precisely dated. We establish a chronology of use reaching back to the earliest known archaeological evidence: indigo-dyed textile fragments dated to 6,000 years ago found in Peru, madder traces on 3,500-year-old Egyptian fabrics, mentions of saffron on Sumerian cuneiform tablets. This diachronic approach distinguishes dyes with a millennia-old tradition from more recent innovations and measures the continuity of their use in the contemporary textile chain.

Botanical identification of each dye source forms the foundation of our atlas. Every plant, insect or mineral is classified according to Linnaean binomial nomenclature and referenced in the APG IV (Angiosperm Phylogeny Group) databases for plant species. Madder, for example, is identified as Rubia tinctorum L. (Rubiaceae family), to be distinguished from Rubia peregrina which produces different shades. True indigo comes from Indigofera tinctoria, but we also document alternative sources: Isatis tinctoria (woad), Polygonum tinctorium (Japanese indigo) and Strobilanthes cusia (Assam indigo).

Traditional harvesting methods are documented for each source. We describe the optimal harvest calendar (madder requires three years of root growth), the plant parts used (roots, leaves, bark, flowers or fruits) and pre-dyeing preparation techniques (fermentation, drying, grinding). For animal sources such as cochineal (Dactylopius coccus), we detail the farming methods on prickly pear cactus in Mexico and the Canary Islands.

Cultivation requirements are assessed for each dye plant: soil type, rainfall, USDA climate zone, optimal altitude and average colourant yield per hectare. These data allow us to evaluate the potential for relocalising dye crops in Europe and to compare the productivity of different sources for the same chromatic spectrum.

Each natural dye is measured using the CIELAB (L*a*b*) system, an international standard defined by the International Commission on Illumination. This three-dimensional model quantifies lightness (L*, from 0 black to 100 white), the red-green axis (a*, positive = red, negative = green) and the yellow-blue axis (b*, positive = yellow, negative = blue). Each sample is measured three times under D65 illuminant (standard daylight) using a calibrated spectrophotometer, and the mean of three readings is retained as the reference value.

Diffuse reflectance spectrophotometry establishes the complete absorption spectrum of each dye between 380 and 780 nm. This spectrum constitutes a unique fingerprint of the colourant, useful for authenticating a historical dye or detecting the presence of blends. We also measure metamerism, that is, the perceived colour variation under different light sources (D65, A, F11), a critical parameter for the textile industry where fabrics are viewed in-store and then outdoors.

To ensure reproducibility, each colour is matched to a Pantone TCX (Textile Cotton eXtended) reference and its hexadecimal digital equivalent. The delta E (colour distance) between the reference Pantone and the actual measurement is systematically calculated: a delta E below 2 is considered imperceptible, between 2 and 5 perceptible but acceptable, above 5 the batch is recalculated. This precision enables professionals to use our references for production technical specifications.

A dye’s fastness determines its durability under real-world conditions of use. We apply protocols from the ISO 105 standard, the global reference for evaluating dyeing properties. Light fastness is measured according to ISO 105-B02 using the xenon arc test, which simulates solar exposure. Samples are exposed alongside blue wool reference standards and rated on a scale from 1 (very poor) to 8 (exceptional). Indigo typically scores 4-5, madder with alum mordant reaches 5-6, while turmeric rarely exceeds 2-3.

Wash fastness is evaluated according to ISO 105-C06, which simulates a domestic wash cycle at 40 °C with standardised ECE detergent. Samples are rated on a scale from 1 (severe degradation) to 5 (no perceptible change) for staining and colour change. We also test perspiration fastness (ISO 105-E04) in acidic and alkaline media, dry and wet rub fastness (ISO 105-X12) and water fastness (ISO 105-E01). Each dye thus receives a complete fastness profile across six criteria.

Results are presented as a normalised radar chart, enabling visual comparison of each natural dye’s performance against its synthetic equivalent. A natural colourant is deemed viable for ready-to-wear when it achieves a minimum score of 4 in light fastness and 3-4 in wash fastness, which most dyes documented in this atlas reach with appropriate mordanting.

The reactivity of a natural colourant varies considerably depending on the chemical nature of the textile fibre. Protein fibres (silk and wool) possess amino and carboxyl groups that form ionic and hydrogen bonds with many colourants, offering high natural affinity. Silk, in particular, absorbs dyes with remarkable intensity thanks to its fibroin structure and large specific surface area. Wool, with its keratin scales, retains colourant within its internal structure through a temperature-controlled diffusion mechanism.

Cellulose fibres (cotton, linen, hemp, ramie) show lower affinity with most natural colourants due to their negative surface charge. The use of a mordant then becomes indispensable. Alum (double sulphate of aluminium and potassium) remains the most widely used mordant: it forms a metal complex between colourant and fibre, improving both fixation and fastness. Iron (II) sulphate shifts the hue towards darker, cooler tones. Tannic mordants (gallnut, sumac) are preferred for cellulose fibres because they create an initial bonding bridge before the main colourant.

Each entry in our atlas presents a compatibility matrix tested on four reference substrates: 19-momme charmeuse silk, 18.5-micron merino wool, combed Pima cotton and Normandy linen. Each combination is evaluated with and without mordant, allowing direct comparison of the mordanting impact on intensity (CIELAB measurement) and fastness (ISO scale). This systematic approach covers more than 200 colourant-fibre-mordant combinations catalogued in the atlas.

Each natural dye in our atlas undergoes a multi-criteria environmental assessment. Toxicity is evaluated against the ZDHC (Zero Discharge of Hazardous Chemicals) framework, an industry initiative bringing together more than 170 textile brands committed to eliminating hazardous chemicals. We classify each dyeing substance according to the ZDHC MRSL (Manufacturing Restricted Substances List): the vast majority of referenced natural dyes are in full compliance, unlike many synthetic azo colourants that appear on REACH ban lists.

Biodegradability is assessed according to OECD 301 (ready biodegradability) and 302 (inherent biodegradability) standards. Natural dye effluents typically degrade by more than 90% within 28 days, compared to 40 to 70% for synthetic reactive colourants. Water consumption is measured in litres per kilogram of dyed fabric: indigo dyeing by fermentation uses approximately 30 litres per kilogram, compared to 100 to 150 litres for synthetic dyeing with multiple rinses.

For each dye, we establish a comparison with the synthetic equivalent across five axes: carbon footprint (kg CO2 eq.), water consumption, aquatic toxicity (EC50), biodegradability and regulatory compliance. This comparison enables professionals to objectively assess the real environmental benefit of switching to natural, avoiding the greenwashing trap of assuming a colourant is ecological simply because it is plant-derived.

Field expertise forms an essential pillar of our atlas. We collaborate with master dyers from centuries-old traditions in four reference countries. In Japan, ai-zome artisans from Tokushima have perpetuated since the twelfth century the art of indigo dyeing by alkaline vat fermentation (sukumo), a technique producing a deep blue that is irreproducible by synthetic means. Each living vat is a bacterial ecosystem that the dyer tends daily, adjusting temperature, pH and feeding.

In India, ajrakh artisans from Gujarat practise a resist-printing technique using mud and plant dyes whose origin traces back to the Indus Valley civilisation (3300-1300 BCE). The complete process comprises sixteen steps of washing, mordanting, printing and dyeing, spread over two weeks. In France, the Pastel de Lectoure workshop in the Gers department has revived the cultivation and processing of Isatis tinctoria, producing a 100% French pastel blue pigment used in both textile dyeing and cosmetics.

In Morocco, traditional dyers from Fez and Marrakech use saffron (Crocus sativus) for luminous yellows and pomegranate (Punica granatum) for golden beiges. Each artisan we consult contributes a detailed technical sheet listing their recipes, bath times, temperatures and vat tips passed down orally from generation to generation. This empirical knowledge, cross-referenced with our scientific measurements, considerably enriches the precision of our atlas entries and helps preserve intangible heritage at risk of disappearing.

A natural dye is a colourant extracted from biological sources without synthetic chemical transformation. The three main families are plant colourants (extracted from roots, leaves, bark, flowers or fruits), animal colourants (cochineal, murex purple, kermes) and mineral colourants (ochres, earths). The fundamental distinction from a synthetic colourant lies in the manufacturing process: a natural colourant is obtained by extraction (maceration, decoction, fermentation) from a biological raw material, whereas a synthetic colourant is assembled molecule by molecule in a laboratory from petrochemical precursors.

The first laboratory synthesis of a colourant dates to 1856, when William Henry Perkin accidentally produced mauveine from aniline. Before that date, the entire world textile production relied exclusively on natural dyes. Today, synthetic colourants account for more than 99% of the global textile dye market, but a return to natural has been accelerating since the 2010s, driven by environmental concerns and consumer demand for traceability. The Colour Index International lists approximately 500 identified natural colourants, compared with more than 10,000 synthetic references.

The fastness of natural dyes depends on the colourant, the fibre and the mordant used. Indigo, for example, achieves a light fastness of 4 to 5 on the ISO 105-B02 scale (1 to 8) and a wash fastness of 4 to 5 on the ISO 105-C06 scale (1 to 5), scores comparable to many synthetic reactive colourants. Madder (Rubia tinctorum), with an alum mordant, reaches 5 to 6 in light fastness, which is excellent. Turmeric and safflower, however, show light fastness below 3, making them unsuitable for intensive clothing use.

Mordanting is the key to natural dye fastness. A metallic mordant (alum, iron, tin) forms a chemical complex between colourant and fibre that significantly improves resistance to washing and light. Protein fibres (silk, wool) naturally show better affinity with colourants, offering superior fastness without mordant compared to cellulose fibres. With appropriate mordanting and a relevant colourant choice, natural dyes achieve performance sufficient for ready-to-wear, even though some latest-generation synthetic colourants remain unbeatable on extreme fastness ratings.

A mordant (from the Latin mordere, to bite) is a chemical substance that acts as an intermediary between the colourant and the textile fibre. Without a mordant, most natural colourants only adhere superficially to the fibre and wash out in the first laundry cycle. The mordant forms a tridentate metal complex with colourant molecules on one side and the functional groups of the fibre on the other, creating a stable chemical bridge. Alum (aluminium potassium double sulphate, KAl(SO4)2) is the oldest and most widely used mordant: it is non-toxic, does not alter the hue and delivers excellent fastness.

Iron (II) sulphate, or green vitriol, is a mordant that darkens and cools shades, producing greys, olive greens and deep blacks. Vegetable tannins (gallnut, oak bark, sumac) serve as pre-mordants on cellulose fibres: they create a bonding layer rich in hydroxyl groups that improves subsequent colourant fixation. The tannin + alum combination is the historical reference method for dyeing cotton and linen with natural colourants. Mordanting typically accounts for 30 to 40% of the total natural dyeing process time, but it is essential for achieving durable and reproducible colours.

Indigo is unquestionably the most widespread natural colourant in human history, used independently on every continent for millennia. Indigo-dyed textile fragments dated to 6,000 years ago were found at Huaca Prieta in Peru, making indigo the oldest identified textile colourant. It is produced by more than 700 different plant species, the main ones being Indigofera tinctoria (India), Isatis tinctoria (Europe, woad), Polygonum tinctorium (Japan) and Strobilanthes cusia (South-East Asia).

The indigotin molecule (C16H10N2O2) is identical regardless of the plant source, which explains the worldwide convergence of its use. Its dyeing process is unique: indigo is insoluble in water and must be reduced to leuco-indigo (soluble form) in an alkaline medium to penetrate the fibre. On contact with air, it reoxidises and regains its blue colour, fixed within the fibre through a physical crystallisation mechanism. This particular chemistry explains why indigo requires no mordant and produces that unique deep blue that darkens with washing rather than fading, a phenomenon that denim has made famous worldwide.

Recognising a naturally dyed garment requires attention to visual and tactile cues. Natural dyes generally produce more nuanced and less uniform colours than synthetics: subtle hue variations (called abrash in the rug world) are normal and attest to the authenticity of the process. Natural colours possess an optical depth that synthetics struggle to reproduce: a natural indigo shows coppery reflections in raking light that synthetic indigo does not.

Labelling is the first reliable indicator. GOTS (Global Organic Textile Standard) and Naturtextil IVN certifications require colourants to be of natural origin and verify compliance through laboratory analyses. In the absence of certification, the manufacturer’s transparency about their dyeing supply chain is a positive signal. Some brands mention the source plant on the label (indigo, madder, walnut) and provide specific washing instructions adapted to natural colourants. A simple test exists: rub the fabric with a damp white cloth. Natural dyes, particularly indigo, tend to release a slight pigment transfer, a normal phenomenon called crocking that does not occur with solidly fixed synthetics.

Raspoznavaniye odezhdy, okrashennoy naturalnym krasitelem, trebuyet vnimaniya k vizualnym i taktilnym priznakom. Naturalnyye krasiteli obychno proizvoduat boleye niuansirovannyye i meneye odnorodnyye tsveta po sravneniyu s sinteticheskimi: tonkiye variatsii ottenka (nazyvayemyye abrash v mire kovrov) yavlyayutsya normalnymi i svidetelstvuyut ob autentichnosti protsessa. Naturalnyye tsveta obladayut opticheskoy glubinoy, kotoruyu sintetika s trudom vosproizvodit: naturalnoye indigo pokazyvayet mednyye otblesky v skolzyashchem svete, kotorykh sinteticheskoye indigo ne dayot.

No, and this nuance is essential to avoid greenwashing. A natural dye is not automatically ecological. Three factors determine its real environmental footprint. First, the mordant: alum is relatively harmless, but chrome sulphate (chrome mordant), historically used for wool, is a CMR-classified pollutant (carcinogenic, mutagenic, reprotoxic) whose use is now banned under REACH. Tin and copper mordants also raise aquatic toxicity concerns at high concentrations.

Second, resource consumption: some natural dyes require enormous quantities of raw material. Cochineal carmine needs 70,000 insects to produce 500 grams of colourant. Saffron requires 150,000 flowers for one kilogram of stigmas. Overexploitation of certain dye plants can threaten local biodiversity. Third, effluents: even natural dye baths discharged into the environment without treatment represent a high organic load (BOD, COD) that can cause eutrophication of waterways. The responsible approach is to evaluate each dye individually across its entire life cycle, without presuming it to be harmless simply because it is plant-derived.

Cochineal (Dactylopius coccus) produces the most intense red in the natural world thanks to carminic acid (C22H20O13), which represents 19 to 24% of the dry weight of the female insect. This anthraquinone molecule absorbs light in the 480-560 nm region (green-yellow), reflecting a crimson red of exceptional chromatic purity. Carminic acid complexed with aluminium forms carmine (aluminium lake), a pigment used since the Aztecs that fetched prices equivalent to gold in sixteenth-century Europe.

Cochineal is also the only natural red colourant authorised in food (E120) and cosmetics (CI 75470) in Europe, as its oral toxicity is virtually nil. Its light fastness reaches 5-6 on the ISO scale, superior to madder and safflower. In Peru and Mexico, cochineal farming on prickly pear cactus (Opuntia ficus-indica) produces approximately 500 tonnes per year, 85% of which goes to the food industry. Textiles absorb only about 5% of world production, but this demand is growing steadily, driven by brands committed to high-end natural dyeing.

Misciano integrates natural dyes within a selective and transparent approach. Our colour palette is designed prioritising colourants whose fastness has been verified on our preferred fibres: silk, merino wool, cashmere and premium cotton. Natural indigo is used for our deep blues, madder with alum mordant for reds, gallnut combined with iron sulphate for blacks and greys, and weld (Reseda luteola) for luminous yellows. Each dye supplier is selected based on botanical traceability, ZDHC compliance and colourimetric reproducibility criteria.

We do not claim a 100% natural palette: some shades still require Oeko-Tex certified colourants when no natural alternative achieves the fastness required for daily wear. This transparency is intentional: we believe it is better to use 60% rigorously selected natural dyes than to claim 100% while sacrificing quality or using polluting mordants. Each naturally dyed piece carries a specific label mention indicating the source colourant and mordant used, in accordance with Naturtextil IVN requirements.

The colouring molecule is identical: indigotin (C16H10N2O2) produced by woad (Isatis tinctoria) is chemically indistinguishable from that produced by tropical indigo (Indigofera tinctoria). However, woad contains approximately 0.2 to 0.5% indigotin by dry leaf weight, compared with 2 to 4% for tropical indigo. It therefore takes roughly ten times more plant material to obtain the same quantity of colourant, making woad economically more expensive to produce.

Historically, the woad trade made the fortune of the Pays de Cocagne region (Toulouse-Albi-Carcassonne triangle) between the thirteenth and sixteenth centuries, before tropical indigo imported from India supplanted it permanently. Today, initiatives such as Pastel de Lectoure in the Gers have revived Isatis tinctoria cultivation in France, producing a certified French-origin pastel blue pigment. The shades obtained differ slightly from tropical indigo due to secondary compounds (isatin, indirubin) that give woad a slightly more violet tonality and brighter reflections, valued in high-end artisan dyeing.

Protein fibres, particularly silk and wool, show the best affinity with natural colourants. Silk is the ideal fibre: its fibroin structure offers a very high specific surface area and numerous accessible amino groups, enabling dense colourant fixation without prior mordanting for many dyes. Merino wool also absorbs dyes efficiently thanks to its keratin scales that retain colourant within its internal matrix.

Cellulose fibres (cotton, linen, hemp) dye less well without mordant, as their negative surface charge repels colourant molecules. With a tannic pre-treatment followed by alum mordanting, cotton achieves satisfactory colour intensities but generally 20 to 30% lower than those obtained on silk under the same conditions. Linen has a more rigid tubular structure that complicates colourant penetration but produces shades of remarkable luminosity once the process is mastered. Synthetic fibres (polyester, nylon) do not dye at all with natural colourants without prior chemical surface modification.

Tyrian purple, the most precious colourant of antiquity, still exists in experimental form but is no longer produced on an industrial scale. This colourant was extracted from the hypobranchial mucus of marine molluscs, principally Bolinus brandaris and Hexaplex trunculus, Mediterranean murex snails. Approximately 12,000 molluscs were needed to obtain 1.5 grams of pure colourant, which explained its astronomical price: in the fourth century, a pound of purple silk cost the equivalent of 150,000 euros today.

The active molecule is 6,6-dibromoindigo, a brominated derivative of indigotin. A handful of university laboratories and passionate artisans continue to produce Tyrian purple in small quantities for research or artistic experimentation. In Tunisia and Lebanon, archaeologists have reconstructed the ancient vats of Sidon and Carthage to understand production processes. The molecule has been synthesised in the laboratory, but its cost remains prohibitive for any textile application. Tyrian purple thus remains a fascinating object of historical and scientific study, witness to a lost craft that linked chemistry, marine biology and political power in ancient Mediterranean civilisation.

Caring for a naturally dyed garment rests on four fundamental principles. First, wash cold or at 30 °C maximum with a mild neutral pH detergent (pH 7), without optical brightening agents or sodium percarbonate. Alkaline detergents (pH above 9) degrade certain sensitive natural colourants, particularly cochineal and flavonoid-based dyes. Second, dry in the shade and never in direct sunlight: prolonged UV exposure is the primary degradation factor for natural dyes.

Third, wash inside out to reduce mechanical abrasion on the visible face. Rubbing is particularly damaging to indigo dyes, whose surface crystallisation fixation mechanism makes the pigment vulnerable to mechanical forces. Fourth, avoid dry cleaning with perchloroethylene for indigo or cochineal-dyed pieces: prefer CO2 cleaning or professional wet cleaning. By following these simple precautions, a naturally dyed garment retains its colours for many years, even developing a unique patina over time that constitutes one of the recognised charms of plant-based dyes.