Daughters of India artisan mixing natural dyes in buckets - orange and white dye liquids being prepared by hand in traditional dyeing workshop

DYEING & COLOUR

THE ART OF
mordanting

Without mordanting, most natural dyes would simply wash away. The mordant is the invisible agent that binds colour to cloth ~ a metallic salt, a mineral, a patient chemical reaction that transforms a fleeting pigment into a lasting part of the fabric. It is both ancient science and living art, and it is the foundation upon which Indian block printing has been built for millennia.

WHAT IS a mordant?

The word "mordant" comes from the French "mordre," meaning to bite. A mordant is a substance that "bites" the dye molecule onto the fibre ~ creating a chemical bridge between the colourant and the cloth that would not form otherwise.

Without this bridge, most natural dyes will not adhere permanently to fabric. They may stain the surface temporarily, but they will wash out, fade rapidly, or bleed onto adjacent fabrics within a few launderings.

Mordants are typically metallic salts ~ compounds in which a metal ion is paired with a non-metallic counterpart. The metal ion is the active agent. It forms a coordination complex with both the dye molecule and the fibre, creating a three-way bond ~ fibre to mordant to dye ~ that is far more stable and wash-resistant than the dye-fibre bond alone.

The concept is simple. The execution is anything but. The type of mordant, its concentration, the temperature and duration of mordanting, the pH of the water, the pre-treatment of the fabric, and the skill of the dyer all influence the final colour. Two dyers using the same dye, the same mordant, and the same fabric can produce different results based on subtle differences in their technique. This is why mordanting is described not merely as a process, but as an art.

Daughters of India artisan pouring natural dye from ceramic vessel into metal tray during traditional textile dyeing process at Indian workshop
Dye paste and mordant mixing tray showing vivid colours ready for block printing
Artisan mixing dye paste colours for block printing

THE PRINCIPAL mordants

Alum ~ Potassium Aluminium Sulphate

Chemical formula: KAl(SO4)2 (often used as the hydrated form, KAl(SO4)2.12H2O)

Effect on colour: Alum is the most commonly used mordant in Indian textile dyeing and has been for thousands of years. It brightens and clarifies colour, producing clear, warm, luminous tones. With madder, alum produces the classic Indian red ~ warm, rich, and enduring. With pomegranate rind, alum gives a clear golden yellow. With lac, alum produces vivid crimson.

Properties: Alum is relatively non-toxic, water-soluble, and widely available. It does not significantly alter the hand (feel) of the fabric. It is the safest and most commonly used mordant across all natural dye traditions worldwide.

In Indian practice: Alum is ground to a paste, mixed with gum arabic or another thickening agent, and applied to the fabric through block printing. The printed mordant paste is invisible or near-invisible on the cloth. When the mordanted fabric is subsequently immersed in a dye bath, only the areas where alum was printed absorb and permanently fix the dye. This is the basis of the entire mordant-printing tradition ~ the ability to produce coloured patterns on white ground using a single dye bath.

Indian name: "Phitkari" (Hindi)

Iron ~ Ferrous Sulphate & Iron Acetate

Chemical forms: Ferrous sulphate (FeSO4), iron acetate (Fe(CH3COO)2 ~ the traditional "kas" or "kasim" made by fermenting iron in jaggery water)

Effect on colour: Iron is a "saddening" mordant ~ it darkens and deepens colour, pulling warm tones toward cool, sombre shades. With madder, iron produces deep purple-black instead of red. With pomegranate rind, iron gives olive green instead of gold. With tannin-rich fabrics (pre-treated with myrobalan), iron alone produces a deep, permanent black.

Properties: Iron is one of the most powerful mordants available. Even in small quantities, it has a dramatic effect on colour. However, iron can weaken cellulose fibres over time ~ the iron ions catalyse the degradation of cotton, a process known as "tendering." This is why iron-printed areas of very old Indian textiles are sometimes the first to deteriorate.

In Indian practice: Iron is the second great mordant of the Indian printing tradition. The classic two-colour Indian block print ~ red and black on white ~ is achieved entirely through the selective application of alum and iron mordants, followed by a single madder dye bath. The alum-printed areas turn red; the iron-printed areas turn black; the unmordanted ground remains white.

Traditional preparation: The traditional "kas" of Rajasthan is made by soaking scrap iron (horseshoe nails, iron filings) in a mixture of jaggery and water for two to three weeks. The organic acids from the fermenting jaggery dissolve the iron, producing iron acetate ~ a dark, pungent liquid that is then filtered and mixed into a printing paste.

TIN, CHROME & beyond

Tin ~ Stannous Chloride (SnCl2)

Effect on colour: Tin is a "brightening" mordant. It produces unusually vivid, luminous colours ~ orange-scarlets with madder, bright clear yellows with pomegranate, and intensely saturated tones with many other natural dyes. The effect is sometimes described as "electric" compared to the warmer tones produced by alum.

Properties: Tin is used sparingly in traditional practice for several reasons. It can damage and weaken fibres, particularly cotton, making the fabric harsh and brittle. It is also more toxic than alum and requires careful handling. Excessive tin mordanting can produce an unnaturally harsh, metallic quality to the colour that skilled dyers consider undesirable.

In practice: Tin is rarely used as a primary mordant in traditional Indian printing. It may be used as a modifier ~ a small addition to the dye bath or a brief after-treatment ~ to brighten specific colours. Some dyers use tin in combination with alum to achieve tones that neither mordant produces alone.

Chrome (potassium dichromate): Produces deep, durable colours with excellent lightfastness. However, hexavalent chromium is toxic and carcinogenic, and its use is increasingly restricted. Most artisan dyers have moved away from chrome, and responsible manufacturers avoid it entirely.

Copper (copper sulphate): Produces green and blue-green tones. Used historically in some Indian dye traditions but less common today due to environmental concerns about copper in wastewater.

Tannins (plant-based): While technically not metallic mordants, tannin-rich plant extracts (myrobalan, pomegranate rind, oak galls, sumac) function as mordants for cellulose fibres. They create binding sites on the fibre that attract and hold both metallic mordants and dye molecules. In the Indian tradition, tannin pre-treatment is the essential first step that makes all subsequent mordanting and dyeing possible.

“In Bagru, a master dyer may test the iron solution by touching a drop to his tongue ~ assessing the concentration by taste. These are not laboratory protocols. They are embodied knowledge.”

The Dyers of Rajasthan

3

Methods of mordanting

4,500+

Years of mordanting history

1

Dye bath ~ multiple colours

THE THREE METHODS OF mordanting

01

Pre-mordanting ~ Before Dyeing

The fabric is treated with the mordant solution before being immersed in the dye bath. This is the most common method in Indian block printing. The mordant paste is printed onto the fabric through hand-carved blocks ~ each block carrying a different mordant paste for a different colour. The fabric is then immersed in a single dye bath, and the printed mordants determine which areas absorb which colours. This method produces the most controlled results and is the foundation of the Indian mordant-printing tradition.

02

Meta-mordanting ~ During Dyeing

The mordant is added directly to the dye bath, so that mordanting and dyeing occur simultaneously. This method is simpler but offers less control over colour placement ~ the entire fabric is mordanted uniformly, producing a single colour across the whole cloth. It is commonly used for solid-colour dyeing rather than patterned printing.

03

Post-mordanting ~ After Dyeing

The fabric is first dyed, and then treated with a mordant to fix and modify the colour. Post-mordanting can be used to deepen or shift colours ~ for example, a fabric dyed with pomegranate rind (yellow) can be post-treated with iron to shift the colour to olive green. This method is particularly useful for colour modification and for improving the fastness of dyes that have poor initial adhesion to the fibre.

Indigo-dyed fabric being revealed from the dye bath, rich blue tones emerging
Artisan pouring indigo dye during the traditional dyeing process
Multi-colour block-printed pattern showing the results of mordant-based dyeing

THE SAAJ PROCESS ~ preparing the cloth

Before any mordanting or printing can take place, the fabric itself must be prepared. In the traditional Indian practice, this preparation is a multi-day process known as "saaj" or "sanana" that transforms raw cotton from a stiff, resistant material into a soft, absorbent ground ready to receive dye.

The traditional saaj process varies by region but typically involves: Desizing ~ removing natural starches and sizing agents with an alkaline soak; Castor oil treatment ~ the fabric is treated with castor oil and goat dung dissolved in water, softening the fibres and improving dye absorption; Soaking and drying ~ repeated cycles of soaking and sun-drying over several days; and Myrobalan treatment ~ soaking in ground myrobalan (harad) to deposit tannins throughout the fibre, creating the chemical foundation for mordant printing.

The entire saaj process can take a week or more. It is patient, unglamorous, repetitive work. But it is essential. A properly prepared cloth will take mordants and dyes cleanly, producing clear, bright colours with good fastness. A poorly prepared cloth will produce muddy, uneven colour that washes out rapidly.

MORDANTING AS science and art

What makes mordanting an art rather than merely a chemical procedure is the number of variables involved and the way experienced dyers navigate them through intuition as much as formula. The concentration of the mordant, the temperature of the water, the pH, the mineral content of the local water supply, the humidity, the fabric's weave density, the specific variety of dye plant, the season in which it was harvested ~ all of these influence the final colour.

In Bagru, a master dyer may test the iron solution by touching a drop to his tongue ~ assessing the concentration by taste. In Sanganer, a printer may adjust his alum paste consistency based on the day's humidity, knowing that the paste will spread differently on a dry winter morning than on a humid monsoon afternoon. These are not laboratory protocols. They are embodied knowledge, carried in the hands and senses of people who have spent decades working with these materials.

This is why the same dye recipe, followed precisely by two different dyers in two different villages, will produce slightly different colours. The water is different. The climate is different. The dyer's hand is different. And this is why every block-printed textile ~ every single one ~ is unique. The mordant's invisible chemistry, shaped by a thousand variables, ensures that no two pieces can ever be exactly the same.

Why This Matters

When you understand mordanting, you understand something fundamental about handmade textiles: colour is not applied like paint. It is grown into the fabric through a complex chemical relationship between fibre, mordant, dye, water, air, and time. This is why handmade colour has a depth and richness that printed synthetic colour cannot match. The colour is not on the surface. It is in the fibre. It is part of the cloth.

THE CLASSIC TWO-COLOUR Indian block print

The classic two-colour Indian block print ~ red and black on white ~ is achieved entirely through the selective application of alum and iron mordants, followed by a single madder dye bath. The alum-printed areas turn red; the iron-printed areas turn black; the unmordanted ground remains white.

This is the elegance of mordant printing: one dye, multiple colours, achieved not by printing different pigments but by printing different mordants that transform the same dye into different hues. It is a system of extraordinary sophistication, developed over thousands of years by artisans who understood chemistry long before the word existed.

Artisan pressing a carved wooden block onto fabric, creating a blue floral print pattern
Indigo dye process showing fabric at an intermediate stage of colour development
The beginning of the indigo dyeing process, preparing the dye vat

Explore Further

THE WORLD OF dyeing & colour

Artisan hand-pouring natural dye onto fabric, warm earth pigment tones emerging in the dyeing process

Madder & Earth Pigments

The dye that demonstrates mordanting most beautifully ~ one root, many colours.
Artisan mixing natural dyes by hand in buckets, orange and white liquid colours showing how hand-mixed dye batches create natural colour variation

Why Colour Varies

And why that variation is beautiful, not a flaw.
Artisan hand-carving intricate patterns into a wooden block for traditional block printing

How Block Printing Works

From fabric preparation to final wash, step by step.
Artisan pouring natural dye from ceramic vessel into metal tray during traditional textile dyeing process

Natural Dyes of India

The extraordinary palette of colour drawn from plants, minerals, and insects.
Explore All Craft Pages
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You can find our full returns policy here.

Shipping & Returns

All prices include VAT and import duties — no hidden fees at delivery. Our slow fashion garments are handcrafted in India and shipped directly to you.

We are a small team however we endeavour to process your order within 1–2 business days. Orders are shipped via DHL Express. You’ll receive a tracking number by email once your order ships.

Delivery Cost
Standard · 5–8 business days 120 kr
Express · 3–5 business days 200 kr
Orders over 2,000 kr Free


All prices include Danish VAT (25%) and any applicable import duties — the price you see at checkout is the price you pay.

You can find our full shipping policy here.

We want you to love your Daughters of India piece. If it’s not quite right, we’re happy to help — simply return within 30 days and we’ll issue a Daughters of India Gift Card for the full value. Your credit never expires and can be used on any piece, including new collections.

  • Items must be returned in original condition — unworn, unwashed with tags attached, folded neatly in the Daughters of India tote bag provided.
  • To lodge a return, visit our Returns Portal. Return shipping is at the customer’s expense — we recommend PostNord for affordable tracked returns.
  • Refunds are processed within 5–7 business days of receiving the return.
  • Final sale items and intimates are not eligible for returns or store credit.

You can find our full returns policy here.

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