Mordants (Fixing Colour) – The Secret of Color Bonding

The Concept Dipping clothing in dye will cause it to wash out. To chemically bond the dye to the fabric, a ‘biter’ (mordant) is required. Alum is the most popular mordant.

The Story Roman historian Pliny the Elder once marveled at Indian garments that could be washed repeatedly without losing their vivid color. The secret was a “biter” called a mordant—metallic salts like alum (Saurashtri) that chemically bond dye to fabric. While others simply dipped cloth in pigment, Indian dyers understood the molecular bridge between fiber and color. This mastery of chemical bonding made Indian textiles so popular that 17th-century England actually banned them to protect their own industries.

The Timeline

The Original Text

Sanskrit Shloka: रागाः सर्वे ससौराष्त्र्याः भवन्ति द्युतिमत्तमाः । तस्मात् सौराष्ट्रिकां युञ्ज्यात् रङ्गबन्धाय वाससाम् ॥

Transliteration: Rāgāḥ sarve sasaurāṣtryāḥ bhavanti dyutimattamāḥ | Tasmāt saurāṣṭrikāṃ yuñjyāt raṅgabandhāya vāsasām || Amarakosha (Lists types of alum and red Earths) .

Meaning: “All dyes mixed with Alum (Saurashtri) become most brilliant. Therefore, one should use Alum for the binding of color (Rangabandha) to the clothes.”

 

Related Innovations The Brihat Samhita (about 550 CE) and the Atharva Veda mention ‘colour binders’ (Rangabandhana) such as Lodhra bark and Alum (Saurashtri). They explain why these mordants are necessary to make vegetable dyes persistent on cotton fibres.

Fun Fact France and England restricted printed cotton textiles from India (Chintz) in the 17th century due to their popularity in Europe. They wished to defend their own wool enterprises.

The Modern Legacy Understanding chemical bonding is crucial to the polymer and plastics industries.