Acidic mordants are natural or mineral acids used in dyeing to adjust pH and support the bonding between fibres and colourants. Common acidic sources such as lemon juice, citric acid, and vinegar are especially valued in low-impact dye practices for their accessibility and gentle action on fibres.

Why protein fibres respond better to acidic mordant?

Protein fibres such as wool and silk contain amino groups that readily bond under acidic conditions. Mild acids help open the fibre structure and create ionic bonds with many natural dyes, improving colour uptake and fastness.

• Best suited fibres: wool, silk

• Effect of acid: brighter colours, better penetration, improved fixation

• Traditional practice: acid baths are standard in wool and silk dyeing