What is An Acid Dye | Overview

Acid dyes are a type of synthetic dye. These are used for dyeing various polymer clays and surfaces. These dyes are anionic, can be dissolved in water, and are mainly applied from an acidic bath. They have the composition of acidic groups like SO3H and COOH. They are used to add color to several fabrics like wool, silk, and nylon. The electrolyte is added to the higher concentration to form the leveled shades of these dyes. These are usually used for dyeing fabrics with low pH. These are widely used in the food and medical industries.

Features of the Acid Dye

  • Overall wash fastness of acidic dyes is poor, but the light fastness is great.

  • They possess a stronger binding ability to various materials.

  • These dyes are ionic in nature and are soluble in water.

  • The major acids present in the acid dyes are sulphuric, acetic, or formic, which makes them pH neutral and facilitates their application.

  • These aren’t suitable for cellulose and do not work well with cotton. But these work wonders on silk and nylon, which shows that they have substantivity towards protein and polyamide fibers.

This dyestuff, when used with a reducing agent, generally decolorizes, and several craftsmen use this to add different shades to the product and alter the colors of the polymers.

Acid dyes are generally classified based on their wet fastness and dyeing ability.

Different Types of Acid Dyes are

Leveling Acid Dyes

These dyes have low wet fastness and are not suitable for fabrics. They possess the highest level of dyeing properties. Leveling dyes usually have smaller molecules.

Fast Acid Dyes

These are also known as perspiration-fast dyes. Fast acid dyes are mono-sulfated and have high wet fastness. They are best for hard-to-dye protein fibers like wool.

Milling Acid dyes

Some milling acid dyes have low light fastness and are not combinable. These are generally used as Selfshades only.

Metal complex acid dyes

These are the recent chemically synthesized dyes. They use different metals to alter the properties of the dyes and make them suitable for different uses. Metal complex acid dyes are the most economical dyes and are used in various industries. They provide a wide range of colors and shades. They have high light fastness and also the best-wet fastness.


All the acid dyes have excellent dyeing properties, due to which they are used to add color to various hard-to-dye fabrics. These are the best dyes for coloring heavy carpets and yarn in the hank form. These dyes also play a major role in coloring interior textiles and pieces of wood.

Super milling acid dyes generally add bright colors to silver and yarns. Acidic dyes also play a significant role in the food industry. They are used to make the food more attractive and appealing. Several beverages and drinks have these dyes. Azo dyes are the most common example of acidic(edible) dyes that are used in frosting, making cookies, bread, and candies.

With advancements in technology, a wide variety of edible acid dyes are available. Do check out these acid dyes if you want to color the natural fibers or make your food attractive.

Also read,

What is Dyes: Different Types Of Dyes

What Are Pigment Dyes? A Comprehensive Guide

What’s the Difference Between Dyes and Pigments? A Complete Overview

What is Reactive Dye in Printing, Fabric and Chemistry?