Acid dye

Description

A large class of dyes containing one or more acidic end groups (sulfonic, phenolic, carboxylic, etc.) that react with the basic end groups found in amides (silk, wool, leather, and nylon) to form a uniform, lightfast color. Acid dyes are rarely used on cotton or linen. These dyes are soluble in weak solutions of acetic, citric, formic, or sulfuric acids. Many acid dyes are also used to food coloring and histological staining.

Most acid dyes have one of the following type of structures:

• Anthraquinone: Many acid dyes are synthesized from anthraquinone and tend to be blue in color.
• Azo: Most azo dyes are not acid dyes, but the acid dyes of the azo type are red in color.
• Triphenylmethane: Acid dyes formed from triarylmethane are usually yellow or green.

Acid dyes can also be separated into classifications based on their properties.

• Leveling acid dyes: low molecular weight dyes that tend to have low washfastness; require an acid bath (pH 2-4) for application.
• Milling dyes: high molecular weights that usually have exhibit good washfastness; may be applied in a more neutral pH bath (pH 4-7).
• Metal complex acid dyes: dyes complexed with a metal ion like chromium or cobalt; may be applied over a larger range (pH 2-7).

See also Dye types.

Synonyms and Related Terms

anionic dye; colorante ácido (Esp.); colorant acide (Fr.); colorante acido (It.); corante ácido (Port.)

Commercial brands: Jacquard Acid Dyes; PRO WashFast Acid Dyes; Dharma Acid Dyes

Risks

• Some acid dyes are mutagenic and carcinogenic

Physical and Chemical Properties

• Soluble in acidic solutions.

Resources and Citations

• Wikipedia: Acid dye Accessed May 2026
• G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 284
• Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993
• Hoechst Celanese Corporation, Dictionary of Fiber & Textile Technology (older version called Man-made Fiber and Textile Dictionary, 1965), Hoechst Celanese Corporation, Charlotte NC, 1990
• Rosalie Rosso King, Textile Identification, Conservation, and Preservation, Noyes Publications, Park Ridge, NJ, 1985
• Matt Roberts, Don Etherington, Bookbinding and the Conservation of Books: a Dictionary of Descriptive Terminology, U.S. Government Printing Office, Washington DC, 1982
• Van Nostrand's Scientific Encyclopedia, Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976
• Fairchild's Dictionary of Textiles, Phyllis G.Tortora, Robert S. Merkel (eds.), Fairchild Publications, New York City, 7th edition, 1996
• Thomas B. Brill, Light Its Interaction with Art and Antiquities, Plenum Press, New York City, 1980