Natural Dyeing and Printing Glossary

all the terms you ever needed to know.

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Glossary of Important Terms in Natural Dyeing (Alphabetical Order)

Acid Modifier A substance (e.g. vinegar, citric acid) used to lower the pH of a dye bath, often shifting color hues toward redder tones.

Afterbath A treatment applied to dyed fibers to modify color or improve fastness, often with pH changes or metal salts.

Alkaline Modifier A substance (e.g. soda ash, ammonia) used to raise the pH of the dye bath, influencing color outcome.

Alum Potassium aluminum sulfate, a common mordant for both protein and cellulose fibers. Abbreviation: KAl(SO₄)₂·12H₂O

Aluminum Acetate A mordant often used on cellulose fibers for brighter, clearer colors than alum alone.

Aluminum Lactate A mild organic aluminum mordant derived from lactic acid, used as an eco-friendlier option for cellulose.

Aluminum Sulfate A form of alum that is less acidic than potassium alum, often used interchangeably.

Aluminum Triformate (ATF) A modern aluminum-based mordant known for low toxicity and suitability for most fibers. Abbreviation: ATF

Assist Any additive that helps the dyeing process, such as pH modifiers, thickeners, dispersants, or humectants.

Batch Dyeing Dyeing done in a static or standing dye bath, as opposed to continuous or flow systems.

Bloom The light surface sheen or silvery coating that can appear on indigo-dyed fabrics, from indigotin crystallization.

Boiling A high-heat process in which fabric or dye material is brought to a full, rolling boil (100°C), sometimes used for extraction or scouring.

Botanical Printing The technique of printing plant matter onto fabric using heat, pressure, and mordants; also known as eco-printing.

Bundling Wrapping or rolling fabric with plant material for botanical printing; often followed by steaming or simmering.

Calx An old term for lime (calcium hydroxide), used to raise pH in indigo vats. Abbreviation: Ca(OH)₂

Cellulose Fibers Plant-derived fibers like cotton, linen, hemp, which generally need mordants to retain dyes effectively.

Colorfastness The durability of a color on fabric, indicating resistance to fading from light, washing, or rubbing.

Copper Acetate A copper-based mordant and modifier that may give slightly different color effects than copper sulfate.

Copper Sulfate A metal salt used as a mordant or modifier, which shifts color and enhances fastness. Abbreviation: CuSO₄

Crocking The unwanted transfer of dye from fabric to skin or other materials, due to poor fixation.

Discharge The process of removing color from dyed fabric, often to create patterns using acidic or reducing agents.

Dye Bath A prepared solution of dye, water, and any necessary modifiers or mordants in which fiber is submerged for coloring.

Dye Lake A pigment created by precipitating dye onto a base such as alumina; used more in paint than on textiles.

Dye Stuff Any raw material (excluding specific examples here) used to extract dye.

Enteric Fermentation Vat A traditional indigo vat that uses manure and fermentation to reduce indigo to its soluble form.

Extract A concentrated, usually water-soluble form of dye matter, made from raw plant or insect materials.

Fermentation Vat An indigo dyeing vat that uses organic matter (bran, fruit, etc.) to reduce indigo without chemicals.

Ferrous Acetate A mildly acidic iron-based mordant sometimes prepared at home using iron and vinegar.

Ferrous Sulfate An iron salt used as a mordant or modifier to sadden colors and deepen tones. Abbreviation: FeSO₄

Fixative Any substance (often a mordant) that helps affix dye to fibers.

Fugitive Dye A dye that fades rapidly when exposed to light or washing, due to poor fastness.

Gallnut / Oak Gall A tannin-rich growth on oak trees used as a mordant or mordant assist (not classified here as a dye).

Green Extraction A sustainable method of dye extraction using minimal water and no toxic chemicals.

Indigotin The active blue pigment in indigo-producing plants; insoluble in water but soluble when reduced. Abbreviation: C₁₆H₁₀N₂O₂

Lake Pigment See “Dye Lake”.

Lightfastness A dye or pigment’s resistance to fading under exposure to sunlight.

Lime See “Calx”.

Modifier A substance added to change or enhance a dye's final color (e.g. iron to darken, copper to shift tone).

Mordant A binding agent, typically a metal salt, that creates a bond between fiber and dye. Includes alum, aluminum acetate, aluminum triformate, aluminum lactate, iron (ferrous sulfate, ferrous acetate), copper sulfate, copper acetate, and tin chloride.

Mordanting The process of applying a mordant to fiber before or during dyeing.

pH Modifier Any substance used to adjust the pH of a dye bath. Acids lower pH, alkalis raise it.

Post-mordanting Applying a mordant to fiber after dyeing, often used to shift color or improve fastness.

Precipitation A chemical reaction in which dissolved substances form a solid, often used to create lake pigments by combining dye with a mordant base.

Pre-mordanting Applying mordant to fiber before dyeing.

Pre-wetting Soaking dry fiber in plain water before dyeing or mordanting to ensure even dye penetration and prevent blotching.

Protein Fibers Animal-based fibers such as wool, silk, alpaca, and mohair, which naturally bond well with dyes.

Reduction A process in indigo dyeing where the dye is chemically altered to become soluble.

Scouring The deep cleaning of fibers before dyeing to remove oils, waxes, and dirt that prevent dye uptake.

Shading Using secondary (leftover) dye baths to subtly shift a dye color, sometimes also refers to post mordant baths with ferrous sulfate or alum.

Simmering A gentle heating process just below boiling (around 85–95°C), used for extracting dyes or mordanting without damaging delicate fibers.

Soda Ash Sodium carbonate, a pH-raising substance used in scouring and dye baths. Abbreviation: Na₂CO₃

Solution A homogeneous mixture composed of a solute (e.g. dye or mordant) dissolved in a solvent (usually water).

Steaming A method of heat application (often for botanical prints or setting color) where fabric is exposed to hot steam rather than submerged in liquid.

Steeping Allowing fiber, dye material, or mordanted cloth to soak in a liquid (often at warm or room temperature) to extract color or assist absorption.

Substantive Dyeing Dyeing without a mordant, relying on a dye’s ability to bind directly to fiber.

Tannin A naturally occurring polyphenol used as a mordant or assist, especially important for cellulose fibers.

Tin Mordant Usually tin(II) chloride, used to brighten colors but considered toxic and less eco-friendly. Abbreviation: SnCl₂

Turkey Red Process A historical multi-step method of dyeing cotton using oil, alum, and alkaline treatments to produce red.

Vat Dye A dye that requires a reduction process to be soluble, such as indigo. Dyeing occurs in reduced state, then oxidized on the fiber.

Weight of Fiber (WOF) The dry weight of the fiber being dyed; used to calculate amounts of dyes and mordants.