Common Natural Dye Terms

DEFINITIONS & ACRONYMS 

(where to find many of supplies noted below cheaply is addressed in my blog post: Inexpensive Natural Dye Supplies.

• Alum/PAS

  • Aluminum Phosphate/Potassium Aluminum Phospate - most effective aluminum mordant for protein fibres. Historically, also used with a tannin for preparing cellulose fibres.

• AA

  • Aluminum Acetate - most effective aluminum mordant for cellulose fibres.

• Adjective or Mordant Dye

  • A natural dye that requires that fibres be mordanted in order to form stable colour results.

• Binder

  • A non-mordant used to physically trap dyes on fibres (rather than molecularly bond them). Usually made from a protein source, such as soya milk.

• CC

  • Calcium Carbonate (chalk). Used as a water hardener, alkali, and precipitant (to fix cellulose mordants, in lake pigment making, and other applications).

• CoT/CofT

  • Cream of tartar - a sediment formed in the winemaking process. Used to soften wool, brighten shades, and point the colour of some dyes – such as the fuchsia of cochineal to a true red. Cream of tartar works best with protein fibres and is seldom used with cellulose fibres.

• Direct or Substantive Dye

  • A natural dye that can form strong molecular bonds with fibres without the use of a mordant. Some dye manuals particularly older ones) sometimes use ‘substantive’ to relate to fastness of dye colour, rather than whether it is a mordant/adjective dye or a direct dye.

• Fe

  • The chemical symbol for iron. The most common iron/ferrous metal salts used for mordanting or modifying fibres (iron ‘saddens’ - i.e. darkens - natural dye results) are ferrous acetate and ferrous sulfate.

• Fugitive

  • A colourant that lacks the molecular structure to form stable bonds with mordants or fibres. Therefore, they are not considered dyes, but instead are referred to as “fugitive”, “fugitive colourants”, “temporary stains”, etc. The red, pink, purple, and blue colour seen in flowers, fruits, and vegetables comes from a class of compounds known as anthocyanins, nearly all of which are highly unstable. They are often used as food colouring, where they can be preserved in oily suspensions, but they can not be used as reliable textile dyes, as they will fade and wash out quickly.

• Metal Salt

  • A compound created when a metal reacts with an acid, releasing hydrogen in the process. Each acid can create many different salts, depending on the metal with which it reacts - a range of acetates from acetic acid, sulfates from sulfuric acid, oxalates from oxalic acid, etc. Metal salts are the most commonly used mordants since antiquity, as they form very stable molecular bonds between natural fibres and natural dyes. Examples include aluminum sulfate, aluminum acetate, ferrous sulfate, and ferrous acetate.

• Modifier

  • Any substance that is used to shift a dye colour. Commonly used modifiers include various acids, alkalis, and iron.

• Mordant

  • A metal salt used to form molecular bridges between fibre and dye. Many hazardous mordants were used in the past (e.g. chrome), but today most natural dyers use relatively benign aluminum and iron metal salts only.

• Tannin

  • A class of astringent compounds widely distributed in the Plant Kingdom, with a strong ability to precipitate many substances. Used to treat cellulose fibres and fabrics before the metal salt mordant. Metal salt mordants do not bond as readily with cellulose fibres as they do with protein fibres. Tannin has a high affinity for cellulose, and precipitates the metal salt into the interior of fibres. For this reason, the order of a tannin-alum mordant combination is very important.

• WOF

  • Weight of Fibre. Mordants and dyes are often calculated as a percentage of the weight of the fibres to be dyed. For example, alum at 7% WOF means that you would weigh your fibres, then calculate 7% of that weight, and use that amount of alum.