natural dyes are both science and magic. while there are many factors that go into what makes a final colour result and a level of unpredictability that you have to be comfortable with as a result, there is a scientific basis that we know now with natural dyes that can help us to troubleshoot and have reasonably reliable expectations for our dye results. the basics of these are outlined below - keep in mind that these are still best applied as a general guideline rather than something set in stone.

here are some basic glossary terms that will help you as you continue learning about natural dyes:

cellulose fibre - plant-based fibres comprised of beta-glucose chains. common fibres include cotton, linen, hemp, bamboo, and ramie, and can also include regenerated fibres created through the viscose or lyocell methods, including viscose rayon, lyocell, and tencel. due to the large amount of environmentally damaging chemicals that are not recycled and energy waste involved in processing viscose rayon and bamboo textiles, it is generally recommended that natural dyers stick to secondhand sources of these fibres.
mordant - refers to both the mordant agent and act of mordanting. mordants are metal salts (i.e. alum, iron, copper) that create a chemical bond between natural dyes and fibres. the majority of natural dyes require the use of a mordant to adhere properly to textiles. cellulose fibres require the addition of tannins to the mordanting process to create the correct chemical conditions to allow dye to adhere.
natural dyes - typically the term used to refer to source materials of dyes occurring in the natural world (i.e. not synthetically created). natural dyes can be sourced from a variety of plants, lichens, mosses, fungi, mollusks, and insects. natural dyes are typically named after their source, for example cochineal comes from cochineal insects and madder comes from the madder plant’s root. however, the sources themselves are not the actual dyes. they contain a variety of chemicals from any of the following chemical groups: anthraquinoids (most of the red dyes), napthoquinoids (henna and walnut), flavonoids (most of the yellow dyes), indigoids (indigo and mollusk purple), and tannins (split further into gallotannins and condensed tannins). there is also then further distinction between dyes (soluble in water) vs. pigments (not soluble in water, requires a binding agent to adhere to the fibre and can alter the surface of the textile). further than that, dyes are categorized into three major dye classes: dyes applied directly without mordants, mordant dyes, and vat dyes. for the purpose of keeping things simple here, natural dye means the naturally-occurring materials used to dye other natural materials (wool, cotton, linen, bones, wood, leather, etc.).
protein fibre - animal-based fibres comprised of amino acids. common fibres include wool, silk, leather, and hair. note that the increase of use of “ahimsa” or “peace” silk, purported to be more humane than traditional silkworm processing, is not actually kinder and is also more resource-intensive. traditional silkworms are dissolved in their cocoons in the process of collecting the silk fibres, whereas ahimsa silk allows the silkworms to hatch, creating a hole (and therefore breaks) in the silk. however, due to centuries of cultivation and evolution, silkworms are unable to live beyond a few hours, and the breakages in ahimsa silk fibres requires significantly more silkworms to be processed to create the same amount of textile.
scour - cleaning the fibre prior to dyeing to remove any oils, waxes, or other contaminants that can affect the ability of dye to penetrate fully.

there are multiple steps that must be taken when we are working with natural dyes. depending on the dye, some of these steps look different (for example, vat dyes do not require mordants or tannins, and dyes that are classified under the “mordant dyes” umbrella contain their own necessary mordants for reliable adhesion), but for the vast majority of natural dyes, these are the basic steps:

scour your fibre (the scouring agent and method will vary depending on your fibre).
apply tannin (cellulose fibres only).
apply mordant (protein and cellulose fibres).
dye your fibres.
rinse thoroughly.

when we are dyeing protein fibres versus cellulose fibres, we need to make some adjustments to how we work with our fibres so that they set properly. if we think of things at the molecular level as a puzzle that needs all of its pieces to come together, the following graphics (which also work as identifying the different steps we need to take for dyeing our fibres) show how each of these processes generally* work:

*in part 2 of the basics next week, we will be going over some of the nuances of working with natural dyes, including the differences between mordants and binders/assists and how the application of each can impact your dye results.

this post is part of a larger series on the basics and care for natural dyes. they’re not designed to teach you how to work with natural dyes, but rather the why behind them. if you’re dipping your toe into the waters (maybe with natural dyeing as practiceor natural dyeing 101 or the crush scholarship), it’ll give you a helpful basis from which you can start figuring out what other resources are legit and which are full of shit. if you want the full downloadable guide right now, you can find it with willow’s treats in the creative coven community.

making - understanding natural dyes, a series - the basics, part 1