An Introduction to the Dye Process

These simple instructions will get you started for most dyes. As you become a more knowledgeable and experienced natural dyer, you will learn that there are thousands of process variations, that some dyes require other variables to be addressed to maximize the colour they give, etc.
But the below is intended to provide a user-friendly entry point to making and using a simple dye bath, so that you can jump right in and start to build some confidence.
First, you need to understand the importance of scouring and mordanting for good results.
As a general rule, you do not need to prepare your dye bath differently for protein (Animal Kingdom) and cellulose (Plant Kingdom) fibres. But you do need to scour and mordant your fibres differently, so please read through the information at the scouring and mordanting link above.

What to Use as a Dye

The below relates to water soluble dyes (which is most natural dyes). Completely different, more complicated processes are required for dyes that are not water soluble (such as indigo), which are not recommended for beginners.
Most classic plant dyes are derived from roots, wood, and some flowers. Reliable natural dyes from some flowers do exist (e.g. Marigold, Dyer’s Chamomile, Goldenrod, etc.), but the vast majority of flowers contain highly fugitive colourants that will fade and wash out very quickly. Kitchen edibles, such as purple cabbage, beets, black beans, berries and other fruits also contain these highly fugitive colourants, which can not accurately be called ‘dyes’.
As a beginner, you want to build confidence, so start with classic, tried and true dyes. Don’t waste your time on highly fugitive flowers or edibles.

Maximizing surface area on your dye material will maximize dye extraction. So, with foraged materials, cut it up into small pieces.
Always use a dye pot big enough that your quantity of fibre can move freely. Over-crowding results in poor/uneven dye results.
Many dye compounds are destroyed by high heat, so it is best to keep most dye baths to a simmer, or just below a simmer. Never boil.
Water plays an enormous role in your dye results, so get to know your water supply. Rain water is considered best (most pure), but not everyone has access to it, so use and learn about your own water supply - is it hard or soft, is it treated or un-treated, etc.
Add all fibres (i.e. multiple skeins) to dye bath at same time for most consistent colour.
Wet dyed fibres will appear several shades darker than when dry.
As with scouring and mordanting, a non-reactive pot will give you good results, and is best for beginners so that you get the clearest picture of the effect of the dye itself. However, many dyers intentionally use reactive pots to shift their dye colours - iron to ‘sadden’ (deepen) colours, unlined copper to push yellow dyes to green, etc.

If you are using foraged materials, rinse them to remove soil, etc.
Weigh your fibres. This is known to natural dyers as WOF - Weight of Fibre.
Weigh your dye material at whatever WOF you want to try. With fresh/foraged plant material, 100% WOF is a good place to start. With purchased dye materials, the supplier will provide recommended WOF.
Add your dye material to your pot. If you add the material loose, you will have to strain it before adding the fibres. If you add the material in a pouch, removal is much easier. You can use any un-mordanted material for your pouch, with a weave tight enough to prevent dye material particulates from escaping into the bath. Most natural fibres will allow for the passage of the actual dye molecules from the interior of the pouch into your dye bath.
Bring your bath to just below a simmer and hold for one hour to extract colour. If you are happy with the colour extracted at this stage, you can remove the dye material and proceed to dyeing straight away. Or you can take the pot off the heat, cover and leave overnight for maximum dye extraction. The next morning, remove the dye material.

Pre-saok your fibres in hottest tap water for at least 1 hour. This opens up the fibres, making them better able to maximize dye uptake.
Return your strained dye bath to just below a simmer, or a simmer.
Wring out your pre-wetted fibres and add to the dye bath, stirring gently to expose all fibre surfaces.
Hold at temperature for an hour. Every 15 minutes or so, move your fibres (being very gentle with wool to avoid felting) to ensure the most even dye uptake.
After one hour, if you are happy with the colour uptake at this stage, you can remove your fibres. Or you can take the pot off the heat, cover and leave overnight for maximum dye uptake. The next morning, remove your fibres.

Rinse your fibres in water of the same temperature (particularly important for wool to avoid felting) until the water runs clear. Un-bonded dye particulates left on the surface of the fibres can cause spotting/un-even results.
Hang or lay flat to dry.

After dyeing your initial fibres, add additional scoured and mordanted fibres to your leftover dye for softer shades. This is known as exhaust dyeing.