Dyeing can be done in various stages of the processing of wool, both before the spinning, in the yarn or after weaving. Traditionally, plants were used for this purpose as a wild mignonette, (dyers') woad and madder below.

Mordanting
To have a good ”catch” of dye on wool, the wool is first stained with potassium dichromate (orange powder that gives a yellowish effect), tartaric (fine white powder), alum and previously urine. The scales on the wool fiber are opened thereby allowing the dye can adhere better to the wool. Most natural dyes need a mordant to fix the color to the fiber and increase lightfastness.
Alum is the most widely used non-toxic mordant. Pour in a (not aluminum) pan 15-20 grams of alum per 100 grams of wool in more than lukewarm water. Put the wool in. Bring slowly to boil and let simmer for 1 hour. Let the water cool down to about 40 degrees and you can start painting. (It can also be done later if you have the wool left to dry slowly.)

Iron sulphate and copper sulphateis used for fixation or mordating after dyeing. They make the color darker.

Yellow / orange

The wild (or yellow) mignonette (Reseda luteola) grows in the Mediterranean region, and was also widely grown in the area around the East Flemish town of Aalst. It is an annual or biennial plant, which blooms with bright yellow flowers in June to September. The plant can be high up to 1m in a sunny place. Harvesting must take place before the seed shoots. Mignonette contain the dyes luteolin and apigenin that paint yellow. The largest concentrations are in the tops of the shoots and in the seeds.
Mignonette was first boiled in water with old urine to promote the extraction of the dyes. For dyeing textiles alum and bran are used as mordant.
When dyeing wool, the whole plant is used: 200 gr. for 100 gr. wool.

Bright yellow, you also get from goldenrod or poplar buds.
Please note that when dyeing with onion skins (Allium cepa), the desired color goes from bright yellow to orange - golden brown.
Tansy (Tanacetum vulgare): flowering tops
Juniper (Juniperus communis): freshly crushed berries
Coltsfoot (ass’s foot,..) (Tussilago farfara): whole plant
Privet (Ligustrum vulgare) leaves and young shoots
Heather (Calluna vulgaris): young tops
Dyer’s broom (or –greenweed) (Genista tinctoria): flowering tops  Dyer’s (or yellow) chamomile (Anthemis tinctoria): flowers
Orange lichen(Xanthoria parietina) (protected) gives soft yellow.


Green
Bracken (Pteridium aquilinum): young shoots
Nettle (Urtica dioica): whole plant
Privet (Ligustrum vulgare): ripe berries
Wild ginger (Asarum europaeum): root
Heather (Calluna vulgaris): fresh sprigs
Elderberry (Sambucus nigra): leaf
Birch Leaf gives fresh green


Blue

(Dyers') woad or glastum (Isatis tinctoria) is a plant of the cabbage family (Brassicaceae). There can be extracted indigo from. The plant can reach 1 m high. The yellow flowers have four petals and grow in bunches.

The woad is harvested, cut in pieces and entered into a rotting process. Then kneaded in a clay like ball and dried. The ball is with bran and water (possibly with madder) fermented. After one or two days, this gives a yellow - greenish liquid.
White wool is dipped into the liquid ten seconds. We see now that the wool colors blue.
Also, ammonia (or old urine to colorfast mordanting) may in a warm water bath with 1,000 g. leaves for 40 gr. wool.
Drying usually happened on Monday so that the painters had not much to do that day. Hence the expression ”Blue Monday”.

Purple / blue
Alkanet or dyers' bugloss (Alkanna tinctoria) (root) gives shades of gray blue and purple.
If you let ferment lichens (protected!) you also get pretty purple.
Bearberry (Arctostaphylos uva - ursi): dried leaves with alum
Elderberry (Sambucus nigra) (and blueberry): berries


Red (pink and orange)

The (common) madder or dyer's madder (Rubia tinctorum) is a plant from Asia Minor and the eastern part of the Mediterranean. From the 12th century it also comes in Flanders (later in Zeeland and South Holland islands). She has little hooks with which the almost underlying plant adheres to surrounding vegetation and establishes.
The plant is 60-90 cm high and has small yellow flowers. The rhizomes can go 50-100 cm deep. From the roots, you can extract red madder which is used mainly to color textiles and leather. The raw material for the red dye is alizarin, mainly found in the thinner adventitious roots. Madder provided the raw material for the brightly colored, red farmer handkerchiefs. Young shoots of the biennial plant were smeared through the mud and then planted in well-fertilized soil. The rhizome is harvested in September after three years, one year dried, and then ground. The powder is treated with water vapor and acid. Thereafter, aluminum and / or tin-containing salts are added. The resulting dye is soluble in water and can be used for dyeing tissues.

In 1868, it was discovered in Germany how alizarin could be prepared synthetically. The cultivation of madder thus died softly.

To dye wool 25-50 grams root powder is required per 100 grams of wool.

The madder is family of the cleavers (Galium aparine, like goosegrass) whose roots can be used to get an orange tint.
Alkanet (Anchusa officinalis): root
Bedstraw (Galium verum or mollugo): root
Sorrel (Rumex acetosa): root

The bark of (European mountain) ash (Sorbus aucuparia) (red or brown).

Leaf of alder can be used to color beige.

Brown coloring can with ground elder (or Bischop’s weed, Aegopodium podagraria), or the leaves of coltsfoot (ass’s foot,..) (Tussilago farfara), flowers of tansy (Tanacetum vulgare). Shred them in a pan, add more than lukewarm water and mordanted wool. Let this simmer for an hour.
Blackberry (Rubus sp.): young shoots
Juniper (Juniperus communis): dried berries, crushed
Walnut (Juglans regia): leaf, green shell and husk
With walnut leaves can also not mordanted wool be painted, which gives a different color brown.

Black
Bearberry (Arctostaphylos uva - ursi): dried leaf with iron
Elderberry (Sambucus nigra) bark
Meadowsweet (Filipendula ulmaria): root


Wool you better air instead of washing. If you wash, do it gently with warm water, without soaking or wringing. Otherwise you risk that you're making felt.

(See also <Pigment>)

At a traffic light. Says one: "It's green." Says another: "A frog."