Natural pigments and dyes

Dyeing with natural dyes is a process in which plant, animal, or mineral pigments are used to color fabrics. Unlike synthetic dyes, natural dyes require preliminary fiber preparation and special treatment to achieve lasting results.

NATURAL DYEING MANUAL

Basic Dyeing Supplies:

The following items are needed for natural dyeing:

natural fiber fabrics,
pots of various sizes, strainers, hot plates,
baking soda and washing soda,
aluminum sulfate (alum) and iron sulfate,
dye source (plants, fruits, peels...),
scale.

Fabric Selection

Synthetic fibers, such as polyester, are hydrophobic and therefore unsuitable for natural dyeing. Only natural fibers are used, which are divided into two main groups:

Cellulose fibers: Plant-based (e.g., cotton, linen, denim), composed of cellulose,
Protein fibers: Animal-based (e.g., wool, silk), composed of proteins (keratin).

Protein fibers bind natural dyes more effectively, therefore they usually achieve more intense colors. Cellulose fibers, however, require more complex preparation processes (mordanting).

Note: Protein fibers are sensitive to heat; boiling them for too long can cause shrinkage or felting.

Fabric swatches measuring 15 × 15 cm made of silk, wool, linen, cotton, and denim are often used for dye testing.

WOF (Weight of Fibres)

The weight of fibers (WOF) is the fundamental unit of measurement in the dyeing process. All ingredients and chemicals are measured relative to the weight of the fabric.

Example: 1 kg of fabric = 100 g of washing soda (10% WOF).

Fiber Cleaning

Before dyeing, fabrics must be cleaned of fats, waxes, and dirt. The process varies depending on the type of fiber:

Cellulose fibers: Clean with washing soda (10% WOF). Boil the fabric for one hour in water with soda. Dissolve the washing soda in enough water to completely cover the textile. Bring the water with the textile to a boil and simmer for approximately one hour.
Protein fibers: Clean with baking soda (1 tablespoon per 1 liter of water). Soak for 30 minutes.

After cleaning, rinse the fabric in lukewarm water and either dry it or proceed immediately with mordanting.

Mordanting

Mordanting is the pre-treatment of fabrics to improve dye binding and achieve colorfastness. Mineral salts (alum, iron), plant tannins, and soymilk are used.

Tannin Bath

Used primarily for cellulose fibers (e.g., cotton, linen).

Dosage: 10% WOF of tannin.
Dissolve the tannin in hot water, then mix it into lukewarm water. Use a large container and ensure the textile is fully submerged in the bath.
Soaking: Overnight in a lukewarm bath, followed by rinsing.

Note: We used pure tannin (https://www.revivo.si/tanin_vodotopen_500g), which was quite dark and significantly affected the color of the textile. We recommend using a lighter-colored tannin or soaking in the bath for a shorter time (e.g., 30 minutes).

Alum and Iron

Alum (aluminum sulfate): 10% WOF, produces lighter tones.
Iron sulfate: 2% WOF, produces darker tones.

Weigh the alum or iron sulfate and dissolve it in a bath of lukewarm water, then add the textile. We decided to let the fabric soak overnight. This step doesn't need to be that long; successful results can also be achieved by soaking the fabric in the bath for 1-2 hours. However, in natural dyeing, the principle generally applies that the longer the material soaks, the more lasting the results one can expect. It is ideal to stir the textile during soaking for more even color.

Warning: For both processes, it is worth mentioning that we ensured proper protection when handling the textiles. Although these are not toxic substances, wearing gloves is still advisable, as some individuals may experience an allergic reaction. If contact with skin occurs, rinse the affected area with water.

Soy Milk

Used exclusively for cellulose fibers, as it creates a protein layer.

Ratio: 1 part soy milk : 4 parts water.
Process: Soak for 15 min, wring out, dry; repeat the process 3 times. The fabric needs a few days to rest and 'mature'.

Preparation of Dye Baths

Preparing the dye baths is the final step of the wet process. The rule here is: the more raw material we have, the more colored the bath will be. This also means, of course, that our final fabric will be more pigmented than otherwise. Still, as a guideline for a good ratio, we have the weight of the fabric, which should be equal to the weight of the raw material used to prepare the dye bath: equal weight of raw material and fabric (1 : 1).

Process:

Weigh the fabric and the raw material.
Boil the raw material in water until the desired intensity is reached.
Submerge the fabric in the lukewarm dye bath (it's best if the fabric floats freely in the bath).
Let the fabric soak for 2 hours to overnight.
Rinse in lukewarm water and dry away from sunlight.

The results of dyeing depend on numerous factors (type of fabric, amount of pigment, pH, soaking time).

Fabric Dyeing

The dyeing process itself follows these steps:

Fabric Preparation – Dampen the dry fabric or use already washed fabric, depending on the fixation process (whether it was dried or not).
Immersion in the Bath – Completely submerge the fabric in the dye bath. Squeeze out air from the fabric (air bubbles can cause uneven dyeing).
Stirring – Gentle stirring is recommended to distribute the pigment evenly and prevent pooling in folds.
Soaking – Leave the fabric in the dye bath for at least 2 hours or overnight; longer times result in more intense color.
Finishing – After dyeing, rinse the fabric with lukewarm water, dry at room temperature, and away from sunlight.

Vpliv dejavnikov

Rezultati barvanja se lahko razlikujejo kljub enakim postopkom. Na končno barvo vplivajo:

vrsta in gostota tekstila,
količina uporabljene surovine,
vrsta vlakna in njegova sposobnost vezave pigmentov,
pH kopeli,
čas namakanja,
način mešanja,
način in čas sušenja ter shranjevanja.

Tako lahko npr. rdeče zelje enkrat da modre, drugič pa vijolične odtenke, odvisno od pogojev.

Vpliv pH na barve

Spreminjanje pH barvne kopeli omogoča pridobivanje različnih barvnih odtenkov:

kisla kopel (kis): barve postanejo svetlejše ali spremenijo odtenek (npr. zelena → roza),
bazična kopel (soda bikarbona): barve postanejo intenzivnejše.

Pri posotpku izdelave in razvoja barv, uporabimo sodo bikarbono za izdelavo bazične kopeli in alkoholni kis za izdelavo kisle. Kis velikokrat spremeni barve v bolj svetle ali celo popolnoma drugačne od tiste, ki je bila prvotno pridobljena. Recimo – zelena barvna kopel travniškega žajblja se ob kapljici dodanega kisa spremeni v roza barvo. Dodatek sode bikarbone, pa velikokrat bolj saturira barvno kopel, tako da dobimo močnejše barve kot bi jih sicer. Uporaba obeh dodatkov količinsko je poljubna in reakcija je takojšna.

Tehnika Shibori

Shibori je japonska tehnika zavezovanja, šivanja ali gubanja blaga pred barvanjem, s čimer nastajajo vzorci. Pogosto se uporablja v kombinaciji z naravnimi barvili (npr. kopel zlate čebule).

Barvni sklopi

Kopeli smo, glede na surovino, razdelili v 4 barvne sklope:

Rumena: travniška detelja, tagetes, kurkuma, zlata čebula, lesna goba.
Rdeča: pelargonija, navadni brošč, olupki granatnega jabolka, avokadovi olupki, avokadove peške, rdeča čebula.
Modra: rdeče zelje, črn fižol, aronija, kombinirane kopeli.
Zelena: travniški žajbelj, meta, perje koreja, brezovo listje, kombinirane kopeli.

Izolacija pigmentov iz barvnih kopeli

Poleg barvanja tkanin lahko iz že uporabljenih barvnih kopeli pridobimo suhe pigmente v prahu. Ti so uporabni za tiskarske paste, barvanje biomaterialov in druge umetniške ali tekstilne aplikacije.

Potrebne sestavine in pripomočki

približno 500 ml barvne kopeli,
18 g aluma (aluminijev sulfat),
8 g sode bikarbone,
posoda z dovolj prostora,
filter (npr. laboratorijski papir ali gosto blago),
žlica za mešanje.

Postopek

1. Dodajanje v barvno kopel

V posodo z barvno kopeljo med mešanjem počasi vlijemo raztopino aluma.
Nato med stalnim mešanjem počasi dodajamo raztopino sode bikarbone.

2. Reakcija

Ob stiku obeh raztopin pride do kemične reakcije: tekočina se začne peniti, v kopeli pa se oblikuje oborina (pigment).
Med reakcijo mešamo vsaj 2 minuti, da se pigmenti vežejo s soljo v vodi.

3. Ločevanje faz

Počakamo, da se tekočina loči na dve plasti: zgornjo (tekočo) in spodnjo (gosto, s pigmentom).
Zgornjo plast previdno odlijemo.

4. Filtriranje

Spodnjo plast s pigmentom prelijemo čez filter.
Pigment pustimo na filtru, da se popolnoma posuši.

5. Mletje

Posušen pigment zdrobimo v fin prah. Tako dobimo barvilo v suhi obliki.

Uporaba pigmentov

Pigment lahko zmešamo z različnimi vezivi (naravnimi ali sintetičnimi).
V praksi so pigmenti pogosto dodani pasti za sitotisk, s katero se nato tiska na bombaž ali druge tkanine.
Pigmenti so uporabni tudi za barvanje biomaterialov (npr. kombinacija žagovine in alginata).

Avtor_ica: Zeleni Lab (Center Rog), Tekstilni lab (center Rog), leto: 2025.

To delo je licencirano pod Creative Commons Priznanje avtorstva – Nepridobitno 4.0 Mednarodna licenca. Več informacij: CC-BY-NC 4.0