Fiber Preparation

Part of Natural Dyes & Inks

Preparing raw fibers to accept and retain natural dyes through scouring, mordanting, and pre-treatment steps.

Why This Matters

In a rebuilding scenario, dyeing fabric is only as good as the preparation that precedes it. Unprepared fibers contain natural oils, waxes, pectins, and sizing agents that physically block dye molecules from bonding with the fiber. Skipping preparation means wasted dye materials, uneven color, and textiles that fade to nothing after a few washes. When every resource is precious, you cannot afford to ruin a batch of laboriously gathered indigo or madder because the cloth was not properly scoured.

Fiber preparation is the unglamorous foundation of the entire dyeing craft. The difference between a richly colored, permanent dye job and a disappointing, blotchy mess almost always comes down to what happened before the fiber ever touched the dye bath. Understanding which fibers need which treatments, and why protein fibers behave differently from cellulose fibers, gives you predictable, repeatable results with whatever dye plants your region provides.

Mastering these techniques also extends the useful life of textiles dramatically. Well-prepared and well-dyed cloth resists fading and maintains its appearance through years of use, reducing the constant pressure to produce replacement garments and trade goods.

Fiber Types and Their Properties

All natural fibers fall into two broad categories, and each demands a different preparation approach.

Protein Fibers (Animal Origin)

Fiber	Source	Key Characteristics
Wool	Sheep	Heavy lanolin coating, scales on surface
Silk	Silkworm cocoons	Sericin gum coating, smooth surface
Alpaca	Alpaca fleece	Less lanolin than wool, fine scales
Hair fibers	Goat, rabbit, horse	Variable grease content

Protein fibers have an amino acid structure that bonds readily with acid dyes and many natural dye molecules. Their main contaminants are animal grease (lanolin in wool) and natural gums (sericin in silk). These fibers are sensitive to high pH and excessive heat, which can cause felting in wool or damage silk’s luster.

Cellulose Fibers (Plant Origin)

Fiber	Source	Key Characteristics
Cotton	Cotton bolls	Waxy cuticle, seed oils
Linen	Flax stems	Pectins, woody fragments
Hemp	Hemp stems	Heavy pectins, lignin residues
Nettle	Nettle stems	Similar to hemp
Ramie	Ramie plant	Gums and pectins

Cellulose fibers have a hydroxyl-group structure that bonds differently from protein fibers. They generally require more aggressive mordanting and often benefit from a tannin pre-treatment to create bonding sites for metallic mordants. They tolerate higher temperatures and alkaline conditions better than protein fibers.

Scouring: Removing Natural Contaminants

Scouring is the essential first step that strips away everything preventing dye contact with the actual fiber.

Scouring Wool

1. Fill a vessel with enough water to allow the fiber to move freely — roughly a 30:1 water-to-fiber ratio by weight
2. Heat water to 50-60°C (hot but not scalding — you should be able to hold your hand in briefly)
3. Add a surfactant: wood ash lye (mild), soapwort root decoction, or rendered soap at roughly 5% of fiber weight
4. Submerge the wool gently — do not agitate, wring, or stir vigorously, as temperature changes and mechanical action cause felting
5. Soak for 30-45 minutes, gently pressing the fiber below the surface occasionally
6. Drain and repeat with fresh hot water and surfactant if the water is still cloudy or greasy
7. Rinse in progressively cooler water (never shock wool with a sudden temperature drop) until water runs clear

Felting Risk

Wool felts when subjected to heat + agitation + pH change simultaneously. Always change temperature gradually and handle wet wool gently.

Scouring Cotton and Linen

Cellulose fibers are tougher and tolerate aggressive treatment:

1. Prepare an alkaline bath: dissolve wood ash lye or washing soda (sodium carbonate from burned seaweed or trona deposits) at roughly 10% of fiber weight in water
2. Bring to a gentle boil with the fiber submerged
3. Simmer for 1-2 hours, stirring occasionally
4. Check progress: properly scoured cotton will absorb a drop of water instantly rather than letting it bead on the surface
5. Rinse thoroughly in clean water to remove all alkali
6. Repeat if needed — heavily sized or greasy cotton may require two scours

The Water Drop Test

The simplest test for adequate scouring: place a single drop of water on the fiber surface. If it soaks in within 2-3 seconds, the fiber is clean. If it beads up or sits on the surface, more scouring is needed.

Mordanting: Creating Dye Bond Sites

Mordants are metallic salts that form a chemical bridge between the fiber and the dye molecule. Without mordanting, most natural dyes produce only pale, fugitive colors.

Alum Mordanting (Most Common)

Alum (potassium aluminum sulfate) is the safest and most versatile mordant. It occurs naturally in certain clay deposits and can be extracted by leaching aluminous shales.

For protein fibers (wool, silk):

1. Dissolve alum at 15-20% of dry fiber weight in warm water
2. Add cream of tartar (from wine barrel deposits) at 6% of fiber weight — this softens the fiber and brightens colors
3. Heat the bath to 80-90°C (just below simmering for wool)
4. Add wetted fiber and maintain temperature for 45-60 minutes
5. Remove from heat, allow to cool in the bath
6. Remove fiber, gently squeeze out excess, and store damp in a sealed container for up to a week before dyeing

For cellulose fibers (cotton, linen):

1. First apply a tannin pre-treatment (see Tannin Fixation)
2. Dissolve alum at 20-25% of dry fiber weight
3. Soak the tannin-treated fiber in the alum bath at 50-60°C for 1-2 hours
4. Remove, squeeze gently, and repeat the tannin-alum cycle 2-3 times for best results

Iron Mordanting

Iron (ferrous sulfate) darkens and saddens colors. It can be made by dissolving iron nails or filings in vinegar. Use at only 2-4% of fiber weight, as excess iron damages fibers over time. See Iron Modifier for detailed methods.

Other Historical Mordants

Mordant	Source	Effect	Caution
Copper sulfate	Blue vitriol from copper mines	Greens and blue-greens	Toxic — handle carefully
Tin (stannous chloride)	Tin dissolved in acid	Brightens colors	Makes fibers brittle
Chrome (potassium dichromate)	Chromite ore	Rich, deep colors	Highly toxic — avoid

Practical Recommendation

For rebuilding purposes, stick with alum and iron. They are the safest, most available, and cover the vast majority of color possibilities. Alum for bright colors, iron for darks and olives.

Pre-Wetting and Bath Entry

A detail that many beginners skip but experienced dyers never neglect:

1. Always pre-wet fibers before entering any bath (mordant or dye). Dry fiber traps air bubbles that create undyed spots
2. Soak in plain warm water for at least 30 minutes before transferring to the mordant or dye bath
3. Enter the bath at the same temperature as the soak water — sudden temperature changes cause uneven absorption and, in wool, felting
4. Squeeze out excess water gently before transferring — you want the fiber damp, not dripping, to avoid diluting the bath

Preparing Specific Fiber Forms

The physical form of your fiber affects preparation:

Raw Fleece

• Skirt the fleece first (remove heavily soiled belly and leg wool)
• Pick out vegetable matter, dung tags, and second cuts
• Scour in mesh bags or loosely tied bundles to prevent tangling
• Mordant in the same loose form

Spun Yarn

• Wind into loose skeins tied in at least four places with figure-eight ties
• Use ties of a contrasting fiber or cotton string so they do not dye and can be identified
• Handle skeins gently to avoid tangling — tangled wet yarn is extremely difficult to salvage

Woven Cloth

• Hem or serge raw edges before scouring to prevent unraveling
• Accordion-fold rather than bunching to ensure even contact with scouring and mordant solutions
• For large pieces, use a stick to lift and turn the fabric in the bath

Timing and Storage

• Mordanted fiber can be stored damp in a sealed vessel for up to one week, or dried and stored for several months
• Damp storage gives slightly better results as the mordant remains evenly distributed
• Dried mordanted fiber should be thoroughly re-wetted before dyeing
• Record keeping: mark skeins or fabric with different colored ties to track which mordant was used — this becomes critical when you are running multiple dye experiments

Troubleshooting Common Problems

Problem	Likely Cause	Solution
Uneven color	Insufficient scouring or dry spots	Re-scour, ensure complete wetting
Pale color despite adequate dye	No mordant or weak mordant	Re-mordant and re-dye
Harsh, brittle fiber	Too much iron mordant or too long in alkaline scour	Use less mordant; reduce scour time
Felted wool	Too much agitation or temperature shock	Handle gently, change temperature gradually
Spots or streaks	Undissolved mordant crystals	Always fully dissolve mordant before adding fiber
Color rubs off	Dye sitting on surface, not bonded	Inadequate mordanting; try tannin pre-treatment

Proper fiber preparation is not glamorous work, but it is the single most important factor in achieving beautiful, lasting color from natural dyes. Master these fundamentals, and every dyeing session that follows will produce reliable, satisfying results.