Flax Processing

Part of Textiles and Weaving

Flax is one of the oldest cultivated fiber plants, producing linen — a fabric prized for its strength, breathability, and durability. Processing flax into spinnable fiber requires multiple stages, each demanding patience and technique.

Linen cloth has clothed civilizations for over 10,000 years. The plant Linum usitatissimum yields both fiber and linseed oil, making it one of the most versatile crops a rebuilding community can grow. But between pulling the plant from the ground and spinning usable thread lies a labor-intensive process that, once mastered, produces fabric far superior to most alternatives available without industrial machinery.

Growing and Harvesting Flax

Flax thrives in cool, moist climates with well-drained soil. Sow seeds densely — about 2,000 seeds per square meter — to encourage tall, straight stems with minimal branching. The plants reach 80-120 cm in height over roughly 100 days.

Harvest Timing

The timing of harvest determines fiber quality:

Harvest Stage	Indicators	Fiber Quality	Seed Viability
Green/early	Lower leaves yellowing, stems still green	Finest, softest fiber	Seeds immature, unusable
Mid-ripeness	Lower 2/3 of stem yellow, seeds turning brown	Good balance of strength and fineness	Some seeds viable
Full ripeness	Stems fully brown, seed capsules rattling	Coarsest, strongest fiber	Fully viable seeds

Best Practice for Rebuilding

Harvest at mid-ripeness to get both usable fiber and seed stock for next year’s crop. In a survival situation, you cannot afford to sacrifice seed viability for marginally finer thread.

Pulling, Not Cutting

Always pull flax by hand — grasp bundles of stems near the base and pull straight up, roots and all. Cutting with a blade disrupts the continuous fiber length that runs the full stem, reducing thread quality. After pulling, remove seed capsules by pulling bundles through a coarse comb or ripple (a board with upright nails). Save these seeds for replanting or pressing for linseed oil.

Tie pulled stems into bundles (called “beets”) about 15 cm in diameter. These bundles will go through retting next.

Retting: Breaking Down the Bast

Retting is the controlled decomposition of the pectin that binds flax fibers to the woody core of the stem. This is the most critical and time-sensitive step in the entire process. Under-ret and the fibers won’t separate cleanly; over-ret and the fibers themselves begin to weaken and decay.

Dew Retting

Spread pulled flax stems in thin, even layers on short grass in an open field. Morning dew, rain, and soil microorganisms gradually break down the pectin binding.

Timeline: 2-6 weeks depending on climate, humidity, and rainfall.

Process:

1. Lay bundles out in rows, stems parallel, one layer thick
2. Turn bundles every 3-5 days for even retting
3. Test daily after week 2 — try to peel fiber from a stem
4. Fiber should separate cleanly with a slight pull when ready
5. Gather immediately when properly retted — delays of even 1-2 days risk over-retting

Over-Retting Destroys Fiber

If fibers feel mushy, crumble, or break easily when bent, the flax is over-retted. There is no recovery. The entire batch may be ruined for textile use, though it can still serve as garden mulch or animal bedding.

Advantages: No equipment needed, suitable for large quantities, minimal labor. Disadvantages: Weather-dependent, uneven results, takes weeks, requires large flat area.

Water Retting

Submerge flax bundles in still or slow-moving water — ponds, ditches, or purpose-built retting pits work well.

Timeline: 4-14 days depending on water temperature.

Water Temperature	Retting Time	Notes
15-20°C (59-68°F)	10-14 days	Slow but controllable
20-25°C (68-77°F)	7-10 days	Ideal range
25-30°C (77-86°F)	4-7 days	Fast — check twice daily
Above 30°C (86°F)	3-5 days	Very high risk of over-retting

Process:

1. Weigh bundles down with stones or logs to keep fully submerged
2. Use stagnant water — flowing water slows bacterial action
3. Check daily by pulling a stem and testing fiber separation
4. When fibers peel cleanly, remove immediately
5. Rinse bundles thoroughly in clean running water
6. Spread to dry completely (2-5 days in sun)

Water Retting Produces Foul Odors

The anaerobic bacterial decomposition releases hydrogen sulfide and butyric acid — the smell is intense and persistent. Site your retting pond well downwind from living areas. Never ret in drinking water sources, as the runoff is toxic to fish and contaminates water.

Advantages: Faster and more uniform than dew retting, produces lighter-colored fiber. Disadvantages: Requires water source, produces terrible smell, can pollute water, needs close monitoring.

Tank Retting (Controlled)

If you have access to large containers (barrels, tanks, lined pits), you can control temperature more precisely. Warm water (25-30°C) with a small amount of wood ash (raises pH slightly, accelerating bacterial action) can ret flax in 4-7 days. Change water once at the midpoint to prevent excessive bacterial buildup.

Breaking: Crushing the Woody Core

After retting and thorough drying, the flax stems are brittle. The woody inner core (called “shive” or “boon”) must be broken away from the outer bast fiber.

Build a flax brake — a simple hinged wooden device with interlocking blades:

1. Cut two boards approximately 60 cm long, 15 cm wide
2. Cut 3-4 parallel grooves into each board, creating interlocking “teeth”
3. Hinge one end so the top board can be slammed down onto the bottom
4. Mount at comfortable working height (waist level)

Technique: Lay a handful of dried, retted stems across the lower blade. Slam the upper blade down repeatedly, working from one end of the bundle to the other. Rotate the bundle and repeat. You should hear and feel the woody core cracking and shattering. Continue until most shive has been broken free.

Drying Is Essential

Flax must be bone-dry before breaking. If stems bend rather than snap, dry them further. Some processors kiln-dry or oven-dry retted flax at low heat (40-50°C) for several hours to ensure complete dryness. Crisp, crackling stems break much more efficiently.

Scutching: Removing Broken Shive

After breaking, the fibers still contain embedded pieces of shive. Scutching removes these fragments.

Tools needed: A scutching board (a vertical plank, about 1 meter tall) and a scutching knife (a flat wooden blade, roughly 40 cm long).

Process:

1. Drape a handful of broken flax over the top edge of the scutching board
2. Hold the fiber bundle firmly at the top with one hand
3. With the other hand, scrape downward along the fibers with the scutching knife
4. The blade action dislodges and flings away loose shive
5. Turn the bundle and scrape the other side
6. Repeat until fibers hang clean and flexible

Work outdoors — scutching produces a blizzard of fine shive particles. A light breeze helps carry debris away. The removed shive makes excellent fire kindling, animal bedding, or garden mulch.

Hackling: Combing and Grading Fibers

Hackling separates fibers by fineness and removes any remaining shive or short, tangled fibers. You need a hackle — a board set with rows of sharp metal or wooden pins.

Building a Hackle

Drive steel nails or sharpened wire pins into a wooden block in rows, points up:

Hackle Grade	Pin Spacing	Pin Count	Purpose
Coarse	15-20 mm	20-30 pins	First pass, removes large debris
Medium	8-12 mm	40-60 pins	Separates fiber grades
Fine	3-5 mm	80-120 pins	Final combing for spinning-quality fiber

Process:

1. Start with the coarse hackle — draw the fiber bundle through the pins
2. Begin near the tips, gradually working deeper into the bundle
3. Short, broken fibers (tow) will catch in the pins — set these aside
4. Progress to the medium hackle, then the fine hackle
5. The long, aligned fibers that pass cleanly through the fine hackle are “line fiber”

Fiber Grades

• Line fiber (strick): Long, parallel, fine fibers — 30-90 cm. Used for high-quality linen thread. Smooth, lustrous, strong.
• Tow: Short, tangled fibers caught in the hackle. Coarser and weaker but still useful for rough rope, twine, coarse fabric, stuffing, or paper-making.

Save Everything

In a rebuilding scenario, discard nothing. Line fiber makes clothing-grade linen. Tow makes rope, bags, rough cloth, insulation, and papermaking stock. Shive serves as kindling, mulch, or building insulation. Seed capsules yield oil and next year’s crop.

From Fiber to Thread

After hackling, line fiber is ready for spinning. Flax fiber behaves differently from wool:

• It has no crimp or elasticity — drafting must be gentle and consistent
• Wet spinning produces smoother, stronger thread — keep fingers moist
• Flax fibers are slippery — a distaff helps keep the fiber supply organized and under tension
• Spin with a worsted (parallel fiber) technique, not woolen (jumbled fiber)

A traditional flax distaff holds the hackled fiber bundle upright near the spinner’s left hand, allowing controlled drafting while the right hand manages the spindle or wheel.

Thread Quality by Fiber Grade

Fiber Grade	Suitable Thread	Typical Use
Fine line	Thin, smooth singles or 2-ply	Shirts, undergarments, sheets
Coarse line	Medium singles or 2-ply	Outer clothing, towels, sacks
Tow	Thick, rough singles	Rope, twine, coarse bags, wicks

Yield Expectations

Understanding realistic yields helps plan how much flax to grow:

Stage	Input	Output	Loss
Harvest	1 hectare planted	~5,000 kg raw stems	—
Retting + Drying	5,000 kg stems	~4,000 kg retted	20%
Breaking + Scutching	4,000 kg retted	~800 kg raw fiber	80% (shive removed)
Hackling	800 kg raw fiber	~400 kg line + 300 kg tow	~12% waste
Spinning	400 kg line fiber	~380 kg linen thread	~5% waste

A single linen shirt requires approximately 2-3 kg of finished thread, meaning one hectare of flax produces enough line fiber for roughly 130-190 shirts. However, this represents hundreds of hours of manual processing labor.

Start Small

For a first attempt, plant a 3x3 meter test patch. This yields enough fiber to learn every stage of the process and spin enough thread for a small project — a handkerchief, a pouch, or enough twine for practical use.

Troubleshooting Common Problems

Problem	Likely Cause	Solution
Fibers won’t separate from stem	Under-retted	Continue retting, check daily
Fibers are weak and break easily	Over-retted	Cannot be fixed; use as tow or mulch
Uneven retting across batch	Inconsistent submersion or turning	Turn bundles more frequently, ensure full submersion
Dark discoloration	Prolonged water retting or dirty water	Cosmetic only; fiber still usable, bleach in sun
Excessive shive after scutching	Insufficient breaking	Re-break with more vigorous blade action
Fiber tangles during hackling	Hackle too fine for first pass	Start with coarser hackle, work gradually finer

Storage and Preservation

Properly processed flax fiber stores indefinitely if kept dry. Bundle hackled fiber into “stricks” — neat hanks tied loosely. Store in a dry location away from rodents (they nest in fiber). Tow can be stored loose in sacks.

Linen thread and fabric actually improve with use and washing — they soften without losing strength, unlike cotton which degrades. A well-made linen garment lasts decades, making the processing effort worthwhile.

Flax Processing Summary

Flax processing follows a strict sequence: harvest (pull, don’t cut, at mid-ripeness) → ret (dew ret 2-6 weeks outdoors, or water ret 4-14 days submerged) → dry thoroughly → break (crush woody core with hinged brake) → scutch (scrape away shive fragments) → hackle (comb through progressively finer pins to separate line fiber from tow). The entire process from harvest to spinnable fiber takes 3-8 weeks and yields roughly 8% of the original stem weight as high-quality line fiber. Save everything — line fiber for fine thread, tow for rope and rough cloth, shive for kindling and mulch, seeds for replanting and oil. Start with a small test plot to learn the process before scaling up.