Retting Process

Part of Knots and Cordage

Retting is the controlled decomposition of plant stems to separate usable bast fibers from the woody core and outer bark. It is the single most important processing step between raw plant material and functional cordage.

Why Retting Matters

You cannot make strong rope from raw bark. The fibers you need — long, flexible bast fibers running just beneath the outer bark — are glued to the woody core by pectins, lignins, and other plant compounds. Retting uses water and microbial action to dissolve those binding agents, freeing the fibers so they can be separated cleanly.

Skip retting and you get brittle, short fibers that snap under tension. Over-ret and the fibers themselves begin to decompose, turning to mush. The window between “not ready” and “ruined” can be as narrow as 12 hours in warm conditions. Learning to read the signs is essential.

Retting Methods

There are three primary approaches, each suited to different situations.

Dew Retting (Field Retting)

The simplest method. Spread harvested plant stalks in a thin, even layer on short grass or bare ground. Morning dew, rain, and ground moisture provide the water. Fungi and bacteria do the work.

Factor	Detail
Time required	2-6 weeks depending on climate
Best conditions	Warm days (60-85°F / 15-30°C), regular dew or light rain
Turn frequency	Every 2-3 days to ensure even decomposition
Best for	Large batches when time is not critical

Procedure:

1. Harvest stalks at the right stage — after flowering but before seeds fully mature for most bast-fiber plants (nettle, flax, hemp, dogbane).
2. Remove leaves by running your hand down the stalk from top to bottom.
3. Lay stalks parallel in rows no more than 2-3 inches deep on grass or earth.
4. Turn the entire spread every 2-3 days. This prevents uneven rotting and mold concentration on the ground-facing side.
5. Test daily after the first week (see Testing section below).

Mold and Over-Retting

In humid climates, dew retting can proceed too quickly. Black mold on fibers is a sign of over-retting. If you see it, pull the batch immediately and dry the stalks. Some fiber may be salvageable.

Water Retting (Pond or Stream Retting)

Faster and more controllable than dew retting. Submerge bundled stalks in standing or slow-moving water.

Procedure:

1. Bundle stalks into sheaves roughly 6-8 inches in diameter, tied at both ends.
2. Weigh bundles down with stones in a pond, ditch, slow stream, or any container of water. Stalks must stay fully submerged.
3. Use stagnant or slow-moving water — fast current washes away the bacteria doing the work.
4. Change water every 2-3 days if using a container. Stagnant retting water becomes foul-smelling (hydrogen sulfide) and can contaminate drinking water sources.
5. Check daily starting at day 3 in warm weather, day 7 in cool weather.

Factor	Detail
Time required	4-14 days (warm water) to 2-3 weeks (cold water)
Water temperature	Ideal: 75-90°F (24-32°C)
Container options	Any watertight vessel, plastic bin, hollowed log, lined pit
Best for	Moderate batches when faster processing is needed

Water Source Contamination

Never ret fibers in or upstream of drinking water. Retting produces toxic anaerobic byproducts that kill fish and contaminate water. Use a separate pond, ditch, or container set well away from your water supply.

Warm Water / Accelerated Retting

The fastest method, useful when you need cordage urgently.

Procedure:

1. Cut stalks into manageable lengths (18-24 inches).
2. Place in a container of warm water — 90-100°F (32-38°C) is ideal.
3. If possible, add a handful of already-retted material or pond mud as a bacterial starter culture.
4. Keep water warm. In a survival context, set the container near a fire or in direct sunlight with a dark-colored cover.
5. Change water every 24 hours. The water will turn dark brown and smell strongly.
6. Check fibers starting at 48 hours.

Factor	Detail
Time required	2-5 days
Temperature	90-100°F (32-38°C) ideal
Risks	Easiest method to over-ret — check frequently
Best for	Urgent need, small batches

Testing for Completion

Retting is done when the fibers separate cleanly from the woody core. Here is how to test:

1. Snap Test: Take a single stalk and bend it sharply. The woody core should snap cleanly. If it bends without breaking, retting is incomplete.
2. Peel Test: At the snap point, grip the broken woody core and pull it away from the outer material. The fibers should peel away in long, clean strips without tearing or requiring force.
3. Twist Test: Take a small bundle of separated fibers and twist them between your fingers. They should feel smooth, flexible, and silky — not gritty, stiff, or crumbly.
4. Strength Test: Pull a single fiber strand between your hands. Properly retted fiber resists breaking and stretches slightly before snapping. Over-retted fiber crumbles or breaks with minimal force.

The Goldilocks Zone

When 80% of your test stalks pass all four tests, pull the entire batch. The remaining 20% will catch up during the drying and breaking stages. Waiting for 100% completion risks over-retting the majority.

Post-Retting Processing

Retting is only the first step. After retting, you must process the fibers before they are ready for cordage.

Step 1: Rinse and Dry

Rinse retted stalks thoroughly in clean water to halt bacterial action. Spread them to dry completely — at least 24-48 hours in warm, breezy conditions. Fibers must be fully dry before the next step or they will mold in storage.

Step 2: Breaking

Crush the dried stalks to fragment the woody core inside. Methods:

• Beat stalks gently with a smooth stick or flat stone against a hard surface.
• Roll stalks back and forth under a flat board.
• Flex stalks repeatedly by hand, working along their full length.

The goal is to shatter the inner core into small pieces without cutting the long outer fibers.

Step 3: Scutching

Remove the broken woody fragments (called shives or hurds) from the fibers:

• Hold a bundle of broken stalks at one end and scrape downward with a dull blade, flat stick, or the edge of a board.
• Work from the held end outward, letting shives fall away.
• Flip and repeat from the other end.

Step 4: Hackling (Optional)

For the finest cordage, draw the scutched fibers through a coarse comb — a row of nails driven through a board works well. This separates individual fibers, removes remaining shives, and aligns fibers parallel for spinning or twisting.

Best Fiber Plants for Retting

Not all plants ret equally well. The following are widely available and produce excellent bast fibers:

Plant	Habitat	Harvest Season	Retting Time (water)	Fiber Quality
Stinging Nettle	Roadsides, forest edges, moist soil	Late summer/fall	5-10 days	Excellent — fine, strong
Dogbane	Fields, roadsides, dry soil	Fall after first frost	7-14 days	Excellent — silky, strong
Milkweed	Fields, disturbed ground	Fall	7-14 days	Good — coarser than dogbane
Basswood/Linden	Forests, river banks	Spring (fresh bark)	7-21 days	Good — thick, rope-grade
Willow	Streambanks, wet areas	Spring	5-14 days	Fair — best for lashing

Common Mistakes

1. Retting in drinking water. Toxic byproducts will contaminate the source for weeks.
2. Insufficient turning during dew retting. One side rots while the other stays raw.
3. Leaving stalks submerged “one more day.” Over-retting destroys fiber faster than under-retting. When in doubt, pull it out.
4. Skipping the drying step. Wet fibers stored in bundles will mold within 48 hours.
5. Using stalks harvested too early. Young green stalks have immature fibers that are short and weak regardless of retting quality.

Key Takeaways

• Retting is controlled decomposition that frees bast fibers from the woody core of plant stalks.
• Water retting (4-14 days) is faster and more controllable than dew retting (2-6 weeks). Warm water retting can produce results in 2-5 days.
• Test early and often — the gap between under-retted and over-retted can be less than a day in warm conditions.
• Never ret in or near drinking water sources.
• Post-retting processing (drying, breaking, scutching) is just as important as the ret itself. Skipping steps produces inferior cordage.
• Properly retted and processed fibers from nettle, dogbane, or basswood can produce cordage rivaling commercial twine in strength.