Flax [German version]

Table of contents

Product information
  Container transport
  Cargo securing

Risk factors and loss prevention:
Temperature Odor
Humidity/Moisture Contamination
Ventilation Mechanical influences
Biotic activity Toxicity / Hazards to health
Gases Shrinkage/Shortage
Self-heating / Spontaneous combustion Insect infestation / Diseases

Product information

Product name

German Flachs, Lein
English Flax
French Lin
Spanish Lino
Scientific Linum usitatissimum
CN/HS number * 5301 ff.

(* EU Combined Nomenclature/Harmonized System)

Product description

Flax belongs to the category fibers/fibrous materials, which are classified as follows [24]:

Plant hairs:

Cotton seed-hairs
Kapok tree fruit hairs

Stalk fibers from dicotyledonous plants (soft fibers):

Flax, ramie (fine spinnable fibers)
Hemp, jute, kenaf (coarse spinnable fibers)

Leaf fibers from monocotyledonous plants (hard fibers):

Sisal, Manila hemp, palm fibers (poor spinning characteristics)


Linden, raffia palm, willow

Basketwork material:

Coconut, rattan cane, halfa, piassava, esparto

Flax fibers are the retted bast fibers of the flax plant (Linum usitatissimum), which belongs to the Linaceae family and has been cultivated for several millennia. The ancient Egyptians made mummy wrappings from flax, while woven linen fabrics originating from Europe which date from the same period are also known.

The flax plant consists of root, stalk and branches bearing the seed capsules. Only the processable central portion of the stalk is usable for spinning purposes. This central portion is delimited by the cotyledonary node and the bottom of the branches (see Figure 1).

Before the seeds are even ripe, the flax plants are uprooted whole and placed in water (water retting), so separating the fibers from the remainder of the stalk.

A distinction is drawn between cold water retting (10 – 14 days) and hot water retting (a few days at temperatures of up to 35°C). After washing, the flax straw is usually kiln dried. The stalks are bent by intermeshing wooden boards and the fibers removed from the lignified stalks. The crude fibers are combed with hatchels to yield the long spinnable fibers, the short fibers (pluckings or tow) remaining between in the steel teeth of the comb.

Flax fibers are gray to light blond in color, very strong but at the same time also flexible. The fibers may be up to 140 cm in length, but approx. 60 cm is usual.

When a flax stalk is snapped, the flax fibers protrude from the broken ends, each fiber consisting of cells up to 5 cm in length. The sharp ends of the cells interlock and are thus suitable for producing woven linen fabrics.

The chemical composition of flax fibers, relative to dry weight, is as follows:

Cellulose 71%
Polyoses 18.5%
Pectins, pigments 6.5%
Lignin 2%
Waxes 2%

Quality / Duration of storage

Flax fibers are among the strongest of fibrous materials.

Flax quality is assessed on the basis of fiber length, fiber strength and purity.

Wet, moist or oil-stained bales must not be accepted.

Subject to compliance with the appropriate temperature and humidity/moisture conditions, duration of storage is not a limiting factor as regards transport and storage life.

Intended use

Flax is used to produce high quality textile fibers as well as sacking fabrics, dressing materials, tarpaulins, yarns and ropes. Due to their high strength, linen yarns and woven fabrics are suitable not only for bedding and table linen, but also for sewing threads, bookbinding fabrics and heavy woven fabrics (tarpaulin fabrics, sports mats), rucksack fabrics, working clothes, hospital linen and tropical clothing.

Flax nonwovens are used in the production of insulating sheets for house building.


(Click on the individual Figures to enlarge them.)

Drawing, flax

Figure 1
Drawing, flax

Figure 2
Drawing, flax

Figure 3
Photo, flax

Figure 4

Countries of origin

This Table shows only a selection of the most important countries of origin and should not be thought of as exhaustive.

Europe Belgium, Ireland, Netherlands, Romania, Russia, Hungary, Poland, France, Italy
Africa Egypt
Asia India
America USA, Argentina
Australia Australia, New Zealand

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Flax is wound in hanks or stricks and shipped as bales. Bales vary weight between 150 and 204 kg depending on country of origin. Some bales from the USA even weigh as much as 290 kg. The bales are shipped in compressed and uncompressed form, with compression not being so tight as for cotton in order to protect the fibers. The bales are strapped with steel strapping to ensure that they hold together better.

Marking of packages
Mark07.gif (2224 bytes)

Keep dry
Mark02.gif (2816 bytes)

Use no hooks
Mark04.gif (3269 bytes)

Keep away from heat
(solar radiation)

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Symbol, Class 4.2

Spontaneously combustible,
Class 4.2 IMDG Code
Symbol, Class 4.1

Fire hazard
(Flammable solids),
Class 4.1 IMDG Code
Symbol, general cargo

General cargo

Means of transport

Ship, truck, railroad

Container transport

Standard containers , subject to compliance with water content of goods and flooring.

Cargo handling

In damp weather (rain, snow), the cargo must be protected from moisture, since flax is strongly hygroscopic and readily absorbs moisture. This may lead to discoloration, decay, staining, a musty odor and rusted steel strapping.

Do not use hooks for cargo handling, since they may lead to sparking when they come into contact with the strapping. In addition, smoking is absolutely prohibited during cargo handling.

Stowage factor

2.60 – 2.83 m3/t (bales) [1]
2.37 – 3.62 m3/t (bales) [11]
2.55 – 4.53 m3/t [14]

Stowage space requirements

Cool, dry


Fiber rope, thin fiber nets

Cargo securing

The cargo is to be secured in such a way that the bales or strapping are not damaged. Undamaged strapping is essential to maintain compression of the bales during transport. If the strapping is broken, compression is diminished, which at the same time results in an increased supply of oxygen to the inside of the bales. This in turn increases the risk of combustion or feeds a fire which has already started. Bursting or chafing of steel strapping may lead to sparking and external ignition.

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Risk factors and loss prevention

RF Temperature

Flax requires particular temperature, humidity/moisture and possibly ventilation conditions (SC VI) (storage climate conditions).

Favorable travel temperature range: no lower limit – 25°C

Every hold should be equipped with means for measuring temperature. Measurements must be performed and recorded daily.

Flax must be stowed away from heat sources.

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RF Humidity/Moisture

Flax requires particular temperature, humidity/moisture and possibly ventilation conditions (SC VI) (storage climate conditions).

Designation Humidity/water content Source
Relative humidity 65% [1]
Water content 10 – 12% [1]
12% [14]
Maximum equilibrium moisture content 65% [1]

Flax behaves strongly hygroscopically (hygroscopicity). At a water content of 10%, flax is at equilibrium with 70% relative humidity. It must be protected from sea, rain and condensation water and also from high levels of relative humidity, if discoloration, staining and a musty odor are to be avoided. In the event of severe exposure, decay occurs which consequently impairs the tensile strength of the fibers.

Drawing, flax

Figure 5

Flax is less rot-resistant than cotton. In addition, it may swell by absorbing water vapor, resulting in an increase in volume of approx. 20%. An elevated water content is difficult to identify from external signs.

Moisture measurements are recommended prior to loading. Moisture-damaged bales must not be accepted.

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RF Ventilation

Flax requires particular temperature, humidity/moisture and possibly ventilation conditions (SC VI) (storage climate conditions).

If the product is loaded for shipment in a dry state, it does not have any particular ventilation requirements.

Problems arise if the product, packaging and/or ceiling/flooring are too damp. In this case, the following ventilation measures should be implemented:

Air exchange rate: 10 changes/hour (airing)

Moisture must constantly be eliminated, to reduce mold and bacterial activity.

Since flax very readily absorbs oxygen, before anybody enters the hold, it must be ventilated and a gas measurement carried out, since a shortage of oxygen may endanger life.

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RF Biotic activity

Flax displays 3rd order biotic activity.

It belongs to the class of goods in which respiration processes are suspended, but in which biochemical, microbial and other decomposition processes still proceed.

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RF Gases

Flax very readily absorbs oxygen. An oxygen shortage may therefore arise in closed holds and containers. Before anybody enters such holds, the holds must be ventilated and, if necessary, a gas measurement carried out.

An increase in CO2 and CO content indicates a cargo fire. The TLV of the hold air is 0.49 vol.%. As a result of the oxygen-rich lumen, bales often burn for weeks without being discovered.

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RF Self-heating / Spontaneous combustion

Flax has an oil content of 1 – 2% (waxes).

Flax is assigned to Class 4.1 of the IMDG Code (Flammable solids). However, its specific characteristics and negative external influences (see below) may cause it to behave like a substance from Class 4.2 (Substances liable to spontaneous combustion) of the IMDG Code or ADR.

Its high cellulose content makes flax particularly liable to catch fire through external ignition. Therefore, it must always be protected from sparks, fire, naked lights and lit cigarettes. Smoking is absolutely prohibited. Sparks may arise from bursting or chafing of the steel straps (and also as a result of inadequate cargo securing in the hold or container) and cause a cargo fire. In accordance with the IMDG Code, ventilation openings leading into the hold should be provided with spark-proof wire cloth.

Spontaneous combustion may occur as a result of exposure to moisture, animal and vegetable fats/oils, oil-bearing seeds/fruits, copra and raw wool. As a result of the very well developed oxygen-rich lumen of the flax fiber and the oxygen supply contained in the capillary cavity system, smoldering fires inside the bales often last for weeks.

Fire-fighting is best performed using CO2 . It is very difficult to extinguish a fire because of the excess of oxygen in the flax fiber, which maintains the fire from the inside. When fighting a fire, do not break the steel straps or open the bales, since relieving the compression increases the oxygen supply and makes it impossible to fight the fire effectively.

Water must not be used for fire-fighting, since the swelling capacity of the flax fibers (20% increase in volume) may cause damage to the hold or container walls.

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RF Odor

Active behavior Flax has a slight, unpleasant odor. A conspicuous musty odor indicates mold growth inside the bales.
Passive behavior Flax is sensitive to unpleasant or pungent odors.

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RF Contamination

Active behavior Flax does not cause contamination.
Passive behavior Flax is sensitive to contamination by dust, dirt, fats/oils and rust as well as oil-containing goods, such as oil-bearing seeds/fruits, copra, raw wool etc., since oil-impregnated fibers promote self-heating/cargo fire. Increased contamination of flax provides microorganisms with an excellent nutrient medium, which means that holds or containers must be suitably clean and in a thoroughly hygienic condition. Residues from previous cargoes, such as ores, stones, coal, metal filings, fertilizers etc., result in  losses. Rust contamination may be caused by rusty steel straps or wires, among other things. Since rust hampers the spinning process, this represents a reduction in value.

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RF Mechanical influences

Care must be taken to ensure that mechanical influences do not cause damage to strapping, which increases the risk of fire by relieving the compression of the bale and allowing a greater supply of oxygen. Use no hooks.

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RF Toxicity / Hazards to health

Since flax is highly oxygen-absorbent, a life-threatening shortage of oxygen may arise in the hold or container. Thus, before anybody enters the hold, it must be ventilated and, if necessary, a gas measurement carried out. The TLV for CO2 concentration is 0.49 vol.%.

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RF Shrinkage/Shortage

Unclearly marked bales may result in losses of volume due to incorrect delivery.

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RF Insect infestation / Diseases

Insects, in particular ants and beetles, may damage the bales during storage ashore.

Flax is highly susceptible to attack by fungi and bacteria. This is why tarpaulin fabrics are provided with fungicidal and bactericidal finishes.

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