Plant

Kapok

Light seed floss from the kapok tree, commonly Ceiba pentandra.

Reviewed 2026-09-22. Evidence level: verified. Open the interactive profile.

Key figures

Fiber length: about 10 to 35 mm
Fiber diameter / wall thickness: about 20 to 43 microns / 1 to 3 microns
Cell-wall density: about 1.31 g/cm3
Surface wax: about 0.5 to 2%
Oil sorption (loose, 0.02 g/cm3): about 36 to 45 g/g

Approximate values under the stated conditions.

Overview

Production: tonnage not verified; Indonesia supplies about 85% of global kapok (share of global kapok supply, not stated in source). Main producers: Indonesia. [2]

Light seed floss from the kapok tree, commonly Ceiba pentandra. It is usually a filling material rather than a straightforward spinning fiber.

Feel and behavior

Very light, smooth and fluffy.

Where you find it

Cushion filling, insulation and specialized blends.

Source and geography

Kapok is the seed floss lining the fruit capsules of the kapok tree, Ceiba pentandra (Malvaceae), a tropical tree grown in Southeast Asia, Africa and the Americas. Unlike cotton, the fibers grow from the inner wall of the capsule and are not attached to the seeds. A review of fiber resources reports Indonesia as the dominant supplier, at roughly 85 percent of global kapok supply. Each pod yields only about 12 to 15 g of fiber, and harvesting remains largely manual.

Advantages

Kapok is extremely light and buoyant because each fiber is a hollow, wax-coated tube.
Its waxy surface sheds liquid water, so fill does not readily wick moisture.
It is a plant-based alternative to down for people who avoid animal products.
It is gathered from long-lived trees, so fiber production needs no annual tillage.

Drawbacks

Kapok compacts with use, so pillows need regular plumping and occasional top-ups.
It cannot be spun alone, which confines it mostly to fillings and minor blends.
It is flammable like other light cellulosic floss.
Hypoallergenic claims are weakly supported, since aged kapok has cross-reacted with mold and house dust allergens in skin tests.
Soaked kapok clumps, dries slowly and rarely regains full loft.

Worth knowing

When wartime supplies of kapok from the East Indies were cut off, the United States organized a national milkweed pod collection in 1944 to fill life jackets.
A 1994 case report described what its authors called the first bronchoprovocation challenge with kapok, supporting but not proving that the fiber itself can be allergenic.

Types, grades and fabrics

Types and grades

Kapok is sold mainly as loose, cleaned floss, judged by color, loft and the amount of seed and husk fragments left in it; well-cleaned floss is pale yellowish to cream, springy and free of dark specks. Beyond loose fill, kapok is sold as airlaid nonwoven batting bonded with a binder fiber, as a minority component in spun yarns blended with cotton or synthetics, and as an ingredient in insulating nonwovens and oil sorbents. Most traded kapok comes from Southeast Asia, especially Indonesia and Thailand, which are the only producers listed in FAO statistics, although Ceiba pentandra also grows in Africa and the Americas. Organic or untreated claims describe how the trees were grown and the floss cleaned, not its physical properties, and should be documented.

Fabrics and products

Kapok's main products are fillings: pillows, cushions, mattresses, duvets, toys and upholstery, and historically life jackets and buoys. Because the fibers are too short, smooth and brittle to spin alone, kapok yarns are blends in which cotton or synthetic fibers carry the load. Airlaid kapok nonwovens bonded with low-melt binder fibers serve as insulating battings for bedding and clothing. Research uses include oil sorbent pads and booms, acoustic absorbers and carbon materials made from the hollow fibers.

Buying and care

How to judge quality

Good kapok fill is light, silky and springy, with a faint sheen and no musty smell. Squeeze a handful: it should rebound rather than stay matted. Dark flecks are seed or husk debris. Compare fill weight rather than volume; unlike down, kapok has no fill-power rating, so loft claims are hard to compare across brands. Check the label for blends with polyester fiberfill, which must be declared. Pillows need a tightly woven inner casing, ideally zippered for adjusting fill, because loose kapok is fine enough to work through open weaves. Treat hypoallergenic claims cautiously: allergy studies have found skin-test cross-reactions between aged kapok and mold and house dust extracts.

Care in detail

Most kapok pillows and cushions are not machine washable; the label governs. Remove and wash the outer cover separately. Plump the pillow daily to break up compacted fiber, and air it regularly in sunshine or a breezy, dry spot to drive out moisture. Spot clean the inner casing with a barely damp cloth and mild detergent, then let it dry completely. Do not soak the fill: wet kapok clumps and rarely regains its loft, and damp fill can grow mold. If the pillow has a zipper, tease clumps apart by hand and add fresh floss when it flattens. Keep kapok away from open flames and heaters, and store it dry in a breathable bag rather than sealed plastic.

Care at a glance

Follow the complete product’s care label. Blends, dyes, finishes and construction can change suitable washing, drying and storage.

Environmental and social footprint

Kapok comes from tall, long-lived Ceiba pentandra trees, and pod collection and floss cleaning remain largely manual. FAO production estimates cover only Indonesia and Thailand, so global volumes and farm practices are poorly documented, and no peer-reviewed cradle-to-gate life cycle assessment of kapok fill was found in this pass. The main environmental argument is substitution: kapok can replace down, which raises animal welfare questions, and polyester fiberfill, which is fossil based and sheds synthetic microfibers. Seller claims that kapok trees need no pesticides or irrigation vary by farm and were not independently verified. Worker health evidence is limited but real: a 1994 case report documented occupational asthma in a worker exposed to kapok, with a positive bronchial challenge.

Tradeoffs

Origin, processing inputs, labor, product construction and useful lifetime all need specific evidence. The name alone does not establish responsible production.

A useful question to ask: What exact material, product form and documented producer stand behind this name?

Science

Data sheet

Property	Value	Conditions	Source
Cell-wall density	about 1.31 g/cm3	cell-wall material; the hollow fiber itself is far lighter	[1]
Thermal decomposition	about 230 to 380 C	main mass loss from cellulose decomposition under inert atmosphere (thermogravimetry)	[1]
Fiber diameter	20 to 43 microns	wall thickness about 1 to 3 microns	[1]
Fiber length	10 to 35 mm		[1]
Surface wax	0.5 to 2.0 %	by mass	[2]
Thermal conductivity	0.033 to 0.040 W/m K	fiber assemblies	[2]
Oil sorption	30 to 50 g/g	times own weight, loose fiber	[2]

Cellulose-rich plant material

Seed, stem, leaf or other plant structure. Extraction and preparation vary.

Structure and chemistry

Each kapok fiber is a single lignified plant cell shaped like a thin-walled tube: diameters are about 20 to 43 microns, walls only about 1 to 3 microns thick, and lengths about 10 to 35 mm. The huge lumen gives an intra-fiber porosity of about 0.8, while the cell-wall material itself has a density of about 1.31 g/cm3. The wall contains cellulose, hemicellulose, lignin and pectin, and the surface carries a wax layer of roughly 0.5 to 2 percent that makes the fiber hydrophobic, with water contact angles of about 120 degrees.

From source to yarn

Ripe pods are collected, split and dried, and the floss is separated from seeds and husk fragments, a step still done largely by hand. Cleaned floss is baled and used loose as fill for pillows, mattresses, upholstery and life preservers. Because the fibers are short, smooth, brittle and waxy, they have low cohesion and are difficult to card and spin alone; they are normally blended with cotton or synthetic fibers, or formed into nonwovens by air-laying and thermal bonding with a binder fiber. Chemical pretreatments that remove wax are used when kapok is modified for adsorbents.

Performance in use

Kapok's value lies in low bulk density, buoyancy and insulation rather than strength; its tensile properties are low compared with bast fibers. The waxy, hollow fibers repel water yet absorb oils strongly: loose assemblies packed at about 0.02 g/cm3 have absorbed roughly 36 to 45 g of oil per g of fiber and remained usable after repeated cycles. The fiber is combustible like other cellulosics. Alkali treatment collapses the hollow tubes into flattened ribbons, destroying the properties that make kapok useful.

How it is identified

Burn tests are indicative only: kapok burns rapidly like other light cellulosic floss. Microscopy is decisive: smooth, straight, thin-walled transparent tubes with a large lumen and no convolutions, unlike cotton's twisted ribbons. FTIR shows cellulose bands together with aliphatic C-H stretching near 2917 cm-1 from plant wax and aromatic lignin bands. Kapok can be confused with milkweed floss (also hollow and waxy) and with hollow polyester fill, which melts rather than chars.

History

Timeline

1944With wartime kapok supplies cut off, the United States ran a national milkweed pod collection to fill life jackets. [5]
1994A case report documented occupational asthma in a worker exposed to kapok, confirmed by bronchial challenge. [3]
2006Laboratory work characterized kapok as a natural hollow, hydrophobic and oleophilic sorbent for oil. [4]
2010Oil sorption of kapok, milkweed and polypropylene fiber assemblies was compared under controlled packing densities. [6]

Kapok was used in upholstery and buoyant fillings before synthetic foams expanded. Its short, smooth structure has historically limited conventional spinning.

The deeper record

Kapok was long used for mattresses, cushions and buoyant life-saving equipment such as life preservers because of its lightness and water repellency. Synthetic foams and polyester fiberfill later displaced much of that market. Since the 2000s, laboratory research has revisited kapok as a renewable sorbent for oil spills, as a template for carbon materials and catalysts, and as an insulating component in nonwovens, while plantation and smallholder production remains concentrated in Southeast Asia.

Labeling and law

Regulation (EU) No 1007/2011 includes kapok among the Annex I fibre names, allowing it to be named on EU fibre-composition labels. In the US, textile products covered by the Textile Fiber Products Identification Act (15 U.S.C. 70 et seq.) and 16 CFR Part 303 disclose natural fibers by common name; stuffings and filled products may also be subject to separate rules, so the applicable regime should be checked for each product. Claims that a fill is organic or untreated require supplier documentation.

This describes what rules and standards cover. It is not legal advice; jurisdiction, product form and current rule text control.

Frequently asked

Is kapok better than down?

It depends on the use. Good down generally lofts more and recovers better after compression. Kapok is plant based, very light and supportive, but it compacts faster, needs regular plumping and cannot be washed the way down often can. Compare fill weight, casing quality and care requirements rather than assuming one is superior.

Is kapok hypoallergenic?

Not reliably. Kapok contains no animal proteins, but Thai allergy studies in the 1970s found skin-test cross-reactions between aged kapok and mold and house dust extracts, and a 1994 case report linked occupational asthma to kapok. People with dust or mold allergies should keep kapok clean, dry and encased.

Can you wash a kapok pillow?

Usually not in a machine. Soaking makes the floss clump, and it rarely recovers fully. Wash the removable cover, spot clean the inner casing, and refresh the fill by plumping it and airing it in sun and wind. Follow the maker's label if it says otherwise.

Why was kapok used in life jackets?

Each fiber is a hollow tube with a waxy, water-repellent surface, so packed kapok stays buoyant. When Southeast Asian supplies were cut off during the Second World War, the United States organized milkweed pod collection in 1944 to supply floss as a substitute.

Sources

Cite this page

Chaos. (2026). Kapok. In Fibers of Earth: An independent textile atlas. https://www.hendrickresearch.com/fibers/materials/kapok/