Fibres · Synthetic
Aramid (Kevlar / Nomex)
The armour fibre: extremely strong in tension and flame-resistant, it neither melts nor burns. It is technical, for protection and reinforcement, stiff and not at all soft: it is not meant for ordinary knitted garments, but for special uses.
Translated from Italian. A native knitter has not reviewed this translation yet.
History
It was born in the DuPont laboratories: the meta-aramid Nomex arrived in the 1960s and the para-aramid Kevlar was patented in 1965 by Stephanie Kwolek. The family was joined by European and Japanese equivalents such as Twaron and Technora, produced mainly in the United States, the Netherlands and Japan. Its field is not fashion but bulletproof vests, firefighters' suits, cut-resistant gloves, cables and composites.
How the yarn is made
It is a continuous filament made by extrusion: the polymer is dissolved and spun through a spinneret into an acid solution, then coagulated and drawn. In para-aramid the molecular chains line up almost perfectly along the fibre axis, and it is precisely this order that gives it exceptional stiffness and tenacity. It comes as continuous filament, but also cut into staple for blended yarns and technical felts.
Why it is prized
Weight for weight it is tougher than steel and withstands very high temperatures without melting: it is inherently flame-resistant, does not feed the flame and self-extinguishes. In knitwear and technical fabrics it is used where resistance to cutting, tearing and heat matters, not softness or next-to-skin comfort.
Dyeing
Hard to dye: its very compact, crystalline structure does not let dyes in easily, and para-aramid has a characteristic gold colour of its own. It is almost always used in its natural colour or mass-dyed, with the pigment added before extrusion. The golden yellow of Kevlar and the off-white of Nomex are in effect its livery.
Care
It does not fear heat or common solvents, but it has two specific enemies: ultraviolet light, which weakens it with prolonged exposure, and strong acids and chlorides. So it should be stored away from direct light. It does not felt and hardly pills, because it is smooth and has no elasticity of its own.
End of life
It is not biodegradable: it is a very stable synthetic polymer that persists in the environment for a long time. Recycling is possible but niche, mostly as ground reinforcement in composites and friction materials; recovering clean fibre from used garments and cables remains difficult and rare.
How to recognise it
| Hand | Stiff, dry and a little slippery, cool to the touch like synthetics. It has no elasticity of its own and resists bending: the yarn tends to stay straight instead of following the hand. |
|---|---|
| Look | Para-aramid has a characteristic gold colour with a slight lustre; meta-aramid is off-white and more matt. The fibre is smooth, without crimp and without halo. |
| Behaviour | It does not recover because it is not elastic, it has very little give because it is extremely stiff, it does not crease in the soft sense of the word, and it withstands very high temperatures without deforming. |
| Burn test | Unmistakable technical signature: it does not melt and does not feed the flame, it chars and self-extinguishes, leaving a brittle black residue, with a faint, sharp smell. This is the test that tells it apart from common synthetics, which melt into a bead. |
| Home tests | Burn test: it does not melt into a droplet, it chars and goes out on its own · Stiffness test: the yarn resists bending and has no elastic recovery · Colour test: para-aramid has the typical natural gold tone |
| Confused with | Polyester and nylon that imitate it in technical fabrics: but in the flame they melt into a hard bead and do not withstand heat · Glass fibre in reinforcements: but in the flame glass does not char and stays stiff and unchanged |
| Only in a lab | Telling para-aramid from meta-aramid with certainty, and identifying the exact blend of a technical fabric, requires laboratory analysis (infrared spectroscopy and tests according to ISO 1833). |
Physical facts
| Property | Value | Source |
|---|---|---|
| elastic memory | None | research |
| sag | Low (extremely stiff) | research |
| halo | None | research |
| felting risk | None | research |
| fineness (µm) | 10–15 | research |
| moisture regain (%) | 4.5–7.0 | research |
| typical shrinkage (%) | 0–1 | estimate |
| staple length (mm) | — | research |
measured = a measurement with a reference · iso = a standard · research = a verified source · estimate = plausibility only
Good for
cut-resistant reinforcements and inserts · technical and protective fabrics · flame-resistant workwear · blended yarns where toughness is needed
Less good for
soft next-to-skin knitwear · stretchy garments and ribs that must spring back · fluid drape · a beginner's first project