Selecting the Most Appropriate FR Fabric and/or Fibre


Selection of the 'perfect' FR fabric and/or fibre is a complex process. Each FR fabric or fibre has particular properties which either provides benefits or shortcomings. Fabric manufacturers blend fibres in an attempt to balance these individual properties to maximise fabric performance. It is important that Corporations be aware of each fibre’s properties to ensure that garments selected meet the specific requirements of a given application.

When reviewing fabrics and fibres, Corporations should consider thermal protection, static resistance, comfort, durability, stability, employee acceptance and appearance, ease of care and maintenance, colour availability and initial and ongoing cost. There also needs to be recognition of special hazards such as electric arc, flash fire and molten metal and chemical splash. These particular hazards may require additional evaluation and/or PPC program investment to ensure employees are provided with the correct and hopefully 'perfect' protection.

Corporations should follow three basic steps when undertaking proper evaluation of different FR fabric types. They are;

  1. Identify the potential hazard - different hazards have different characteristics, which is why test results do not directly correlate to each other. Test results for electric arc flash should not be substituted for test results for flash fire.

  2. Identify industry consensus standards for the exposure - for example, NFPA 70E and ASTM F1959 and F1506 have been developed for electric arc flash environments while NFPA 2112 and ASTM F1930 have been developed for flash fire environments.

  3. Ensure testing has been conducted at independent laboratories - this will ensure that scientifically valid data is being assessed. There is no substitute for information generated at an independent laboratory. The leading independent testing laboratories for electric arc flash performance are Kinectrics and KEMA Powertest and for flash fire performance, the University of Alberta.


About Aramid Fibres

Aramid fibres (meta-aramid and para-aramid) are man-made high-performance fibres with molecules characterised by relatively rigid polymer chains. These molecules are linked by strong hydrogen bonds that transfer mechanical stress very efficiently, making it possible to use chains of relatively low molecular weight. The term aramid is short for 'aromatic polyamide'. Aromatic polyamides were first applied commercially as meta-aramid fibres in the 1960s, with para-aramid fibres being developed in the 1960s and 1970s. The first commercial aromatic polyamide was produced by DuPont™ and branded Nomex®. Thanks to its strength and heat resistance combined with tactile characteristics that were close to normal textiles, Nomex® was quickly adopted for a number of uses including protective apparel, insulation and more.

In addition to Nomex®, other world leading brands of aramid fibres include DuPont™ Kevlar®, Kermel®, Teijinconex®, Twaron® and Technora®. 

Aramid fibres are renowned for their high tensile strength. Aside from their resistance to abrasion and piercing, they also have high resistance to organic solvents and fire. They have no melting point and only begin to degrade at extremely high temperatures. They also have low flammability.

  • Nomex® starts to decompose at around 350° C. While not being as strong as Kevlar® and para-aramid variants, Nomex® has excellent thermal, chemical and radiation resistance that makes it a popular fibre for protective firefighter apparel and hazardous material clothing.

  • Kevlar® has outstanding strength-to-weight properties and an extremely high tolerance to heat that has made it one of the most popular aramid fibres for bulletproof vests. Kevlar® and other para-aramids do not degrade until above 500° C. These fibres also operate well in freezing temperatures and are nonconductive. 

  • Kermel® is a high technological aromatic polyamide, classified in the meta-aramid family. It is naturally non-flammable, which is a permanent characteristic thanks to its chemical structure including a high proportion of aromatic structures and combined double bonds. The fibre has a very high resistance to abrasion and a thermal conductivity twice as low as any other aramid fibre. It has excellent resistance to chemicals and acid attacks. When heated to very high temperatures, the fibre chars without melting or dripping, whilst retaining its structure and discharging very few fumes.

  • Tejinconex® is a high-performance aromatic polyamide fibre with excellent flame-proofing and heat resistance properties. Teijinconex® will not combust through exposure to direct flame or heat and it neither burns or melts, which means it cannot stick to human skin. It is an excellent thermal insulator and has outstanding chemical resistance. The fibre begins to decompose and carbonise at 400° C

  • Twaron® is a high-performance fibre and Teijin Aramid's flagship para-aramid product. It offers a unique combination of mechanical properties, chemical resistance, excellent durability and thermal stability. It is highly valued across a wide range of industries for the benefits it brings to a great many high-performance applications.

  • Technora® is a para-aramid fibre made from co-polymers. It was independently developed by Teijin and has been commercially available since 1987. Technora® has a range of unmatched performance properties: high tensile strength - weight for weight Technora® is eight times stronger than steel; good fatigue resistance; long-term dimensional stability; excellent resistance to corrosion, heat, chemicals and saltwater.

Aramid fibres share some general characteristics that distinguish them from other synthetic fibres, namely:

  • High strength.

  • Good resistance to abrasion.

  • Resistance to absorption.

  • Resistance to organic solvents and good chemical resistance.

  • No conductivity.

  • Low flammability with a high Limiting Oxygen Index (LOI) - Nomex® and Kevlar® 30, Kermel® 32, Teijinconex® 30, Twaron® 29 and Technora® 25.

  • No melting point.

  • Superior fabric integrity at elevated temperatures. 

  • Good cut resistance.

These unique characteristics derive from the combination of having stiff polymer molecules with strong crystal orientation as well as close interaction between the polymer chains due to the hydrogen bonds. The hydrogen bonds are aligned, for the most part, along the fibre axis, which gives them remarkable strength and flexibility.

When considering PPE for military, fire departments or the police, their personnel require the highest levels of protection, as well as comfort and wearability. They need superior thermal protection and flame resistance and resistance to tears and abrasions. What's more, they want comfort that comes with lighter weight materials, greater flexibility and increased breathability. Firefighter turnout gear made from aramid fibres meet ever-more stringent requirements in terms of protection, thermal insulation and wearing comfort. The wearer is not only protected against heat and flame, but also against hazards associated with electric arc and flash fire.

Police and Special Forces also face increasingly threatening or violent situations. Aramid fibres provide protection, not only against heat and flame but also against bullets, slashing and stabbing.

In short, aramid fibres provide the key benefits of inherent flame resistance, superior heat insulation, dimensional stability, no burning, melting or adherence to human skin and are strong, light, durable and comfortable.  


Key Determinants for Blended Fabrics

  • A blend is a fabric or yarn made up of more than one type of fibre. Blending is the combining or mixing of different fibres to achieve a desired characteristic. Blending can influence performance, colouring, strength, softness, moisture absorbency, ease of washing, resistance to wrinkling, ease of spinning and cost.

  • Blending achieves - 

    • Improvement in the quality of a fabric for meeting specific end use requirements such as performance, comfort or ease of care that would not otherwise be available in single fibres.

    • Improvement in the texture, hand or feel and appearance of the fabric.

  • When assessing PPC programs there must be a clear understanding of each fibre's characteristics, properties, advantages and disadvantages.

  • The traditional methods of manufacturing fabrics are weaving, knitting and braiding. Nonwoven fabrics are made by bonding or interlocking fibres or filaments by mechanical, thermal, chemical or solvent means. 

  • The individual yet combined properties of the blend and finished weight of the fabric will determine a specific end use, for example, the fabric’s ability to shed hot metal, the arc tested ATPV rating, the level of flash fire compliance and other types of protection, such as for welding and cutting and resistance to chemical splash/penetration.

  • Care programs must be instituted to ensure that optimum levels of protection are correctly maintained. Correct care procedures must be strictly adhered to since the thermal protective properties of any FR fabric can be compromised by the presence of contaminants on the fabric. Care and maintenance procedures should be based on the requirements of the fabric’s most sophisticated fibre.

To widen the specification of high-performance FR fabrics, principal or lead fibres such as Nomex®, FR Cotton, Kermel® and Kanecaron/Protex®, are often blended with one or a number of other high-performance fibres such as:

  • Anti-static - for electrostatic dissipation.

  • Aramid - for increased strength.

  • Kevlar® - for increased reinforcement.

  • Lycra® - for shape retention and comfort.

  • Lyocell - for high absorbency and heat capacity and softness to hand.

  • Nylon - for increased abrasion resistance.

  • Viloft® - for additional thermal properties.

  • Viscose® - for uniformity in dyeing.

  • Wool - for increased durability.

Some of the world's leading and technically blended FR apparel fabrics, used in the construction of the ArcFlashWear premium range, include:

  • E. I. du Pont de Nemours and Company (USA) - Nomex® blends, Nomex® IIIA, Nomex® MHP and DuPont™ Omega™ FR Hi Vis.

  • Bruck Textiles (Australia) - PR97™.

  • Kermel® (France) - Kermel® V50 and Kermel® V70.

  • Kaneka Corporation (Japan) - Kanecaron Modacrylic/Protex®.

  • Polartec® LLC (USA) - Polartec® FR Fleeces.

  • Westex® by Milliken (USA) - UltraSoft®, UltraSoft® AC and UltraSoft® and TrueComfort™ knits.


ArcFlashWear Fabrics and Fibres

To assist with fabric and fibre selection, the following segments provide an overview of the fibre blends and fabric compositions used to construct the ArcFlashWear premium FR Range.

Fire Rated Sock (Knitted Wool / Nylon / Wool Layers)

Merino Wool (70%) - Merino is the world’s finest wool – it is a unique fibre which looks, feels and wears like no other. It boasts a superior range of natural qualities that extend far beyond its softness next to the skin. Very slow to burn even in contact with flame; excellent moisture regain; excellent static resistance; soft and comfortable; natural elasticity; breathable and easy to care for; LOI* 25 to 26.

Nylon (30%) - key properties include toughness and resistance to abrasion, oil and solvents; high tensile strength and thermal stability; the fibre is flexible and durable with a low coefficient of friction; creep and fire resistant with excellent elasticity; easy to launder, dries quickly and retains its shape; heat and chemical resistant; Nylon Grade 6,6 (in preference to Nylon Grade 6) is more widely used for FR apparel due to its ductility (the ability to be deformed without losing toughness) and higher tensile strength; LOI* Nylon 6: 20 to 24; Nylon 6,6: 24 to 29.


PR97™ Apparel (Twill Weave)

Merino Wool - Merino is the world’s finest wool – it is a unique fibre which looks, feels and wears like no other. It boasts a superior range of natural qualities that extend far beyond its softness next to the skin. Very slow to burn even in contact with flame; excellent moisture regain; excellent static resistance; soft and comfortable; natural elasticity; breathable and easy to care for; LOI* 25 to 26.

Lenzing FR® (FR Viscose) - is a special natural viscose fibre with unique thermal insulation and permanent flame resistance properties that help prevent heat stress and heat stroke. The fibre exhibits excellent moisture regain resulting in low static propensity; acts as a natural insulator with excellent resistance to most thermal hazards: fire, radiant heat, electric arc, flash fire and molten metal splash; a flame retardant substance is incorporated throughout the cross section of the fibre which cannot be removed by either washing or abrasion; the perfect blend partner - common Lenzing FR® blends include other high-performance fibres such as Kermel®, Wool, Dupont™ Nomex®/Kevlar®; LOI* 28.


UltraSoft® Apparel (Twill Weave and Interlock Knit)

Durable FR Cotton (88%) - non-allergenic natural fibre and insulator; soft hand and easily blended with other high performance fibres; comfortable with high absorbency rate holding up to 27 times its own weight in water; strength and absorbency makes it an ideal FR apparel blend partner; the FR portion of the fabric is a long-chain polymer engineered in situ and locked in the core of the cotton fibre; the FR mechanism is solid-phase; or:

Durable FR Pima Cotton (88%) - in addition to the above, Pima Cotton, also called extra-long staple (ELS), is a type of Cotton grown primarily in Peru, USA and Australia. It is considered to be one of the superior blends of Cotton and is extremely soft, durable and absorbent.

High Tenacity Nylon (12%) - improves abrasion resistance; high tensile strength and thermal stability; the fibre is flexible and durable with a low coefficient of friction; creep and fire resistant with excellent elasticity; easy to launder, dries quickly and retains its shape; heat and chemical resistant; during a thermal exposure the nylon component is absorbed by the cotton fibre, avoiding contact with the skin; Nylon Grade 6,6 (in preference to Nylon Grade 6) is more widely used for FR apparel due to its ductility (the ability to be deformed without losing toughness) and higher tensile strength; LOI* Nylon 6: 20 to 24; Nylon 6,6: 24 to 29.


ArcWear™ Omega™ Protective Outerwear (Trilaminate System)

DuPont™ Omega™ FR Hi Vis/Nomex® IIIA (Outer Shell) - high (turnout type) tensile strength DuPont™ Omega™ FR High Visibility/Nomex® IIIA trilaminate fabric; excellent resistance to flame, heat, electric arc and hydrocarbon flash fire; inherently FR, breathable and will not melt, drip, break-open or support combustion in air; Omega™ FR offers excellent fluorescent high visibility conspicuity; exceptionally high LOI*.

DuPont™ ePTFE/PU (Moisture Barrier) - Expanded Polytetrafluoroethylene (ePTFE) offers a unique blend of high temperature resistance with a low coefficient of friction; a highly flame resistant, impermeable barrier; will not melt, drip, ignite or break-open; known for its chemical inertness, excellent dielectric stability and resistance to abrasion, chemicals, weather and ultraviolet; exceptional optical properties, negligible moisture absorption and outstanding performance at temperature extremes; LOI* >95.  

Nomex® Jersey Knit (Inner Layer) - provides an internal, comfortable thermal protective layer; Nomex® Jersey Knit nonwovens combined with Nomex® fibre and filament face cloths provide durable, flexible, breathable and heat-insulating components; multi-layer Nomex® based thermal liners are among the thinnest, most flexible and breathable available.


ArcWear™ MP3 Protective Outerwear (Trilaminate System)

DuPont™ Nomex® IIIA (Outer Shell) - a blend of Nomex® (93%), Kevlar® (5%) and P-140, a permanent carbon core polyamide electrostatic dissipative fibre (2%); the blend is inherently FR, has excellent tensile strength, is lightweight and breathable and will not melt and drip or support combustion in air; LOI* 30 (for individual properties of Nomex®, Kevlar® and P-140, refer ArcWear™ Nomex® IIIA Fleece Jacket/Liner).

DuPont™ ePTFE (Moisture Barrier) - Expanded Polytetrafluoroethylene (ePTFE) composite film on Nomex® E89™ offers a unique blend of high temperature resistance with a low coefficient of friction; a highly flame resistant, impermeable barrier; will not melt, drip, ignite or break-open; known for its chemical inertness, excellent dielectric stability and resistance to abrasion, chemicals, weather and ultraviolet; exceptional optical properties, negligible moisture absorption and outstanding performance at temperature extremes; LOI* >95.

Nomex® Jersey Knit (Inner Layer) - provides an internal, comfortable thermal protective layer; Nomex® Jersey Knit nonwovens combined with Nomex® fibre and filament face cloths provide durable, flexible, breathable and heat-insulating components; multi-layer Nomex® based thermal liners are among the thinnest, most flexible and breathable available.


ArcWear™ Rampart FR™ Protective Outerwear (Dual Layer System)

The Rampart FR™ ExoGuard (Outer Shell) technology features an exoskeleton, electrostatic dissipative (ESD) control fibre for protection against the build-up of static electricity; soil and stain resistant; offers superior resistance to flame, heat, electric arc and hydrocarbon flash fire; inherently FR, waterproof, windproof, breathable and will not melt, drip, break-open or support combustion in air. ExoGuard technology offers excellent fluorescent high visibility worker conspicuity; exceptionally high LOI*.

Breathable Urethane Composite (PU Moisture Barrier) is a unique material that offers the elasticity of rubber combined with the toughness and durability of metal; durable, flexible and will not become brittle as it ages; excellent resistance to flame, heat, electric arc and hydrocarbon flash fire; extremely durable with superior puncture, tear and abrasion resistance; waterproof, windproof and will not melt, drip, ignite or break-open.

The Polartec® Power Dry® FR (Inner Layer) provides a moisture management system, which pulls moisture directly from the skin, transferring it to the outer shell to quickly dissipate; this evaporation process helps keep the body cool as body heat increases and warm when temperatures begin to drop; inherent FR properties with superior resistance to electric arc and hydrocarbon flash fire; LOI* 28.

The individual properties of the fibres used to construct Polartec® Power Dry® FR can be viewed in the ArcWear™ Polartec® FR Hi Vis Fleece Jacket/Liner section.


ArcWear™ Nomex® IIIA Fleece Jacket/Liner (Nomex® IIIA Double Knapped Knit)

Nomex® (93%) - Nomex® is an inherently flame resistant, high-temperature resistant meta-aramid fibre that does not melt and drip or support combustion in air. A key factor in the protection provided by Nomex® is its ability to carbonise and thicken when exposed to intense heat (above approx. 427° C). This typical reaction increases the protective barrier between the heat source and the wearer’s skin and minimises burn injury; LOI* 30.

Kevlar® (5%) - Kevlar® is a man-made fibre of the aromatic polyamide (para-aramid) family. The chemical structure of para-aramids distinguishes them from other commercial man-made and natural fibres and gives Kevlar® its unique properties. It has high strength, high modulus (stiffness), toughness and thermal stability. In addition, it is resistant to many of the chemicals and solvents encountered in today’s industrial environment. This combination of properties makes it an exceptional reinforcement fibre; the fibre inhibits thermal shrinkage and helps minimise break-open; extraordinarily strong, light and cut-resistant; LOI* 28.

P-140 (2%) - a permanent carbon core polyamide electrostatic dissipative fibre ideally suited for blending with other high-performance fibres.


ArcWear™ Polartec® FR Hi Vis Fleece Jacket/Liner

Modacrylic (67%) - a high-performance fibre that has the characteristics of high flame resistance in addition to soft hand and dye ability, as is the nature of acrylic fibres; resilient, abrasion resistant, quick drying, resistant to acids and alkalis and shape retentive. It is an inherently self-extinguishing FR fibre that imparts excellent flame resistant properties to fabrics and nonwovens in blends with other natural and synthetic fibres. There is no deterioration in flame reistance after either repeated washing or normal use over time; LOI* 28-32.

Viscose Rayon (29%) - a cellulosic fibre with many properties similar to those of cotton or other natural cellulosic fibres; moisture absorbent (more so than cotton), breathable, comfortable next-to-skin softness and easily dyed in vivid colours; moderate dry strength and abrasion resistance; does not build up static electricity nor will it pill; is not resilient and therefore tends to wrinkle; withstands ironing temperatures slightly less than those of cotton. One of rayon's strengths is its versatility and ability to blend easily with many FR fibres; LOI≥ 28. 

Spandex (4%) - a synthetic fibre known for its exceptional elastic nature (10 times that of rubber) and is stronger and more durable comparatively over rubber; can be stretched repeatedly more than 500% of its original size and can also recover back immediately to its original size and shape once the tension is relaxed; lightweight, smooth and soft and provides comfort and fit to garments; does not spoil due to body odour, detergents or after multiple washes; offers scratch proof abilities.


ArcWear™ Sentinel™ Protective Outerwear (Laminate System)

FR Polyurethane - FR Polyurethane (PU) is a unique material that offers the elasticity of rubber combined with the toughness and durability of metal; durable, flexible and will not become brittle as it ages; excellent resistance to electric arc, hydrocarbon flash fire, chemical penetration and most acids, salts and alkalis; extremely durable with superior puncture, tear and abrasion resistance; wind and waterproof; will not melt, drip, ignite or break-open; offers exceptional fluorescent high visibility conspicuity.

100% FR Cotton Knit - durable, flexible, breathable and extremely heat insulating. Provides an internal, durable and comfortable thermal protective layer.


Breathable ArcWear™ Omega™, ArcWear MP3 and Rampart FR Rainwear - breathable rainwear fabrics are usually manufactured by laminating a woven Nomex® outer shell fabric to a breathable polyurethane layer system or laminating the shell fabric to a Nomex® knit or nonwoven lining with a breathable ePTFE membrane in a trilaminate system.

DuPont™, E89™, Kevlar®, Nomex®, Nomex® IIIA and Omega™ Hi Vis are registered trademarks or trademarks of E. I. du Pont de Nemours and Company or its affiliates.


Projob Hi Vis Work Wear (Heavy Duty Twill Weave)

Modacrylic Protex® (54%) - a high-performance fibre that has the characteristics of high flame resistance in addition to soft hand and dye ability, as is the nature of acrylic fibre; resilient, abrasion resistant, quick drying, resistant to acids and alkalis and shape retentive. It is an inherently self-extinguishing FR fibre that imparts excellent flame resistant properties to fabrics and nonwovens in blends with other natural and synthetic fibres. There is no deterioration in flame resistance after either repeated washing or normal use over time; LOI* 32 (35 when blended with Cotton).

Cotton (44%) - a non-allergenic natural fibre and insulator; soft hand and easily blended with other high performance fibres; comfortable with high absorbency rate holding up to 27 times its own weight in water; strength and absorbency makes it an ideal FR apparel blend partner.

Anti-static Control Fibre (2%) - a permanent carbon core polyamide electrostatic dissipative fibre ideally suited for blending with other high-performance fibres.


Projob Undergarments (Knitted Blend)

Merino Wool (50%) - Merino is the world’s finest wool – it is a unique fibre which looks, feels and wears like no other. It boasts a superior range of natural qualities that extend far beyond its softness next to the skin. Very slow to burn even in contact with flame; excellent moisture regain; excellent static resistance; soft and comfortable; natural elasticity; breathable and easy to care for; LOI* 25 to 26.

Lenzing FR® (50%) - excellent moisture regain resulting in low static propensity; acts as a natural insulator with excellent resistance to most thermal hazards: fire, radiant heat, electric arc, flash fire and molten metal splash; a flame retardant substance is incorporated throughout the cross section of the fibre which cannot be removed by either washing or abrasion; the perfect blend partner - common Lenzing FR® blends include other high performance fibres such as Kermel®, Wool, Dupont™ Nomex®/Kevlar®; LOI* 28.


Projob Sock (Knitted Blend)

Kermel® (41%) - a polyamide-imide (classified in the meta-aramid family) with excellent thermal stability. Naturally non-flammable, which is a permanent characteristic due to its chemical structure including a high proportion of aromatic structures and combined double bonds. The fire resistant properties do not dissipate over time or after washings. Kermel® provides maximum protection of several seconds against extreme temperatures (1000° C). Will not melt and drip; excellent flame, heat, chemical and abrasion resistance; soft and comfortable; inherently FR; high temperatures causes the polymer to char slowly; LOI* 32.

Lenzing FR® (41%) - is a special natural viscose fibre with unique thermal insulation and permanent flame resistance properties that help prevent heat stress and heat stroke. The fibre exhibits excellent moisture regain resulting in low static propensity; acts as a natural insulator with excellent resistance to most thermal hazards: fire, radiant heat, electric arc, flash fire and molten metal splash; a flame retardant substance is incorporated throughout the cross section of the fibre which cannot be removed by either washing or abrasion; the perfect blend partner - common Lenzing FR® blends include other high-performance fibres such as Kermel®, Wool, Dupont™ Nomex®/Kevlar®; LOI* 28.

Nylon (17%) - key properties include toughness and resistance to abrasion, oil and solvents; high tensile strength and thermal stability; the fibre is flexible and durable with a low coefficient of friction; creep and fire resistant with excellent elasticity; easy to launder, dries quickly and retains its shape; heat and chemical resistant; Nylon Grade 6,6 (in preference to Nylon Grade 6) is more widely used for FR apparel due to its ductility (the ability to be deformed without losing toughness) and higher tensile strength; LOI* Nylon 6: 20 to 24; Nylon 6,6: 24 to 29.

Lycra® (1%) - a man-made elastin fibre, always blended with other high-performance fibres; unique stretch and recovery properties and provides comfort, fit, shape retention, durability and freedom of movement; easily dyed, durable and resistant to pilling and abrasion; naturally moisture wicking pulling moisture away from the body.


*Limiting Oxygen Index (LOI)

Flame resistant ability has a direct correlation to the Limiting Oxygen Index of the fibre(s) used in a fabric's composition. The Limiting Oxygen Index is a measurement, expressed as a percentage, of the minimum concentration of oxygen needed in air to support combustion of the fibre. Since atmospheric air contains an oxygen concentration of 20.95%, fibres with a greater value Limiting Oxygen Index can be considered non-flammable or flame resistant, although it is acknowledged that a Limiting Oxygen Index ≥ 26 provides for the safest level of protection. This property prevents combustion and therefore propagation of fire to a wider environment.