Fire-retardant fabric: materials, M1 standards, and selection by use
A fire-retardant fabric belongs to one of the classes M1 (non-flammable) or M2 (low flammability) under the French standard NF P 92-507. Three families dominate technical B2B curtains: inherently fire-retardant polyester, cotton or linen made fire-retardant by chemical treatment, and fire-retardant viscose. Each family has its own service life, ranging from 50 industrial washes to several hundred depending on whether the fire-retardant treatment is permanent or applied.
Within a single M1 class, two fabrics can have 10-year costs that vary by a factor of three. The difference is not visible on delivery. It shows at the first or tenth industrial wash, when the treatment disappears. Understanding the fabric material, not just its label, is the only way to buy a fire-retardant curtain that keeps its promises over the lifetime of an estate.
This article is a material guide. To understand the regulatory obligations by space, see our guide on fire-retardant curtains M1/M2 and public-access building regulations. For maintenance, see how to maintain an M1 class over time.
What is a fire-retardant fabric? Technical definition
A fabric is called fire-retardant once it has demonstrated, through a standardized test, a reduced reaction to fire. In France, the reference test is defined by the standard NF P 92-507 (February 2004) and makes the application of the M0 to M4 classification mandatory as set out in the order of 25 June 1980 in public-access buildings. The classification is not a spontaneous property of the fabric, it is the result of an electric igniter test carried out by a recognized laboratory (CSTB, LNE, IFTH).
Two mechanisms allow a textile to reach M1 or M2.
- Inherent (permanent) fire retardancy. Fire resistance is built into the fibre, either during polymerization (phosphorus atoms copolymerized into the polyester chain) or by incorporating minerals into the mass (silicates in viscose). The classification withstands washing, light and abrasion.
- Fire retardancy by treatment (applied). A chemical finish is applied to the finished fabric. Phosphate salts or nitrogen compounds modify combustion at the surface. The classification decreases with every wash that removes part of the deposit.
This distinction is invisible on the label. It changes everything about the total cost of ownership.
The three families of fire-retardant fabrics in technical curtains
Inherently fire-retardant polyester
Mass fire-retardant polyester, whose phosphorus atoms are copolymerized directly into the molecular chain of the fibre, is today the dominant material for technical B2B curtains. Several European weavers offer this type of yarn with comparable behaviour.
The fabric remains M1 (and often Euroclass B-s1, d0) throughout its service life. Industrial washes at 60 or 75 °C are tolerated without degradation of the classification, and light resistance is high (Oeko-Tex Standard 100 available from most weavers). Permanent fire-retardant polyester is not made fire-retardant, it is fire-retardant by nature, which is the major economic difference for hotels, care homes and public-access buildings receiving the public.
Preferred use cases: hotel rooms, suites, seminar rooms, restaurants, healthcare facilities, high-turnover spaces. Any configuration where the curtain will be washed during its life.
Cotton and linen made fire-retardant by chemical treatment
Cotton and linen are not naturally fire-resistant. To reach an M1 classification, they must receive a chemical finish. The two most documented families of industrial processes are treatments based on ammonium phosphate salts and treatments based on phosphonates. Both reach M1 on the finished fabric and withstand a limited number of industrial washes.
The service life of the classification varies depending on the process, the quality of application and the washing conditions. As a guide, a cotton with ammonium treatment keeps its classification for about 50 industrial washes at 75 °C, a phosphonate treatment beyond 50 depending on the weaver. Beyond that, the fabric remains usable but progressively loses the M1 guarantee, which makes it an option to avoid for a curtain subject to a contractual specification over 10 years.
Preferred use cases: decorative projects where the hand of cotton or linen is sought for the visual finish, spaces with low washing turnover (event halls, prestige offices, embassies). To avoid for public-access buildings with frequent washing.
Fire-retardant viscose, wool and specialized technical fibres
Beyond the two dominant families, several fibres reach M1 by construction. Fire-retardant viscose incorporates silicate compounds into the mass of the regenerated fibre. It offers a hand close to cotton with a permanent M1 classification. Wool is naturally difficult to ignite (keratin, moisture content, three-dimensional structure) and reaches M1 or M2 depending on the weave, without treatment.
Technical fibres such as meta-aramids, polyamide-imide and PBI exist in industrial or military curtains but remain rare in commercial fit-outs due to cost and aesthetic finish.
Preferred use cases: high-end architectural projects, spaces where a natural textile finish takes priority, environments with combined acoustic and thermal requirements (wool).
How to read a fabric's M classification
The M classification appears mandatorily on the test report (PV) issued by an approved laboratory. It cannot be inferred from the material alone.
| Class | Designation | Verified behaviour |
|---|---|---|
| M0 | Non-combustible | Does not burn, does not contribute to fire |
| M1 | Non-flammable | Does not ignite on contact with a flame |
| M2 | Low flammability | Ignites with difficulty, very limited spread |
| M3 | Medium flammability | Ignites, flame spreads moderately |
| M4 | High flammability | Rapid combustion |
For a curtain, two levels concentrate the regulatory requirements of public-access buildings: M1 for enclosed stairwells and stage curtains, M2 for escape routes and rooms over 50 m². The detail by space is covered in our guide to M1/M2 standards and public-access building regulations.
Permanent or treated: the difference over 10 years
The question is never "is this fabric M1 on the day of delivery". It is: "will this fabric still be M1 in five years, after forty washes, two staff changes and a visit from the safety commission." The answer depends entirely on the fire-retardancy method.
| Criterion | Inherently fire-retardant fabric (polyester, viscose) | Fabric made fire-retardant by chemical treatment (cotton, linen) |
|---|---|---|
| Service life of the M1 classification | The whole life of the fabric (10 to 15 years) | Variable, generally 50 industrial washes |
| Resistance to industrial washing at 75 °C | Permanent | Progressive degradation |
| Sensitivity to softeners and solvents | Low | High, can neutralize the treatment |
| Material cost per metre | Higher to buy | Lower to buy |
| Total cost over 10 years | Often lower | Often higher after replacements |
| Reliability under an inspection after 5 years | High | Variable depending on washing history |
The trade-off between permanent and treated fabric is not made on the product sheet, it is made on the expected washing history. A specification that calls for two annual washes in an industrial machine leans structurally toward inherently fire-retardant polyester. A decorative event project with no turnover may instead favour a treated cotton.
Which fire-retardant fabric for which use
The choice of a fabric is framed by three variables: the regulatory requirement of the space, the expected washing frequency, and the expected aesthetic finish.
| Use | Minimum classification | Recommended material | Why |
|---|---|---|---|
| Hotel room ≥ 50 m², suite | M2 | Inherently fire-retardant polyester | Frequent washing, estate of dozens to hundreds of rooms |
| Seminar room, restaurant | M2 | Inherently fire-retardant polyester or viscose | Heavy public traffic, frequent insurer requirements |
| Corridors, halls, circulation areas | M2 (M1 recommended) | Inherently fire-retardant polyester | Escape route, heavy light exposure |
| Enclosed stairwell, stage | M1 | Inherently fire-retardant polyester | Strict, non-negotiable requirement |
| Executive office, reception room | Variable by public-access building | Fire-retardant cotton or wool | Low washing turnover, premium decorative finish sought |
| Care home, nursery | M1 or M2 by space | Inherently fire-retardant polyester | High-frequency washing, hygiene, service life |
No material is universally superior. Mass fire-retardant polyester dominates in B2B because the public-access buildings that fit out a significant estate almost always build industrial washing into the specification. On a one-off project, a fire-retardant cotton or wool remains relevant.
How Kurtens makes a curtain to a fire-retardant specification
Kurtens designs its technical curtains to the project specification. Production capabilities cover the three families of fire-retardant fabrics described in this article, with operational priority given to inherently fire-retardant polyester for B2B orders (turnover, durability, traceability of the classification). M1 certification is available on request, with the CSTB or IFTH test report supplied for the safety register.
Technical textile options (100% blackout, measured acoustic attenuation up to 22 dB, measured thermal insulation up to 7 °C of gain) can be combined on a single fire-retardant curtain depending on the chosen configuration. The dedicated B2B team prepares the quote within 24 hours and offers a colour and material sample. No minimum order is imposed. To start a project, see the made-to-measure fire-retardant curtains page or request a B2B quote.
Frequently asked questions about fire-retardant fabric
What is the difference between an M1 fabric and a flame-free fabric?
"Flame-free fabric" is a commercial expression with no normative definition. "M1 fabric" is an official classification defined by the standard NF P 92-507: the fabric has passed an electric igniter test in an approved laboratory and did not catch fire under the defined conditions. Only the M1 (or M2) mention accompanied by a dated test report has regulatory value in public-access buildings.
How can you tell whether a fabric is permanently fire-retardant or made so by treatment?
The information appears on the weaver's technical sheet, never on the label. Ask for: composition (inherently fire-retardant polyester, fire-retardant viscose, or natural fabric with a chemical finish), fire-retardancy process, guaranteed resistance to industrial washing. The classification test report states the test conditions (before or after washes).
Can a fire-retardant fabric lose its M1 classification?
Yes, in two cases. A fabric made fire-retardant by chemical treatment loses its classification when the finish is removed by successive washes or by incompatible products (softeners, chlorinated solvents). A fabric with inherent fire retardancy keeps its classification, but a dye, coating or untested treatment can change the fire behaviour. Any modification of the fabric after the test report requires a new test.
Which colors are available on a fire-retardant fabric in B2B?
Inherently fire-retardant polyester is dyed in the mass or in a bath depending on the weaver, which allows a wide customizable palette. A specific shade not available in the weaver's catalogue can be produced as a dedicated order depending on volumes. Kurtens supplies a colour sample for validation before production starts.
Does fire-retardant fabric contain chemicals harmful to health?
Inherently fire-retardant fabrics incorporate the fire-retardant compounds into the mass of the fibre, with no diffusion. Most are certified Oeko-Tex Standard 100, guaranteeing the absence of harmful substances above defined thresholds. Applied chemical treatments (ammonium salts, phosphonates) are also Oeko-Tex for recent products. The INRS documents the safe use of these materials in commercial buildings.
Do you need a recent test report for a fire-retardant fabric to be valid in a public-access building?
The standard NF P 92-507 does not set a validity period for the test report. In practice, a test report more than 5 years old can be challenged by an inspection body or a safety commission, especially if the composition of the fabric has changed at the weaver. Always ask for a test report dated less than 5 years ago, and keep the test report in the safety register.
Regulatory note: this article presents the technical and normative principles applicable to fire-retardant fabrics. It does not replace consulting an approved inspection body or reading the order of 25 June 1980. The exact obligations by space depend on the type of public-access building and the configuration of the building.
To start a fire-retardant curtain project to specification: request a B2B quote. Response within 24 hours, volume discounts, M1 certification on request.
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