What are fire-resistant clothes made of, and does FR clothing really work? Treated cotton, inherent blends and the tests behind the label
FR clothing is made of fabrics that self-extinguish when the flame is removed and do not melt or drip, and there are two ways to get there: treated fabrics, usually cotton or a cotton-nylon blend with a flame-retardant chemistry bonded into the fiber, and inherent fabrics, where the fiber itself will not sustain a flame (aramids such as Nomex and Kevlar, modacrylic, and blends of them with cotton or rayon). MCR Safety states the fabric on every FR garment page: its Tingley FR line is 100 percent cotton in 6.5 to 13 oz weights or an 88/12 cotton-nylon twill (treated), its Summit Breeze line is a 5.5 oz inherent blend or a 7 oz cotton, its FR hi-vis vest a modacrylic/aramid blend, and its Big Jake FR rainwear PVC on meta-aramid. It works in the sense the tests define: an NFPA 2112 garment limited predicted body burn to 50 percent or less in a 3-second instrumented-manikin flash fire (ASTM F1930), kept its char length to 4 inches or less and its afterflame to 2 seconds or less in the vertical flame test after 100 launderings, and an ASTM F1506 garment has an arc rating (ATPV) from the ASTM F1959 arc test. It does not make the wearer fireproof; it buys the seconds in which a flash fire or arc ends, and it has to be the outer layer over non-melting underlayers to do it.
MCR Safety Tingley FR CCMG FR Coveralls, ATPV 8.7 cal/cm², CAT 27 oz treated cotton, NFPA 2112 and ASTM F1506, as MCR Safety lists it (MCR Safety data)Why “fire-resistant” and “fireproof” are different claims. Ordinary cotton ignites and keeps burning after the flame is gone; polyester and nylon melt onto the skin. An FR fabric chars where the flame touches it and stops burning when the source is removed, and the certification tests measure exactly that and nothing more. NFPA 2112 puts the finished garment on a manikin with more than a hundred heat sensors inside a 3-second propane fire and counts the sensors that record a second- or third-degree burn; 50 percent or less is a pass. ASTM F1959 exposes fabric panels to an electric arc and finds the incident energy at which heat through the fabric reaches the burn threshold half the time; that is the ATPV in cal/cm². Treated and inherent fabrics both pass; the difference is how the flame resistance got into the fiber and how it holds up to laundering, which the standards also test (2112 requires the flame test after 100 wash cycles).
The two ways a fabric becomes FR
And the fabrics MCR Safety lists on its garments.
Does it really work: what the tests measure, and what they do not
- NFPA 2112: 3-second flash fire on an instrumented manikin, 50 percent or less predicted body burn; vertical flame test with char length 4 inches or less and afterflame 2 seconds or less after 100 launderings; heat transfer, thermal shrinkage and thread, label and closure tests. MCR Safety lists ASTM F1930 on most of its NFPA 2112 garments.
- ASTM F1506 and F1959: the garment fabric is arc-tested and the ATPV printed; MCR Safety states 8.6 to 21.2 cal/cm² on its line, CAT 2 (8 cal/cm² minimum) on nearly every garment and CAT 1 on the hi-vis vest.
- What the tests do not cover: exposures longer than the test, molten metal splash (a separate standard), chemical splash, and a garment worn over a melting base layer; NFPA 70E 130.7(C)(12) prohibits meltable fabrics such as acetate, nylon, polyester and polypropylene next to the skin under arc-rated clothing unless they are themselves arc-rated.
- Laundering: treated and inherent garments both keep their rating through the laundering their maker specifies; the 100-wash flame test in NFPA 2112 is the check. MCR Safety’s care statement is on each product page.
- UL certification: the mark MCR Safety lists on its Tingley FR and Summit Breeze garments, meaning a third party verified the NFPA 2112 claim.
Portwest’s FR fabrics
Portwest names its FR fabrics on each page: Portwest Bizflame 88/12 is an 88% cotton, 12% nylon twill (7 oz, ATPV 8.2 cal/cm²); Portwest Bizflame Work and Portwest Bizweld Work are 100% cotton (9.5 oz, 11.2 to 13.6 cal/cm²); Portwest Bizflame Knit is a 99% cotton, 1% carbon-fiber knit for T-shirts, henleys and sweatshirts (10 to 24 cal/cm²); Portwest Modaflame Knit is 60% modacrylic, 39% cotton, 1% carbon fiber (9 to 22 cal/cm²), an inherent blend; and the IFR IKBJ pieces are Kermel aramid and FR rayon (33 cal/cm²). The group below carries those pieces with the figures Portwest states.
Portwest product pages and US data sheets for the styles shown (documents.portwest.com), fetched Nov 7 2026The FR fabrics Neese and Radians name
Radians describes its VolCore and Neese FR workwear as self-extinguishing and non-melting when exposed to flame. The fabrics on this site are the ones the product pages name: 4.5 oz Nomex (CAT 1, 4.6 cal/cm² on the Neese bib pants), 7 and 9 oz Indura and 7 and 8 oz Ultra-Soft 88/12 cotton-nylon (CAT 2, 8 to 11.5 cal/cm²), 5.5 oz Westex DH (CAT 1, 6.6 to 6.8 cal/cm² on the Radians FR vests) and 5.7 oz Westex DH Air (CAT 2, 8 cal/cm²), 100 percent cotton FR sateen and cotton-nylon twill on the Radians VolCore line (CAT 2, 8.9 to 11 cal/cm²), modacrylic blends (CAT 1 at 5.1 to 5.4 cal/cm² on the vests, CAT 2 at 8.6 to 9.6 on the shirts and coveralls, and CAT 4 at 52 cal/cm² on the Neese VM7JBL3 insulated jacket) and 9.6 oz Polartec Power Grid FR fleece (20 cal/cm² on the Neese balaclava). Each page lists the standards Radians prints: NFPA 2112, NFPA 70E, ASTM F1506 and UL certification where they apply, with ANSI/ISEA 107 Type R Class 2 or 3 on the hi-vis FR shirts and vests. Radians’ heated gear is listed as not FR rated; its self-extinguishing (SE) vests are ASTM D6413 only, with no arc rating.
Neese and Radians VolCore product pages and the Radians FR workwear page (radians.com, radians.com, fetched Nov 8 2026)Neese and Radians FR fabrics on this site, with the arc rating and category each page prints
| Fabric | Weight | Arc rating | Category | Standards listed |
|---|---|---|---|---|
| Nomex (Neese) | 4.5 oz | 4.6 cal/cm² | CAT 1 | NFPA 70E; UL certified |
| Indura treated cotton (Neese) | 7 oz and 9 oz | 8 to 11.5 cal/cm² | CAT 2 | NFPA 70E; UL certified; NFPA 2112 on the shirt |
| Ultra-Soft 88/12 cotton-nylon (Neese) | 7 oz and 8 oz | 8.5 to 9.87 cal/cm² | CAT 2 | NFPA 70E; UL certified |
| Westex DH (Radians FR vests) | 5.5 oz | 6.6 to 6.8 cal/cm² | CAT 1 | NFPA 70E; NFPA 2112 and UL certified where printed; ANSI/ISEA 107 Class 2 or 3 |
| Westex DH Air (Neese shirt, Radians vests) | 5.7 oz | 8 cal/cm² | CAT 2 | NFPA 2112; NFPA 70E; UL certified; ANSI/ISEA 107 Class 2 or 3 |
| 100% cotton FR sateen and 88/12 twill (Radians VolCore) | 6.5 to 9 oz | 8.9 to 11 cal/cm² | CAT 2 | NFPA 2112; NFPA 70E; ASTM F1506; UL certified |
| Modacrylic blends (Radians, Neese) | 5.8 to 7.75 oz | 5.1 to 9.6 cal/cm² | CAT 1 or 2 | NFPA 70E; ASTM F1506; ANSI/ISEA 107; NFPA 2112 on the Neese coverall |
| Polartec Power Grid FR fleece (Neese balaclava) | 9.6 oz | 20 cal/cm² | CAT 2 | ASTM F1506; NFPA 70E; NFPA 2112 |
| Neese VM7JBL3 insulated hi-vis jacket, 7 oz modacrylic | 7 oz | 52 cal/cm² | CAT 4 | NFPA 2112; NFPA 70E; ASTM F1506; UL certified; ANSI/ISEA 107 Class 3 |
Source: The Neese and Radians product pages on radians.com, fetched Nov 8 2026; the Arc Rating, Arc PPE Category, Material and Standards lines on each product page on this site. Radians prints ATPV figures only; the garment label governs.
More questions people ask
What fabrics are fire-resistant?
Either treated fabrics (cotton or cotton-nylon with a flame-retardant chemistry bonded in) or inherent fabrics (aramid, modacrylic, FR rayon blends). MCR Safety states which on every garment page: 100 percent cotton, 88/12 cotton-nylon, a 5.5 oz inherent blend, modacrylic/aramid, or PVC on meta-aramid for rainwear.
What material will not burn, which fabrics are the most and least flammable, and why do welders wear 100 percent cotton?
No clothing fabric is fireproof; the FR fabrics char and self-extinguish when the flame is removed, which is the claim the tests measure. The fibers that do that on their own are the aramids (Nomex, Kevlar), modacrylic, FR rayon and wool to a degree; treated cotton and cotton-nylon blends do it because of a chemistry bonded into the fiber. The most flammable common fabrics are untreated cotton and linen (they ignite and keep burning) and the lightweight synthetics, polyester, nylon, acrylic, polypropylene and spandex, which melt and drip onto the skin, the behavior 1910.269(l)(8)(iii) prohibits next to an arc; a cotton-polyester blend does both. Welders wear 100 percent cotton or leather over it because cotton does not melt and a heavy cotton chars slowly against spatter, while a polyester shirt melts into the burn; untreated cotton is still flammable and is not FR, which is why the FR cotton welding jackets and the live welding jacket guide exist. “Unhealthiest fabric” is not a safety question the standards answer; what the arc and flash-fire rules care about is melting and burning.
What are the disadvantages of Nomex, and what is the difference between Nomex and FR?
Nomex is a brand of meta-aramid fiber, one of the inherently flame-resistant fibers; “FR” is the property, so Nomex is one kind of FR and not a separate class. Its advantages are that the flame resistance is in the fiber and cannot wash out, and that a light fabric reaches a given arc rating (Portwest’s 6 oz Nomex Essential coverall is ATPV 6 cal/cm²; Neese’s 4.5 oz Nomex trouser is Category 1). Its disadvantages, as the product data and the fabric names show: cost (it is the expensive end of the FR lines), a lower arc rating per ounce than the heavier treated cottons at the same weight class, a hand that is less cotton-like, poor UV color fastness (Nomex fades), and, for a pure meta-aramid, the fabric can break open (EBT) in an arc rather than char through, which is why many aramid garments are blends. Modacrylic blends are the other inherent family and are blended with cotton or aramid for the same reasons.
Answers from the sources named above and in the byline.What fabrics are fire-resistant?
Two families, both tested to the same standards after laundering. Treated fabrics are cotton or cotton-nylon blends with a flame-retardant chemistry bonded into the cellulose, which is what the 100-wash vertical flame test in NFPA 2112 checks stays put: MCR Safety’s Tingley FR line is 100 percent cotton in 6.5 to 13 oz weights or an 88/12 cotton-nylon twill. Inherent fabrics are spun from fibers whose polymer chars rather than burns, aramids (Nomex, Kevlar) and modacrylic and their blends with cotton or rayon, and need no finish: MCR Safety’s 5.5 oz Summit Breeze blend, its modacrylic/aramid FR hi-vis vest and the meta-aramid under the PVC of its Big Jake rainwear. Untreated cotton ignites and keeps burning, and polyester and nylon melt; neither is fire-resistant, and that is why NFPA 70E allows plain cotton under FR clothing only as a non-melting layer. The standards do not rank the two families; the arc rating (ATPV 8.6 to 21.2 cal/cm² across MCR Safety’s line) and the NFPA 2112 certification mark are what the employer compares.
NFPA 2112 (as the garment pages state the certification); ASTM F1506 and F1959 (as the garment pages state the ATPV); NFPA 70E 130.7(C)(9); MCR Safety product pages and specification sheets for the styles shown, fetched Nov 9 2026Questions people ask
What are fire-resistant clothes made of?
Either treated fabrics (cotton or cotton-nylon with a flame-retardant chemistry bonded in) or inherent fabrics (aramid, modacrylic, FR rayon blends). MCR Safety states which on every garment page: 100 percent cotton, 88/12 cotton-nylon, a 5.5 oz inherent blend, modacrylic/aramid, or PVC on meta-aramid for rainwear.
Does FR clothing really work?
In the terms the tests define, yes: an NFPA 2112 garment held predicted body burn to 50 percent or less in a 3-second flash fire, and an ASTM F1506 garment has a measured arc rating. It is not fireproof, and it works only as the outer layer over non-melting clothing.
Is treated cotton as good as inherent?
Both pass the same tests and both keep their rating through the laundering the maker specifies. The standards do not rank them; the ATPV and the NFPA 2112 listing on the garment are what the employer compares.
What should an FR clothing seller show you?
The manufacturer’s fabric, ATPV, category and certifications on the page, so the garment can be matched to the label on the equipment or the site’s FR specification. Every MCR Safety FR page here lists them, with the price and size list.
What does CAT 2 mean on an FR shirt?
That its arc rating meets the NFPA 70E Category 2 minimum of 8 cal/cm²; MCR Safety’s CAT 2 garments run 8.6 to 21.2 cal/cm². Category 3 needs 25 and Category 4 needs 40, usually in layers or a suit.
What fabrics are fire-resistant?
Treated cotton and cotton-nylon blends (a flame-retardant chemistry bonded into the fiber) and inherent fibers that will not sustain a flame: aramids such as Nomex and Kevlar, modacrylic, and their blends with cotton or rayon. Portwest states the fiber content on each FR page (Bizflame 88/12 cotton-nylon, treated cotton, Modaflame modacrylic blends); what makes the fabric FR for the buyer is the standard on the label, NFPA 2112 or ASTM F1506.
Is FR clothing 100% cotton?
Some is: treated 100 percent cotton in 6.5 to 13 oz weights is one of the two main FR fabric types, along with cotton-nylon 88/12 twills and the inherent modacrylic and aramid blends. Plain cotton without the treatment is not FR.
What is category 3 protective clothing?
Arc-rated clothing with a minimum arc rating of 25 cal/cm² under NFPA 70E: an arc flash suit (jacket and pants or coverall) with a suit hood, arc-rated gloves, hard hat, safety glasses, hearing protection and leather footwear. The fabric behind it is the same treated or inherent FR fabric, in heavier weights or several tested layers, with the ATPV on the label.
Is 100 percent cotton considered FR?
Only when treated: untreated cotton ignites and keeps burning, which is why NFPA 70E permits it under FR clothing as a non-melting layer but not as the FR layer. MCR Safety’s 100 percent cotton FR garments carry the flame-retardant treatment and the NFPA 2112 and ASTM F1506 listings that prove it; “100% cotton” on an ordinary shirt label proves nothing about flame resistance.
What fabric is most flame resistant?
The standards do not rank fabrics; they pass or fail the same tests after laundering, and the arc rating is the measured figure. On MCR Safety’s line the ATPVs run from 8.6 cal/cm² (7 oz cotton shirts) to 21.2 cal/cm² (11.5 oz hooded sweatshirts), which is weight as much as fiber; inherent aramids keep their property for the life of the fiber, treated cotton for the launderings its manufacturer specifies.
Is FR-rated clothing made of inherent fiber or treated cotton, and how is it made?
Both are sold. Treated cotton is woven, then run through a flame-retardant finish that bonds to the cellulose (the 100-wash flame test in NFPA 2112 checks that it stays); inherent fabrics are spun from fibers whose polymer chars rather than burns (aramid, modacrylic) and need no finish. MCR Safety states which on every FR page, with the weight and the certifications.
What material will not burn in fire?
No clothing fabric is fireproof; FR fabrics char and self-extinguish. Aramids (Nomex, Kevlar), modacrylic and FR rayon do it by nature; treated cotton and 88/12 blends by a bonded finish. Untreated cotton burns; polyester and nylon melt.
What makes something flame resistant?
Either the fiber chemistry (aramid, modacrylic, FR rayon) or a flame-retardant chemistry bonded into cotton during finishing, verified by vertical flame tests (ASTM D6413) after laundering and, for garments, the NFPA 2112 manikin test and the ASTM F1959 arc test.
What are the common flame retardant chemicals used in textiles?
The treated-cotton finishes are phosphorus-based chemistries bonded into the cellulose (the trade names on the pages are the mills’: Westex UltraSoft and Indura, Proban); the manufacturers do not publish formulas, and inherent fibers use no added chemical.
What are the disadvantages of Nomex?
Cost, a lower arc rating per ounce than heavier treated cottons, a less cotton-like hand, fading in UV, and for pure meta-aramid a tendency to break open rather than char in an arc, which is why many aramid garments are blends.
Is 100 percent cotton flammable or fire-resistant?
Untreated cotton is flammable: it ignites and keeps burning. It does not melt, which is why welders wear it, but it is not FR unless treated and labeled; FR-treated 100 percent cotton garments carry the standards on the label.
Why do welders wear 100 percent cotton shirts?
Cotton does not melt onto the skin as polyester and nylon do, and a heavy cotton chars slowly against spatter. It is still flammable, which is why FR cotton and leather welding jackets exist.
Can you wear 100 percent cotton while welding?
Cotton is the minimum the trade uses because it does not melt; FR cotton or leather over it is what the hazard assessment under 1910.252(b)(3) and 1910.132 usually calls for.
What is modacrylic fiber made of, and what does it feel like?
A synthetic fiber (a modified acrylic copolymer) that is inherently flame resistant; blended with cotton or aramid it gives a soft, knit-like hand, which is why the lightweight inherent FR shirts use it.
How much does Nomex cost compared with FR cotton?
The Nomex and aramid garments are the highest-priced FR work garments on this site, and the treated FR cotton and 88/12 garments the lowest; the product list on the FR cost guide shows current prices.
The ratings, test results and standards shown here are the manufacturers' published values, reproduced as published. Nothing on this page is a recommendation by Bayshore Safety that any product is suitable for a particular task, hazard or workplace. Selecting safety products and protective equipment is the responsibility of the end user and the employer, based on their own hazard assessment and the regulations that apply to their work. Confirm every value on the manufacturer's own documentation before use.