“Fire retardant” is not a specification. It is a claim that means three completely different things depending on which standard your customer is auditing against.
The three you will meet
| Standard | Where it applies | What it tests | Typical requirement |
|---|---|---|---|
| FMVSS 302 | Automotive interiors (US) | Horizontal burn rate of the material | Under 102 mm/min |
| UL94 V-2 | Electrical and electronic equipment | Vertical burn, self-extinguishing | Extinguishes within 30 s, no flaming drips that ignite cotton |
| Inherent aramid | Protective clothing, welding, firefighting | Material does not melt or support combustion | No additive to wash out; survives laundering |
Additive FR nylon
The commonest route: nylon with a flame-retardant additive in the polymer. It passes FMVSS 302 and UL94 V-2, keeps most of the hand and drape of standard tape, and costs 15–25% more. It is the right answer for automotive trim, seat covers, headliners and most electrical enclosures.
The limit: the additive is in the fibre, so it does not wash out — but it does degrade with prolonged UV and heat. For an engine bay or an outdoor installation, ask for test data on aged samples, not fresh ones.
Inherently FR: meta-aramid
Aramid does not burn because of what it is, not because of what was added. It will not melt and drip, it withstands short exposure to 260 °C, and there is no finish to launder out. This is what goes into turnout gear, welder’s blankets and firefighting hoods.
It is also roughly four to six times the price of FR nylon, harder to dye, and available in a narrower width range. Specify it because the standard demands it, not because it sounds better.
What a test report must contain
Anyone can print “FR” on a carton. A usable report names the standard, the test lab, the date, the sample construction and the result — and it is issued against the lot you received, not the one from two years ago. Ask for a per-lot report; if the answer is a generic PDF from 2019, keep asking.
Quick decision
Car interior → FR nylon, FMVSS 302. Electronic enclosure → FR nylon, UL94 V-2. Firefighter or welder → meta-aramid. Near a heat source but not in a flame path → 150 °C heat-stabilised nylon, which is a temperature problem, not a flammability one.
Need this applied to your part?
Send the substrate, the load and the drawing. We will come back with a construction, a tolerance and a sample date.
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