Fire Suit Washing Guide: Nomex Care and Reproofing

Why Standard Laundry Destroys Nomex

Nomex (aramid fiber) fire suits maintain their flame resistance through the inherent chemistry of the fiber itself — the protection is not a surface treatment that can wash out. However, the mechanical structure of Nomex yarn is sensitive to harsh detergents, high heat, and agitation. Over-washing degrades the fiber tensile strength, and a suit that passes SFI 3.2A/5 fire testing when new may not perform identically after 50 wash cycles with standard laundry detergent.

What actually degrades Nomex in washing:

• Optical brighteners in standard detergents (UV-reactive compounds that make white clothes look whiter) — they bond to fiber surfaces and alter the UV response of the material
• Chlorine bleach — breaks down aramid polymer chains directly, causing fiber embrittlement
• High temperature drying — aramid fibers are heat-stable to ~450°C but the suit's thread, closures, and patches are not; high dryer heat shrinks seams and damages zipper tape
• Aggressive spin cycles — mechanical stress on wet Nomex causes fiber crimping

The result of repeated improper washing is a suit that looks fine but has reduced TPP (Thermal Protective Performance) relative to its rated value.

The Correct Wash Protocol

Before washing: close all zippers fully, turn the suit inside out to protect outer surfaces and patches, remove any external patches or embroidered numbers if possible.

Recommended products:

• Nikwax Tech Wash — the gold standard for technical fabrics. pH-neutral, no brighteners, no bleach
• Atsko Sport-Wash — an alternative with similar properties
• Manufacturer-branded cleaners (Alpinestars, OMP, Sparco all offer their own) — reliable but often more expensive

Wash settings:

• Machine: delicate or gentle cycle, cold or warm (max 30°C/86°F)
• Hand wash: preferred for heavily soiled areas, using the same detergent
• Avoid pre-soak with stain removers unless they are specifically labeled Nomex-safe

Stain treatment: motor oil, brake fluid, and fuel are the common contaminants. Spot-treat with a small amount of Nikwax Tech Wash applied directly, work in gently with a soft brush, then proceed with normal wash. Do NOT use WD-40 or solvent spot removers — they leave residue that reduces flame resistance at the treated area.

For heavily soiled suits after a race incident with significant fluid contamination, consider sending to a specialist cleaner. Alpinestars and other manufacturers offer cleaning services.

Drying: Temperature and Method

Tumble drying on low heat (below 60°C / 140°F) is acceptable for most fire suits per manufacturer guidelines. Check your specific suit's care label first — some multi-layer suits with quilted inner layers should not be machine dried.

Air drying is always the safest option and the recommendation if you have any doubt. Hang the suit by the shoulders on a wide hanger (not a narrow wire hanger that compresses the shoulder seam) in a well-ventilated area out of direct sunlight. UV exposure bleaches Nomex colors and degrades the outer weave structure over time.

Drying time: a three-layer suit air-dried at room temperature typically requires 4-8 hours. Ensure the inner quilted layers are fully dry before storing — trapped moisture creates conditions for mold growth, which will destroy Nomex fibers over a season.

Never iron a fire suit. The zipper tape, patches, and some lining materials will melt or scorch at ironing temperatures. If the suit is wrinkled after washing, re-hanging while damp and smoothing the seams by hand is sufficient — race suit wrinkles don't matter for protection performance.

DWR Reproofing: When and How

Many fire suits include a DWR (Durable Water Repellent) outer treatment that causes liquids to bead and roll off rather than soaking in. This is particularly important for fuel splash resistance — fuel soaking into an unprotected suit increases the calorific load during a fire event.

DWR degrades with washing — typically 10-15 wash cycles before noticeable reduction, though this varies by product. You can test DWR effectiveness by sprinkling water on the suit: if water beads and runs off, DWR is active. If it soaks in and darkens the fabric, reproofing is needed.

Reproofing process:

• Wash the suit clean first (DWR bonds better to clean fiber)
• Apply Nikwax TX.Direct Wash-In during the final rinse cycle per the product instructions — this is the correct product for wash-in DWR on Nomex
• Alternatively, spray-on DWR (Nikwax TX.Direct Spray-On) can be applied to the suit laid flat — better for targeting specific areas
• Activate by tumble drying on low heat for 20 minutes OR ironing through a damp cloth (iron set to low — test on the inside of a leg first)

Important: DWR reproofing does not restore the fire resistance rating of the suit. It restores the fluid repellency layer only. A suit with depleted DWR still has its Nomex fire resistance — it just becomes more vulnerable to fuel absorption before ignition.

When to Retire a Fire Suit

SFI certification imposes a 5-year expiry from the manufacture date printed on the homologation label. FIA certification similarly expires at 5 years. Many drivers push suits well past expiry for practice use, which is legally permissible but not recommended for competition.

Visual inspection triggers for immediate retirement:

• Visible burn damage, charring, or melted areas anywhere on the suit
• Torn or separated seams at the knee, elbow, or waist where loading is highest
• Damaged or inoperable zippers — a stuck zipper in a fire situation is catastrophic
• Faded or deteriorated patches covering underlying fabric condition
• Any confirmed fire exposure, even minor — heat causes invisible fiber damage

For track-only practice use of an expired suit: acceptable risk for many drivers. The fire resistance of the Nomex fiber itself doesn't vanish at exactly 5 years — the certification clock accounts for typical aging and use. A 6-year-old suit that has been properly maintained is probably still more protective than no suit. The question is whether you want the comfort of knowing your suit is within spec at a competition event, which the expiry date addresses.

Budget for suit replacement approximately every 4 years if you race regularly — buying a year before expiry gives time to shop for deals and avoid last-minute tech failures.