Flame Retardant Workwear UK: EN ISO 11612 Explained 2026

August 19, 2026
by GHC UK

Flame Retardant Workwear UK: EN ISO 11612 Explained (2026 Guide)

In a welding bay, a substation, or an oil rig, the garment a worker is standing in is the difference between a stray spark and a serious burn. Yet "flame retardant workwear" is one of the most misunderstood categories in PPE — starting with the name itself, because flame retardant and flame resistant are not the same thing, and the difference decides whether your protection survives the wash.

This guide clears up the terminology, decodes the EN ISO 11612 standard, and helps you match FR workwear to the actual hazard on your site.

Quick answer: what FR workwear does — and the two types

Flame-resistant workwear is designed to self-extinguish rather than continue burning, limiting burn injury and giving the wearer time to escape. There are two ways a garment achieves this:

Treated (flame retardant): standard fabric — usually cotton — treated with a chemical finish. Lower cost, but the protection can degrade over time and with repeated washing.
Inherent (flame resistant): the fibre itself is flame resistant (aramid blends and similar). Costs more up front, but the protection is built into the fabric and lasts the life of the garment.

That single distinction drives most FR buying decisions — and it's the one buyers most often miss.

Flame retardant vs flame resistant: why it matters

A treated garment relies on a chemical finish applied to the fabric. Wash it incorrectly — or simply wash it enough times — and that finish breaks down, quietly reducing the protection below its certified level while the garment still looks perfectly fine. This is the hidden risk with treated FR: it fails invisibly.

An inherent garment can't lose its protection through washing because the flame resistance is the fibre, not a coating on top of it. For high-frequency use, industrial laundering, or genuinely high-risk environments, inherent FR is usually the safer long-term investment despite the higher purchase price. For lighter-duty or lower-frequency use, quality treated FR — cared for correctly — does the job at a lower cost.

EN ISO 11612 decoded: the letter codes

EN ISO 11612 is the core European standard for clothing that protects against heat and flame. After the base flame-spread requirement, garments carry letter codes showing which specific heat hazards they've been tested against:

A — Limited flame spread (A1 surface ignition / A2 edge ignition). The baseline every EN ISO 11612 garment must meet.
B — Convective heat (heat carried by hot air/gases)
C — Radiant heat (heat radiated from a source like a furnace)
D — Molten aluminium splash
E — Molten iron splash
F — Contact heat

Each letter carries a performance number (1–3 typically) indicating the level. So a foundry garment might be rated for E (molten iron) where a general welding garment prioritises B and C. Match the codes to the hazards your workers actually face — don't pay for molten-metal protection a data-centre electrician will never need.

The other standards you'll see alongside it

FR workwear rarely carries EN ISO 11612 alone. Depending on the industry, you'll see it combined with:

EN ISO 11611 — specifically for welding and allied processes. If your team welds, look for this, not just 11612.
EN 1149-5 — anti-static/ESD performance. Essential where flammable atmospheres exist (oil & gas, petrochemical), because a static spark is itself an ignition source.
IEC 61482 — electric arc flash protection. Non-negotiable for electrical utilities and substation work.
EN 13034 (Type 6) — limited chemical splash, often combined for oil & gas.

The right combination depends entirely on the role. A rail electrification worker, a MIG welder, and a refinery operative all need FR — but they need different certified combinations of it.

Matching FR workwear to your industry

Welding & fabrication: EN ISO 11611 + 11612, prioritising molten-metal and contact-heat codes. Explore FR workwear and pair with the right heat resistant gloves.
Electrical & utilities: EN ISO 11612 + IEC 61482 arc-flash rating.
Oil, gas & petrochemical: 11612 + EN 1149-5 anti-static + often EN 13034 chemical splash.
Rail: FR combined with high-visibility to the relevant rail specification — see the rail spec clothing range.

The washing trap that quietly voids your protection

This is where treated FR most often fails in the field. Domestic detergents, fabric softeners, and high-temperature washes can strip or mask a treated finish — and once it's gone, it's gone. Always follow the manufacturer's care label to the letter, avoid fabric softener entirely on FR garments, and for teams with heavy usage, consider a specialist industrial FR laundering service that's set up to preserve the finish.

Inherent FR sidesteps this problem, which is a large part of why it wins out for high-frequency environments despite the higher up-front cost.

Don't let the base layer melt onto the skin

Here's a safety point that's easy to miss: a standard synthetic base layer worn under FR workwear can melt onto the skin in a flash fire, causing worse injury than no base layer at all. Polyester and nylon melt; that molten fabric bonds to skin. Anyone wearing FR outerwear in a genuine flame-risk environment should wear a non-melting base layer — FR-rated or natural fibre — underneath. The FR coverall protects nothing if what's under it is melting.

Custom branding on FR — do it right

Company logos on FR workwear are common, but heat-applied badges and non-FR embroidery threads can compromise the garment's certification at the point they're applied. If you want branded FR kit, use a supplier who applies FR-compatible badging that maintains the garment's rating. Our custom workwear service can advise on compliant branding for FR garments so you get your logo without voiding the protection.

Frequently asked questions

What's the difference between flame retardant and flame resistant workwear?
Flame retardant usually means standard fabric treated with a chemical finish, which can degrade with washing. Flame resistant (inherent) means the fibre itself resists flame, so the protection lasts the life of the garment. Inherent is more durable; treated is lower cost.

What does EN ISO 11612 mean?
It's the European standard for clothing protecting against heat and flame. Letter codes (A–F) show which specific hazards the garment is tested against — flame spread, convective heat, radiant heat, molten metal splash and contact heat.

Does washing affect flame retardant clothing?
Yes — for treated FR. Incorrect washing, high temperatures or fabric softener can strip the finish and reduce protection. Always follow the care label. Inherent FR is unaffected by washing.

Can I wear a normal base layer under FR workwear?
No. Synthetic base layers can melt onto the skin in a flash fire. Wear a non-melting or FR-rated base layer under FR outerwear.

Which FR standard do I need for welding?
Look for EN ISO 11611 (welding-specific) alongside EN ISO 11612, prioritising molten-metal and contact-heat performance codes.

Get the right FR spec for your team

FR workwear is one area where buying on price alone is a genuine risk — the wrong certification, or the wrong type for your wash cycle, can leave workers under-protected without anyone realising. Browse the full flame retardant workwear range, or call our team on 0121 555 8446 for help matching the right certified combination to your industry and usage. We'll spec it properly — including compliant custom branding if you need it.

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