Flame-resistant (FR) jackets and coveralls get most of the attention when it comes to workplace safety—but what’s underneath matters just as much. Your base layer could be the difference between walking away from an incident or sustaining a serious injury during an arc flash or flash fire. So is 100% cotton good enough, or do you need FR-rated base layers?
Let’s dig into the facts.
Why Base Layers Play a Big Role in Protection
If you work in high-risk industries like oil & gas, power generation, manufacturing, or construction, you know exposure to heat and flame is part of the job. While FR outerwear is designed to shield you, your base layer acts as a second line of defense—and it matters more than most people realize.
In the event of an arc flash or flash fire, wearing the wrong underlayer can cause serious harm. Regular fabrics can catch fire or melt, even underneath compliant FR clothing. That kind of failure can turn survivable incidents into catastrophic ones.
The Cotton Myth: “It Doesn’t Melt, So It’s Safe”
A common belief is that 100% cotton is a safe choice because it doesn’t melt like polyester. But while it doesn’t melt, cotton does ignite—and once it catches fire, it continues to burn. That means even if your outerwear is flame-resistant, cotton underneath can fuel a fire directly on your skin.
Both OSHA and NFPA 70E strongly advise against wearing flammable materials like cotton, polyester, or blends under FR clothing.
What Makes FR Base Layers Different?
FR base layers are made from fabrics that are either inherently flame-resistant or chemically treated to resist ignition. Key benefits include:
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Self-extinguishing performance
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No melting or dripping
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Lower risk of serious burns
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Moisture-wicking and breathable materials for comfort
They’re designed not just for protection, but also for wearability during long shifts in demanding conditions.
Comparing Cotton vs. FR Base Layers
| Feature | 100% Cotton | FR Base Layer |
|---|---|---|
| Flame Resistance | ✘ No | ✔ Yes |
| Melting Hazard | ✘ Low (but ignites) | ✔ None |
| NFPA 70E / OSHA Compliant | ✘ No | ✔ Yes |
| Burn Contribution | ✘ Yes | ✔ No |
| Comfort | Moderate | High (moisture-wicking) |
When FR Base Layers Are a Must
You should be wearing FR base layers if your work involves:
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Arc flash hazards in electrical work
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Oilfield operations, refineries, or fracking sites
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Chemical processing and manufacturing
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Utility and industrial service jobs
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Any site requiring OSHA or NFPA 70E compliance
Recommended FR Base Layers at Dukel Safety
Stay compliant and comfortable with these top picks:
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Drifire FR Lightweight Knit Long John Pant Base Layer
Inherently flame-resistant and breathable with moisture-wicking performance. -
FR/Arc Flash Resistant Long Sleeve Mock Turtleneck (2-Pack)
Rated at 12 cal/cm² and made for layering comfort under CAT 2 PPE. -
Drifire Thermal Long Sleeve T-Shirt – FR & Arc Flash Resistant
Built for cold environments with breathable, fire-resistant fabric. -
FR Long Underwear Bottom – 15 cal/cm²
Lightweight and protective, ideal for Category 2 to 3 job sites. -
Hi-Vis FR T-Shirt, CAT 1, Short Sleeve
Inherently flame-resistant and moisture-wicking, ideal for warm weather tasks.
Compliance That Starts at the Base
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OSHA 1910.269: Specifies that clothing worn during electrical work must not ignite or melt.
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NFPA 70E: Requires a full system of protection, including base layers, that minimizes thermal injury during arc flash events.
Bottom Line: Cotton Isn’t Enough
Even though cotton won’t melt, it’s still flammable—and that makes it a liability under FR clothing. Flame-resistant base layers are engineered to work as part of a complete protection system, helping reduce burn injury and support compliance.
At Dukel Safety, we carry a wide range of FR base layers built for protection, performance, and all-day comfort. Because real safety starts with what you wear closest to your skin.
