Is Cotton FR?

Is Cotton FR? - Flame Resistant

This is the third post in a five-part “FR Clothing Materials” series. Check back to read additional posts in the series, including what is Nomex clothing and what is aramid yarn. And, be sure to read our previous posts, which offer valuable information on topics such as what is FR fabric and what is the difference between fire retardant and flame resistant.

There’s a dangerous misconception that 100% cotton fabric is flame resistant. The truth is, untreated cotton fabric is not flame resistant (FR) – it will ignite and continue to burn against the skin in the event of an arc flash. Watch our video below featuring Tyndale’s Vice President Technical, Scott Margolin, to learn more about the dangers of wearing cotton instead of FR clothing:


In this post we’ll take a look at the safety standard, understand why non-FR fabrics, including 100% cotton, may not be worn as an outer layer – and why you may want to exercise caution even as an inner layer – and share best practices for wearing FR clothing.

OSHA’s previous requirement was simply that a worker’s clothing “do no harm” in the event of an arc flash. As a result, some utilities attempted to meet the requirement by providing employees with a garment made with non-melting natural fibers – rather than FR clothing. It’s true, non-FR natural fiber such as cotton, wool, and silk, are non-melting; however, they’re all still flammable and will ignite and continue to burn if exposed to an arc flash.  It’s important to remember that the majority of catastrophic injuries and fatalities are caused by flammable clothing ignition, not by the arc itself.  Non-FR synthetics and synthetic blends are flammable, meltable, and should never been worn when an arc flash hazard is present.

In April 2014, OSHA published the final rule revising 29 CFR 1910.269 and 1926 Subpart V, related to the construction and repair of electric power generation, transmission and distribution, in an effort to improve workplace safety. This final federal ruling, enforced in August 2015, represents a distinct departure from the past, as it now explicitly requires employers to provide employees with full-body FR clothing matched to the hazard. For a valuable demonstration of why OSHA’s requirement for full-body FR clothing is important, watch this video taken when Tyndale tested a pair of FR jeans against a pair of non-FR 100% cotton jeans.

OSHA’s language in the final ruling makes it clear that only the outer layer of clothing must be FR. However, OSHA also prohibits the use of flammable layers of clothing beneath FR layers of clothing when doing so presents a burn hazard and “could increase the extent of the burn injury.” So, while the standard technically allows 100% cotton to be worn as an inner layer with an FR outer layer, it’s important to keep in mind that it may not provide adequate protection in arcs exceeding the arc rating of the outer garment.

If the FR outer garment is overwhelmed by an arc, breakopen occurs, exposing the flammable inner layer, which can ignite and continue to burn – significantly adding to injury. Therefore, as a best practice, Tyndale does not recommend using 100% cotton, even as an inner layer.


Tyndale provides managed clothing programs to electric utilities across the US, allowing employees to order from a catalog of approved garments that meet all company safety and image requirements. Ready to get started in a Tyndale program? Contact us today! Or, if you have a technical question, feel free to contact Tyndale’s VP Technical, Scott Margolin for a one-on-one consultation.

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