Our How It’s Made series gives you a “behind the ‘seams’” look at everything that goes into making the life-saving clothing you wear every day: from fiber, to yarn, to fabric, to finished garment, and the science that imparts flame resistance along the way – all with videos and commentary from industry experts.
So far in FRC: How it’s Made, we’ve seen how fibers are generated, then spun into yarn and woven into fabric. But what is the process to impart arc and flame resistance?
Scott Margolin, Vice President of Technical, delves into the process – explaining the difference between inherent and treated fabrics, and how the arc and flame resistance is engineered:
There are a number of processes for creating quality, durable protective fabrics, but they can essentially be grouped into two basic categories: inherent and treated. Both processes, when done properly, can create flame resistance that’s guaranteed for the life of the garment.
The truth is that ALL arc-rated and flame resistant clothing (known as “AR / FR clothing” or simply “FRC”) in common use for secondary PPE in the USA today are made from fabrics engineered through chemistry. The main difference between inherent and treated fabrics is that the engineering of inherent AR / FR fabrics is done on the fiber level, while the engineering of treated AR / FR fabrics is done at the fabric level (but usually still inside the fibers).
Inherent AR / FR Fabrics
If you’re familiar with the Fire Triangle, you know that there are three ways to extinguish a flame – remove the heat, the oxygen, or the fuel. Some inherent fibers char instead of burning, which removes the fuel, and some both char and actively extinguish using free radical oxygen scavengers, which, as the name implies, remove the oxygen. The continuous fiber is then chopped into short lengths, crimped, then it’s ready to be spun into yarn and woven into fabric.
Treated AR / FR Fabrics
Treated AR / FR, on the other hand, refers to a fabric that has been engineered with flame-resistant chemistry to include AR / FR properties that were not present prior to the treatment. Treated products begin with a fabric and conduct the AR / FR engineering within the existing fibers of that fabric.
Most treated fabrics are cotton-rich, and manufacturers are able to create an AR / FR fiber inside the hollow core of the cotton fibers, where it won’t be washed or worn out. The various processes differ somewhat, but most involve THPC chemistry, which is applied as a liquid by running the fabric through a bath and enabling the solution to penetrate the core of the hollow fibers. Once the fabric is properly wet out, it runs through rollers that set the correct temperature and other important parameters, and is then transferred into a gaseous ammonia cure chamber. This chamber is where polymerization occurs. Polymerization of the garment cures the new AR / FR fiber matrix inside the hollow cotton core. It’s like a two-part epoxy you’d get at your local hardware store: there’s a part A and a part B; once you mix them, they form a new substance (part C) and there is no going back to part A or B.
The fabric that emerges from the chamber is now flame resistant and ready to be scoured, rinsed, and finished. Like many of the inherent fabrics, these AR / FR cotton fabrics char instead of burning…no fuel, no fire. Just like inherent fabrics, many treated flame resistant fabrics are AR / FR for the life of the garment.
As you can see, both inherent and treated AR / FR fabrics use complex chemical engineering processes to create their life-saving properties, and both result in durable, reliable fabrics.
In fact, all FRC Tyndale sells is guaranteed arc- and flame resistant for the life of the garment and is easily washed at home without special handling.
Want to learn more about how arc-rated and flame resistant fabrics are tested? Don’t miss our How it’s Tested series.
Now that we’ve seen how AR / FR fibers are generated, then spun yarn and woven into fabric, and how arc- and flame resistance is imparted along the way, watch episode 3 to learn how finished FRC is designed, patterned, and manufactured.