The Challenges of Bringing Stretch to FR Denim

Product developers must consider the variation of stretch, standards, partnerships and laundering.

• By Chris Romansky
• Mar 01, 2023

For many Americans, wearing jeans to work is the ultimate business casual. For workers in the oil & gas and electrical utilities industries, however, simply convincing supervisors that jeans are more comfortable than traditional workwear doesn’t cut it. Just like any PPE, flame-resistant (FR) denim must uphold industry standards and ensure that above all else, workers are protected from the everyday hazards on the job.  

With those considerations in place, denim in these industries wasn’t always the go-to choice. FR denim was first introduced to the industry more than 25 years ago, but like most innovations, those first renditions of FR denim left a few characteristics to be desired.  

For years, FR denim options were stiff, heavy and difficult to move in, especially in hot climates. But in the early 2010s, as workers demanded more fashion-forward apparel choices in their workwear, the industry was forced to address the comfort and style challenges of applying FR technology to denim apparel. Although color was the major initial request—wanting options that more closely imitated vintage washes or were available in lighter hues—stretch quickly became a priority for FR workwear.  

Applying more stretch to FR-engineered denim is a bigger challenge than many workers and safety managers may understand. To grasp the innovation and technological know-how needed to excel at FR denim, it’s important to acknowledge four key considerations during product development.  

The Difference Between Mechanical Stretch and Power Stretch  

When considering how to add stretch to denim, product developers choose between two variations: mechanical stretch and power stretch. Mechanical stretch happens when the manufacturer takes a fabric without any stretch component and through the weaving process, gives the yarns some natural elasticity and in turn, the finished garment is more flexible. Typically with this process, manufacturers expect to see around a six to eight percent stretch percentage.  

Additionally, power stretch denim includes some type of stretch component, like Lycra or Spandex, that gives the fabric the power of stretch. These stretch percentages can get manufacturers closer to the 12 to 14 percent range, which is more noticeable to end users. In some cases, more than 15 percent stretch can be achieved based on technological advancements in the space.  

Standards are a Necessary Challenge  

In the non-FR space, manufacturers are free to set performance measures for wash shrinkage because it is not regulated. Stringent FR performance standards make controlling wash shrinkage important to make sure the safety of the worker over the life of the garment is guaranteed.  

There are two ways to control fill shrinkage in FR. The first is to finish a fabric as narrow as possible so there’s no more room for it to shrink. Alternatively, you can thermally set a fabric at high heat and essentially “lock in” the heat memory to avoid shrinkage. The challenge with adding stretch to FR denim specifically is that it’s incredibly difficult to develop a fabric at a suitable width for cutting and sewing when there is little to no fiber content that you can thermally set to control wash shrinkage in a powered stretch fabric.  

Strategic Partnerships are Critical  

Because it’s so difficult to develop fabric that can be engineered during the finishing process and uphold both stretch and FR properties, finding the right material supplier is key. Companies that have proprietary technologies to address stretch play an important role in FR fabric manufacturers' ability to bring more options to the marketplace.  

Durability and Longevity through Laundry Processing  

Industrial launderers can be in high-caustic, high-detergent environments, which historically could have been detrimental to FR stretch apparel. However, stretch polymers have come a long way in terms of chemical stability. Now, technological advancements in both stretch polymers and the way FR fabrics are processed have made it possible to maintain stretch performance without sacrificing durability.  

While the industry likely won’t see every retail trend translate over to workwear, denim options at 15 to 20 percent stretch percentage will continue to be in demand. Manufacturers who can navigate the requirements of the standard while pushing the envelope on how stretch and style continue to collaborate will be in the best position to service the market.  

This article originally appeared in the March 1, 2023 issue of Occupational Health & Safety.