The Science Behind High-Visibility Protective Fabrics

Workers in high-risk work environments need to feel confident their flame-resistant clothing will also help them be seen by others.

• By Steve Lucas
• Mar 14, 2025

When Hurricane Helene hit the Carolinas last, nearly 20,000 line workers descended upon the Western North Carolina and Upstate South Carolina regions to support the recovery and power restoration efforts. In an all-hands-on-deck situation, these crews worked around-the-clock to restore power to the millions of customers across the Carolinas who were forced to live off-the-grid, some going weeks without power. 

This work wasn’t typical 9-to-5 work either. With shifts that could last up to 16, 18 or even 24 hours a day, the environments these workers had to navigate were treacherous. Wading through mud, navigating fallen trees and desolate roadways and working in the pitch black put an additional emphasis on the need for high-performance protective apparel. In this situation, these line workers needed to trust the flame-resistant clothing they wore could handle whatever the terrain threw at them. 

Incidents like this force workers in high-risk professions, such as utilities and oil and gas, to think about how the apparel they wear on-the-job is designed and manufactured — and trust they’re working with suppliers who are bringing the most innovative, cutting-edge science to the table. 

Take high-visibility apparel for example, a quick Google search for “hi-vis clothes for line workers” returns dozens of search results — but few go in-depth on what it takes to make FR clothes truly hi-vis. After all, anyone can dye a cotton t-shirt yellow and say it’s ready to help protect you at night, in bad weather or under any other low-visibility situation. The truth is that it takes a reliable manufacturing process, proven FR technology, a perfect dyeing process, and a team with decades of experience developing protective fabrics for these exact situations. 

Understanding the Nuance of Hi-Vis Materials  

To the naked eye, it’s impossible to look at a yellow shirt or vest and be able to tell if it’s high-visibility or not — not just any bright yellow or bright orange shirt can be considered high-visibility. It comes down to the brightness, or the fluorescence in the garment, not the color. 

The easiest way to think about it is like this: take a white T-shirt. Then, put it under a black light and watch as it illuminates. It gives you a bright white that almost looks like it’s glowing or that it has been hit with a highlighter. You’re looking at the same white t-shirt, but your eye looks at it in a different way under a different light. So, you see it shining back as a fluorescent light in the darkness. Again, it’s the same color but your eye is picking up the luminance. 

That’s how you can think about hi-vis garments. When light hits it in the dark, will it shine that bright light, will it illuminate? 

Sourcing and Standards  

If you’re purchasing hi-vis garments for your workforce you want to look for fabrics that have been certified to the ANSI 107 standard. This standard provides guidelines for the design, performance, and use of high-visibility safety apparel (HVSA) across a variety of working environments. Any credible manufacturer will have these certifications readily available for their materials.  

There are various requirements for ANSI 107 but the more challenging requirements to meet for a product that contains cotton is the colorfastness tests. The fabric is submitted to a Xenon light that simulates the potential fading caused by the sun. You must get the color to stay inside a specific region of color space and maintain its brightness, essentially without any fading. 

When sourcing these types of materials, pay close attention to the history and experience of the manufacturer. An influx of copycat fabrics into the market makes it critical that you look at the supplier’s track record with testing, certification and meeting standards. Any reliable manufacturer will be able to provide proof of testing and can answer any questions about the supply chain of the materials.  

How Flame Resistance Impacts Development  

Color space is an important concept to understand when it comes to high-visibility materials. When you think about a color space, think about an American football. Every color you see falls within a three-dimensional space, or this football. What the ANSI says is that your yellow, in this case, must fall within a very specific football and if it doesn't it’s not ANSI 107. But the trick is that it’s not just the color with this standard, it’s the brightness. Manufacturers can get a flame-resistant fabric into the right yellow football; the hard part is making sure it’s bright enough. Which is a totally different football. 

The challenge in the past with cottons has been the propensity to fade with this xenon light test that ANSI runs. Basically, if you’re wearing this shirt out in the sun every day for a month, will the brightness lose its luster? 

Wash durability is another important test and one that can cause some hiccups in the development stage. This test sees that the fabric is washed multiple times and reevaluated for color space and luminescence. The standard only requires you to maintain that brightness after five washes, but there are available fabrics that have been shown to last at least 100 washes and still maintain their color and brightness.  

A Final Safety Note  

While science plays a major role in getting high-visibility garments into the field, the most important thing is that workers want to wear them. Adding multiple layers of PPE can decrease workers range of motion and comfort level, affecting their mindset against the role it plays in keeping them safe on the job.  

To that end, ask suppliers about the textile technology available to limit the layers of fabric needed to address visibility issues and prioritize fabric that also keeps in mind the feel, movement and weight of the garment. For example, multi-hazard fabrics combine FR and hi-vis needs to meet or exceed the industry standards for each hazard.  

This article originally appeared in the February/March 2025 issue of Occupational Health & Safety.