When a light shines on you at night or in low-light conditions, retroreflective tape on your hi-vis workwear glows luminously. The amazing design and construction of retroreflective material make this possible. Find out how the reflective material on hi-vis clothing works.
Retroreflection vs. Other Reflection Types
There are three types of reflection: retroreflection, mirror reflection, and diffuse reflection. Each type of reflection scatters light differently.
The distinct intensity at which hi-vis reflective materials throw light back is due to retroreflection. The prefix “retro-” indicates an action directed backward, and retroreflection is the process of redirecting light back to the source.
When light hits the surface of the reflective tape on hi-vis clothes, the material sends the light back to the source with minimal scattering. As such, when someone shines a flashlight or headlight directly on retroreflective material, a large amount of the light bounces back toward the person, and the material looks luminous.
When most people consider reflection, they think of mirror reflection. However, this reflection type functions quite differently from retroreflection and doesn’t produce the same effect.
When light strikes a mirror reflector, it comes in at an angle, known as the angle of incidence. The light then bounces off the surface at the same angle at which it arrived, or the angle of reflection. The difference is that the light bounces in a different direction.
Finally, diffuse reflection scatters light at different angles rather than in a concentrated ray. When light hits a smooth surface, it can create a glossy look due to this form of reflection. On the other hand, light striking a rough surface can make the surface appear matte because the light meets it at different angles and becomes diffused when reflected.
Reflective materials do not generate their own light; they can only change the path of the light waves. Therefore, by sending the light waves back toward the source, retroreflection creates a brighter image for people near the source of the light as opposed to mirror reflection and diffuse reflection. This is why hi-vis clothing uses retroreflective material.
Glass Bead Reflective Material
How the reflective material on hi-vis clothing works depends on whether it’s made with glass bead or prismatic material. Glass bead material is flexible and lightweight, making it perfect for wearing during a job that requires a lot of physical activity.
Glass bead material features tiny glass spheres embedded either in a heat-activated adhesive, which won’t bond at normal temperatures, or on fabric. Some manufacturers coat one side of the glass beads in aluminum. In such a case, the beads are placed onto the adhesive or fabric surface aluminum-side down.
When light strikes the glass beads, the beads refract, or bend, the light to the surface behind the bead. Once the beam hits the surface, it passes through the front of the bead and back toward the source.
The chemical and physical characteristics of the glass beads determine the amount of light the material reflects. Variations in glass bead shapes can cause a small amount of scattering when reflecting, making glass bead less efficient than prismatic reflection.
It’s important to note that the glass beads are not protected from abrasion, and over time wear away from repeated contact with other surfaces. Additionally, while glass bead works well in many environments, material reflectivity diminishes when wet because the water droplets cause more light scattering.
Even so, glass beads do a fantastic job of retroreflecting light. And with its characteristic light weight, flexibility, and lower cost compared to prismatic, glass bead is a popular material used for hi-vis clothing.
Prismatic Reflective Material
The other type of retroreflective material is called prismatic or micro-prismatic. Prismatic uses thousands of micro-prisms created from acrylic or vinyl. Manufacturers use a transparent plastic film to protect the prisms.
Thanks to the protective layer, prismatic material avoids abrasive damage. Prismatic tape also performs well in wet conditions and retroreflects light more efficiently.
Prismatic material is heavier than glass bead material. Additionally, in cold conditions, this material stiffens and becomes more unwieldy than glass bead.
It’s also important to keep in mind that glass beads return light at a wider angle than prismatic tape, creating a different reflective effect. At a far distance from the reflective material, an observer near the light source will see a brighter reflection from prismatic material than glass bead. However, many people prefer glass beads for reflecting over a shorter distance because the reflection is visible at more angles, and a greater surface area of the tape becomes luminous.
Reflective Tape in Enhanced Visibility vs. Hi-Vis Clothes
Retroreflective material is an important component of enhanced visibility and high-visibility clothing. Garments must meet strict standards to qualify as hi-vis. While enhanced visibility garments make the wearer more visible, they are used in lower-risk areas because they do not adhere to the same requirements.
The American National Standards Institute (ANSI), in conjunction with the International Safety Equipment Association (ISEA), creates the guidelines for hi-vis clothes. ANSI/ISEA 107 categorizes hi-vis apparel into three types (O, R, and P) and four performance classes (Class 1, 2, 3, and E). The types and performance classes correspond to work settings and outline the minimum levels of hi-vis material needed for safety.
ANSI class level 1 garments require a minimum of 155 square inches of retroreflective tape at a minimum width of 1 inch. In contrast, class level 3 meets the highest minimum requirement of retroreflective material. ANSI class level 3 apparel requires a minimum of 310 square inches of retroreflective material, with a minimum width of 2 inches.
Unlike enhanced visibility clothing, all hi-vis clothing requires fluorescent material in addition to reflective material. This is because retroreflection works best in darkened conditions but does not increase visibility in well-lit conditions. In other words, retroreflective tape does not protect the wearer during the day.
Fluorescent materials in yellow-green, orange-red, and red appear to glow in the daylight. The combination of fluorescent and retroreflective materials provides the most protection for the wearer at night and during the day.
At SafetyShirtz, we put safety first without compromising on style. We create hi-vis t-shirts that look great, feel comfortable, and use retroreflective materials. Whether you need hi-vis or enhanced visibility apparel for your job, shop with us today.