High-visibility (also hi-vis or hi-viz) clothing uses two specific material properties
- Fluorescence
Usually used as the major material in the fabrication of the garment.
This uses the property of a material where it absorbs light at one wavelength, but then reflects back light from the visual spectrum.
See Fluorescence
- Reflectivity or more increasingly Retroreflectivity
Usually added to the clothing as bands of tape. The tape is added to give visual clues that garment is being worn buy a person by placing them on the body, arms and legs. The quantity and placement of these bands can affect how quickly the brain realises that this is a person, especially if they are not moving.
See Reflectivity
Generally, fluorescent materials work to increase daytime visibility (including dusk & dawn), whilst reflective materials are primarily used to increase night time visibility.