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How Does High Vis Work?

kids in high vis in snow

High-visibility clothing is clothing made of fluorescent material with added reflective tape or shapes. Now for the technical bit…

  • The sun’s ultraviolet rays react with the fluorescent colours to make them appear to ‘glow’ increasing daytime visibility. The effect is stronger in poor light conditions such as in fog or towards dusk.
  • At night, light from sources such as car headlights bounces off the reflective areas to make the tape glow, increasing night time visibility.
  • Some reflective materials are retro-reflective which means the light bounces back to its source. If a car shines it’s headlights on retro-reflective material, most of the light is reflected back to the driver.
  • Other reflective materials are made using glass bead technology which scatters the light, some of it getting reflected back to the driver. High visibility products can include either type.
  • The main thing to remember is:
  • “Fluorescent for daytime visibility, reflective for night”
Fluorescent for Day

Did you know… fluorescent colours help you to be seen in the daytime and near dusk.

  • They work really well in dull or rainy weather and when daylight is fading.
  • On a rainy day it’s hard for drivers to see pedestrians and cyclists so it’s a good idea to wear or carry something fluorescent.
  • Fluorescent colours look really bright because of the way they absorb and emit different kinds of light.
  • Many people don’t realise it but… fluorescent colours don’t show up in the dark or ‘glow in the dark’.To be seen by drivers at night you need something reflective.

  • To be seen day, dusk and night you need something that is fluorescent and reflective.
Different Fluorescent Colours


  • Lots of colours can be fluorescent and used for high vis clothing and bags, not just yellow but red, pink, green and orange too. (These colours are listed on the EN1150 quality standard.)
  • In industry, yellow and orange fluorescent clothing is often worn under health and safety laws (for quality standard EN471). You’ve probably seen police officers, postal workers, lorry drivers, builders and refuse collectors wearing these jackets.
  • Lifeboat crews have orange lifejackets; this colour shows up best against blue and grey water. What colour were your armbands when you learnt to swim?
  • Horse-riders often wear pink as it is a colour not found often in nature and so shows up well against autumn leaves. The Safe Lanes scheme in Mayfield, Sussex has even encouraged motorbike riders to wear fluorescent pink so they can be seen!
  • The colour blue is not so effective for fluorescent clothing; because of its wavelength it is not good at emitting light and the human eye is not so good at seeing blue generally. So if you’ve got a blue school uniform it’s a good idea to also wear or carry something fluorescent to make yourself seen.
Reflective for Night

Did you know…

  • Reflective materials work at night by bouncing back the light from a source.
  • To work properly it needs to be dark and there must be a light source such as car headlights.
  • Light can also be reflected by white or pale objects such as a newspaper or white carrier bag; these will reflect light but scatter it in all directions so a driver will see some brightness.
  • However, special reflective materials work much better. They are called ‘retro-reflective’ because they are designed to bounce most of the light back to its source instead of scattering it. The light from a drivers’ headlights will go straight back to the driver who will see the reflective materials REALLY well.
  • Reflective materials can help drivers to see you three seconds sooner at night – which could save your life.
  • Many People Don’t Realise it but…reflective material on your clothing will not reliably help you to be seen in daytime (unless it is also fluorescent)! Although reflective tape can sometimes glint in the sunlight, it doesn’t show up properly to drivers until it after dark.
Different Reflective Materials

There are different kinds of reflective materials…

  • You have probably seen the silver grey reflective bands on the yellow high vis jackets that builders wear. This is called glass bead tape. When light shines on them at night they shine very bright white.
  • Glass bead tape is low cost and easy to add to a garment which is one reason why it is so popular.
  • Other reflective materials are made of special plastic vinyl. Lots of tiny prism shapes are sealed inside. These prisms bounce the light around and then straight back to the source. This is called microprismatic retro-reflective tape.
  • This plastic tape is quite costly to make but is very long-lasting and can look great as it can be made in lots of different colours, shapes and can even have a holographic effect.
  • It is very popular on better quality, stylish high vis items.
Bright Quiz

Do you know how to be bright? Test yourself here when you have read our ‘Did you Know’ section. Answers below.

  • What kind of material helps you to be seen at night?
  • What helps you to be seen in daylight?
  • Which colour of the following is the most difficult for the human eye to see? Yellow, pink, green or blue.
  • Which fluorescent colour is popular with horseriders in the countryside? Why?
  • Which fluorescent colour is good for lifeboat crews? Why?
  • What do you need for reflective material to work at night?
  • When do fluorescent colours show up best?
  • Why is ‘high vis’ clothing fluorescent and reflective?
  • How much sooner can a driver see you at night if you are wearing or carrying something reflective?
  • Name five types of job where fluorescent, reflective clothing is worn.
  • Reflective
  • Fluorescent
  • Blue
  • Pink. It contrast with colours in nature. Yellow is also popular and more traditional.
  • Orange. It shows up well against blue and grey water and white foam.
  • A light source, eg car headlights.
  • In poor daylight, eg rain, mist or when it’s starting to get dark (but not when it’s dark)
  • So it can be seen anytime – day, dusk and night
  • Three seconds – which could save your life
  • Policeman, builder, lorry driver, postal worker, school crossing patrol (lollipop man/lady)