How Does High Vis Work?

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.
By wearing or carrying something ‘high vis’ which has both fluorescent and reflective materials, it will help you to be seen day, dusk and night: ‘Fluorescent for day, reflective for night’.

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.

However…

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 EN20471). 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 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.

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. So, for example, putting a reflector on a young child’s school bag will not help them to be seen as most journeys to and from primary school are in daylight or near dusk… unless it is also fluorescent which shows up in daytime/dusk.

There are different kinds of retro-reflective materials…

Micro-prismatic Tape

Micro-prismatic tape is 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 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.

Glass Bead Reflective Tape

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. You can see it on our traditional high vis waistcoats.

Do you know how to be bright? Test yourself here when you have read our section above. Answers below (no peeking!).

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.

Answers

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)