Home
Weather London
WeatherRadar
RainfallRadar
TemperatureRadar
WindRadar
LightningRadar
Weather News
Editor's Pick
Discover the app
Weather widget
Contact us
Apps
Career
    Home / Editor's Pick /

    What does salt do? The science of gritting

06:00
20 January 2023

What does salt do?
The science of gritting

gritter

With frost frequenting our roads amidst the cold weather, we thought it was time to take a look at what exactly gritting the roads does.

Although we often refer to it as gritting, there is usually little grit involved, and instead mined rock salt is used. Salting the roads is primarily a preventative technique, and works most effectively via three main methods:

  • Salt lowers the freezing point of water. Water freezes at 0C but the presence of the salt prevents water from freezing until -6C to -8C.
  • It stops snow bonding as ice to the road, so can be ploughed away more easily.
  • Can also be added post-snow to small depths of lying snow (up to around 4cm) to help dissolve and melt it away.

Salt is most commonly used because it is what we call hygroscopic. It acts like a magnet by drawing in and absorbing moisture from the air and the road surface, to the granules.

If the air is too dry, or it hasn't rained recently, salt can be pre-wetted. It also needs a flow of traffic to be worked into the road properly. And if there is no moisture present, the salt won't be absorbed and thus won't do its job.

Salt can also be ineffective at particularly low temperatures, so if you live somewhere like the Scottish Highlands, then it's likely that a mix of salt and grit will be used.

Other alternatives aside from salt include molasses, although depending on where you live, can often get licked up by sheep, which is a road hazard in itself!

Each year new names are unveiled for council's gritter lorries, with this year featuring David Plowie, Salt Disney, Sled Zeppelin and Sleetwood Mac.

Weather & Radar editorial team
More on the topic
Clouds return to capture the scene. Your weather - Your shots. . . Sunday, 26 July 2026
Waxing crescent Moon above vivid pink and magenta sunset clouds, with silhouetted trees along the horizon beneath a deepening blue twilight sky.
Sunday, 26 July 2026

Your weather - Your shots

Clouds return to capture the scene
Half of England now in drought. Joining North Wales. . . Wednesday, 29 July 2026
Dry section of the River Thames beneath a small stone bridge, with the riverbed exposed and cracked after prolonged, dry weather, while a person walks along the roadside above.
Wednesday, 29 July 2026

Joining North Wales

Half of England now in drought
Floods and landslides in parts of Asia. An unusual monsoon. . . Wednesday, 29 July 2026
Split image: On the left, flooded villages and fields can be seen in a vast landscape. On the right, a weather map of India shows heavy rainfall, along with a warning sign featuring a car in floodwater.
Wednesday, 29 July 2026

An unusual monsoon

Floods and landslides in parts of Asia
All weather news
This might also interest you
Turbulent weather in the Canary Islands. Storm and rain. . . Friday, 12 December 2025
Weather graphic showing rain and wind fields over the Canary Islands and a central warning symbol.
Friday, 12 December 2025

Storm and rain

Turbulent weather in the Canary Islands
Super Typhoon Bavi threatens Taiwan. Up to 1,000 mm of rain. . . Wednesday, 8 July 2026
The image shows an intense tropical cyclone over the western Pacific, east of Taiwan and the Philippines. The centre of the system is depicted as a light purple and white vortex with a clearly visible eye, surrounded by a ring of red and orange areas indicating the strongest wind speeds. A white arrow marks the typhoon’s predicted track towards the north-west, in the direction of Taiwan. To the west of the storm lie the Philippines, with the cities of Manila and Cebu; to the north of these lies Taiwan, with Taipei. Further west, the Chinese coast, including Hong Kong, and parts of Vietnam can be seen. The coloured wind map shows predominantly green areas outside the storm’s core, indicating significantly weaker winds. White streamlines illustrate the typhoon’s anti-clockwise circulation in the Northern Hemisphere. The highest wind speeds are concentrated around the eye of the cyclone.
Wednesday, 8 July 2026

Up to 1,000 mm of rain

Super Typhoon Bavi threatens Taiwan
Long-term trends need a pinch of salt. 40 °C in July?. . . Tuesday, 30 June 2026
Temperature radar of 2022 heatwave where the all-time temperature record in the UK was set. Warning symbol overlain.
Tuesday, 30 June 2026

40 °C in July?

Long-term trends need a pinch of salt
All articles
Weather & Radar

Weather & Radar is also available on

Google Play StoreApp Store

Company

Contact us Privacy Policy Legal info Accessibility statement

Services

Uploader

Socials

facebooktwittertikToklinkList