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

09:00
23 December 2022

What does salt do?
The science of gritting

gritter

Contrary to popular belief, salt does not stop snow from settling, so what exactly does it do?

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.

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
50 years since historic 1976 heatwave. Three-month hot spell. . . Tuesday, 23 June 2026
Black-and-white photograph from the 1976 UK heatwave showing a crowded outdoor swimming area packed with people bathing, wading, and sitting along the water's edge during extreme summer heat.
Tuesday, 23 June 2026

Three-month hot spell

50 years since historic 1976 heatwave
June temperature record broken again. Three days running. . . Friday, 26 June 2026
Temperature map of eastern England showing extreme heat around Ipswich and nearby areas, with temperatures reaching 36°C near Cambridge and a large red thermometer icon highlighting intense heat.
Friday, 26 June 2026

Three days running

June temperature record broken again
How to sleep better in warmer weather. Tropical nights ahead. . . Tuesday, 23 June 2026
Person sitting on the floor indoors beside a running electric fan, cooling down in a sunlit room during hot weather, with sunlight streaming through a window.
Tuesday, 23 June 2026

Tropical nights ahead

How to sleep better in warmer weather
All weather news
This might also interest you
Storm Chandra makes impact. Severe gales & heavy rain. . . Tuesday, 27 January 2026
Split image showing strong winds over the UK on a forecast map and widespread rain and snow on a weather radar map.
Tuesday, 27 January 2026

Severe gales & heavy rain

Storm Chandra makes impact
Historic Storm Éowyn arrives. On this day.... . . Saturday, 24 January 2026
Split image showing a person in a yellow jacket struggling against strong winds and heavy rain on a street at night on the left, and an Irish wind forecast map on the right with red and purple shading, gusts up to 75 mph, and a wind warning icon, divided by a curved white line.
Saturday, 24 January 2026

On this day...

Historic Storm Éowyn arrives
Bright and warm conditions take hold. Spring-like outlook. . . Thursday, 23 April 2026
Split UK map showing warm temperatures up to 21 degrees in orange on the left and clear sunny conditions with temperatures from 12 to 18 degrees on the right, with sun icons across the country.
Thursday, 23 April 2026

Spring-like outlook

Bright and warm conditions take hold
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