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
Split image showing a warm temperature map across the UK and western Europe on the left and a bright sun shining through scattered clouds in a blue sky on the right.
Friday, 15 May 2026

Much warmer bank holiday

Heatwave? We're not quite there yet
Temperature map of the UK and western Europe showing intense red and orange heat across southern Britain, with temperatures reaching 31°C near London and a large thermometer icon beside the map.
Friday, 22 May 2026

Highs over 30 degrees

Unusually warm for the long weekend
Weather map of the USA showing an active thunderstorm front between Kansas City and Minneapolis. Numerous lightning symbols indicate severe thunderstorms, along with a severe weather warning symbol.
Monday, 18 May 2026

Tornadoes possible

Dangerous thunderstorm front over the US
All weather news
This might also interest you
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
UK temperature map dated 14.02 showing widespread subzero values in blue shading, with readings such as −4 in Glasgow, −3 in Dublin, and −2 in London, alongside a blue thermometer icon.
Friday, 13 February 2026

Icy conditions

A frozen start to the weekend
plit image showing a double rainbow over a rocky shoreline on the left and sheep grazing in a green field under stormy clouds on the right.
Sunday, 2 November 2025

Your weather - Your shots

Mixed conditions on an unsettled week
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