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
Record ocean heat halting hurricanes. Strong El Niño influence. . . Friday, 11 September 2026
A weather map shows a calm Atlantic Ocean with no hurricanes, alongside a picture of the sea.
Friday, 11 September 2026

Strong El Niño influence

Record ocean heat halting hurricanes
A marked change in the weather. Cold front heading south. . . Monday, 7 September 2026
Map of Europe showing a cold front stretching from Scandinavia to Spain. Thunderstorms are shown in southern and central Europe.
Monday, 7 September 2026

Cold front heading south

A marked change in the weather
Severe weather hits Mallorca and Italy. Severe thunderstorms. . . Thursday, 10 September 2026
Numerous thunderstorms are sweeping across La Palma. The many lightning symbols on the radar and lightning map show that there is heavy lightning activity across large parts of the island. The thunderstorms are striking particularly in the island’s interior and in the south. On the right, you can see the aftermath: a large fallen tree has buried a car beneath it. Emergency services are clearing up the damage. So, along with the thunderstorms, not only heavy rain but also gusts of wind can become a problem.
Thursday, 10 September 2026

Severe thunderstorms

Severe weather hits Mallorca and Italy
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
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