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
Warm waters raise severe weather risk. Mediterranean bathtub. . . Friday, 4 September 2026
Left: Map showing water temperatures in the Mediterranean; Right: Dark clouds over a stretch of Mediterranean coastline. A bolt of lightning strikes and a curtain of rain can be seen.
Friday, 4 September 2026

Mediterranean bathtub

Warm waters raise severe weather risk
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
Autumn arrives with vivid colour. Your weather - Your shots. . . Sunday, 6 September 2026
Split image showing peach-lit textured clouds above silhouetted trees and golden cumulus clouds reflected in a calm canal lined with boats.
Sunday, 6 September 2026

Your weather - Your shots

Autumn arrives with vivid colour
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
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
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
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