Home
Weather Dublin
WeatherRadar
RainfallRadar
TemperatureRadar
WindRadar
LightningRadar
Weather News
Editor's Pick
Discover the app
Weather widget
Contact us
Apps
    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
Severe thunderstorms in northern Italy. Hail and storm damage. . . Wednesday 3 June 2026
A split-screen image showing fallen trees on a road and a weather radar map of northern Italy. Numerous thunderstorm cells are active between Turin, Milan and Bologna.
Wednesday 3 June 2026

Hail and storm damage

Severe thunderstorms in northern Italy
Spring records for England & Wales. Above-average warmth. . . Tuesday 2 June 2026
Split graphic showing a European temperatures anomaly map on the left with widespread warmer-than-average conditions, and a UK and Ireland heat map on the right displaying intense heat with temperatures exceeding 30 °C.
Tuesday 2 June 2026

Above-average warmth

Spring records for England & Wales
Warmer in Lapland than it is here. Arctic Circle sees 25 °C. . . Thursday 4 June 2026
On the left is the Temperature Radar for Europe; on the right is a picture of a lake in Finland surrounded by woodland.
Thursday 4 June 2026

Arctic Circle sees 25 °C

Warmer in Lapland than it is here
All weather news
This might also interest you
Seasonal warmth between spring thunder. Your weather - Your shots. . . Sunday 19 April 2026
Split image showing coastal sunset with layered lenticular clouds over rooftops and palm trees on the left, and a green valley with river and hills under soft daylight on the right.
Sunday 19 April 2026

Your weather - Your shots

Seasonal warmth between spring thunder
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
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

facebooktwitteryouTubelinkList