When should you put grit down
Knowing when to put grit or salt down is key to making it worthwhile as it doesn't have an instant effect.
Putting salt down works best as a preventative measure so needs to be done before ice has formed.
Salt works by dissolving into a brine solution which has lower freezing point than that of normal water. This is why sometimes when a surface has been regularly gritted it can appear as though it is wet. This is the salt working exactly how it should.
Salt needs to be put down with enough time to dissolve but the speed of this process is dependent on two main factors
1) Traffic - Vehicle or pedestrian traffic using an area which has been gritted is going to help crush the salt and speed up the dissolving process.
2) Humidity- The higher the humidity or more moisture there is in the air the faster the salt will dissolve.
On some pathways etc with little to no foot traffic when there is little to no moisture you may find salt takes over 24 hours to fully dissolve.
When do we put grit down
Most of our gritting work is done in the early evening or overnight, we will always endeavour to complete our runs at least 6-12 hours before there is a risk of ice. Below are some of the reasons we grit at these times;
- Gritting whilst most businesses are shut means there is less risk to their staff and you can get better coverage when car parks when they are not filled with cars.
- Unless an area is has extremely high amounts of traffic the salt we put down will be effective for at least 24 hours.
- Under normal traffic and moisture levels this will give the majority of the salt enough time to dissolve.
