Rock salt is a common ice melting tool and is used across the world. It can be spread at night time before the temperature drops to stop the ground freezing over. It leaves a brown residue that can turn sludgy which puts some people off using rock salt, but this quality is also appreciated by others as you can see where you have spread it, especially on snow. Rock salt does not only have ice melting qualities, it also creates traction making it perfect for use on roads and slippery surfaces.