Traditional brown rock salt is the nation’s favourite de-icing salt, with its characteristic high-visibility colour and the efficiency with which it dispatches slippery patches for pedestrians and motorists. But why is it such a quality product?
Sodium chloride – otherwise known as NaCl – is a natural, safe de-icing salt, most commonly known as rock salt or road grit, though it does actually have other forms that can also be used to the same effect.
Traditional brown de-icing salt is the cheapest and safest way to made roads, pavements and car parks safer. In the UK, quality brown de-icer salt holds a quality mark, BS 3247:1991. All salt packaged using this British Standard and described on the bag as ‘rock salt’ must meet or exceed certain standards.
British Standard Quality De-icing Salt
BS 3247:1991 de-icing salt must not contain moisture above 4% and its granular size is also controlled: a good guide for the grain size of traditional brown de-icer salt is around 6mm. This means it will easily flow for distribution through gritting equipment and provides traction on road surfaces.
In a high-profile prosecution this year by Trading Standards in West Yorkshire, a company was fined for claiming they were selling rock salt. Tests on their product revealed that it contained only around 20% rock salt, bulked out with sand and gravel. Customers had complained of excessive sand residues and poor de-icing action.
To further put this into perspective, the Highways Agency itself does not use sand to facilitate de-icing, so it would not seem diluting an effective de-icer salt with sand is a particularly good idea. There are mineral-based products on the market which have been developed for the purpose of complementing the use of de-icer salt or replacing it when national stocks are under high demand.
Traditional Brown De-icing Salt
Traditional brown de-icer salt gets its colour from mineral deposits in the seam: while brown is most common, it can also be coloured pink or grey. Its colour, when spread, can give road users and pedestrians peace of mind that gritting has taken place, or that an area has been sufficiently treated.
It is mixed with an anti-caking additive so it can be stored for longer in salt bins, silos and bags, while retaining its quality, as long as it is kept moisture-free and is not subjected to rain run-off, which dilutes its high sodium chloride properties.
Rock Salt: A Summary
De-icing salt:
• Should bear the British Standard BS 3247:1991
• Should never be mixed with sand or gravel
• Should only be mixed with a mineral de-icer if necessary
• Is best used as-it-comes from your reputable supplier
• Is cheap, effective and easy to use
• Should be stored dry and away from moisture
Rock salt can also:
• Be ordered online
• Be delivered in bulk, pallets or IBC
• Be packaged in branded bags at source