Why does salt work as an ice melter?

By January 26, 2011 March 1st, 2021 No Comments

If you live where there is snow, you’ve certainly seen or used salt in the winter, but did you ever stop and wonder why salt is so effective at melting ice?


When salt is added to water, it lowers the water’s freezing point. For example, pure water will freeze at 32 degrees Fahrenheit, but a mixture of salt and water freezes at 15 degrees Fahrenheit. Ice on roads or sidewalks will melt when salted because the ice/salt mixture requires a lower temperature to stay frozen.


Of course, plain rock salt will only help if the outside temperature is close to the normal freezing point (or warmer), so what do you do if the temperature is below freezing?

Many ice melt products are now made of a mixture of rock salt and other chemicals because they work more effectively in a variety of ways.

For example, rock salt with Magnesium Chloride can melt ice in temperatures as low as -25 degrees Fahrenheit. Magnesium Chloride products are also known for being safer for application near plants or grass.

Calcium Chloride, another popular ice melt, is known for being fast-acting. The small, white pellets of Calcium Chloride will burrow down into the ice, breaking it up and making it easier to shovel away.

Blended products, like Power Thaw and Thaw Master, are color coated with blue or green color agents to make even application an easier task. Because these products are blends, they do not contain as high quantities of the harsh chemicals that other ice melters may have — making the blends safe for your pets’ paws.

Although Peterson Salt is best known for its water softener products, during the winter months we also deliver salt for your sidewalk or driveway. Whether you’re concerned about cost, melting speed, or protecting your concrete, Peterson Salt offers a wide variety of products to meet your needs.

For more information on products or our home delivery service, call us at 952-929-0422.


Salt also increases the boiling point of water. This is why some cooks add salt to boiling water: it makes the water warmer and will help food cook faster.