Ice Melt vs Rock Salt: The Differences Explained + Which is Best For Melting Ice

Ice Melt vs Rock Salt

Ice melt and rock salt are both used for removing ice and not necessarily for removing snow.  You need to remove the snow layer with a shovel, blower, or snow thrower before applying ice melt, which ever product you choose to use.

Ice melt and rock salt are both very good at causing the ice to melt even in for low temperatures but they do work differently and have their own advantages.

Rock salt works by lowering the freezing temperature of water causing some ice to melt because of the introduction of sodium chloride into the environment whereas ice melts based on magnesium chloride or calcium chloride’s cause chemical reactions that result in heat which then begins melting the ice.

There are however other kinds of ice melt that use different compounds and in most premium products there are mixtures of these compounds that are used to maximize their benefits while also minimizing their drawbacks.

To start please take a look at this quick comparison video I produced to serve as an overview of this topic.

With that out of the way let’s now look into the details associated with the majority of all the ice melt products and learn a bit about what makes certain products better to use in various situations.

Quick Review of the Different Types of Rock Salt and Ice Melts

Ice melts are made from a series of different chemical compounds and some are even mixed with rock salt to lower the cost and change the use of the product.

  • Rock Salt
    • Works very well down to around 15 degrees Fahrenheit. Does work below this, however it will take longer to be effective.
    • Coarser and will provide traction making it easier to walk or drive on prior completely deicing an area but will remove a finish on tile and is not recommended for use on new concrete.
    • Rock salt will not heat up the water, it only melts the ice due to creating a brine with the water and salt. Sometimes this leads to refreezing prior to being able to runoff the water.
  • Calcium Chloride
    • Calcium Chloride is the best product for extremely low temperatures as it is effective down to negative 25 degrees.
    • It is the quickest at melting ice.
    • It is also relatively safe to use around animals, vegetations, and lawns.
    • Calcium chloride works by reacting with water releasing a chemical heat that can be heat up very quickly and to a high temperature.
    • If choosing between calcium chloride and magnesium chloride know that you can apply less calcium chloride and get the same results making a bag last longer.
    • It is more expensive and some users have reported that it can still damage grass and plants, so be careful about where you apply just because it states that it is safe with vegetation doesn’t mean that it can heavily applied near sensitive plants.
    • If your runoff is close to a stream or creek on your property this product is safer for aquatic life than magnesium chloride.
  • Magnesium Chloride
    • Magnesium Chloride works down to negative 15 degrees Fahrenheit, but its most effective range is down to around negative 5 degrees.
    • It is very safe to use on concrete, while it is wise to avoid spreading it over granite, tile or other walkway materials that have a finish.
    • This is the best option when you need to be concerned about pets or children ingesting the material and when it may get near plants and grass.
    • When reacting with water it can heat up between 75 and 90 degrees due to the chemical reaction resulting in a quick melt.
    • The only downside to this product is it comes in a shale flake form, it is not pelleted so it can jam a spreader making it more difficult to apply.
  • Combination product magnesium chloride and salt
    • Magnesium Chloride with Salt is a salt product encapsulated with magnesium chloride.
    • Excellent for use in temperatures that don’t get below 10 degrees.
    • It gets a quick heat, but not as high as pure magnesium chloride.
    • It is a less expensive product than magnesium chloride and calcium chloride.
    • The product Purple Heat marks the areas that you have applied by turning the snow and ice purple allowing you to visually see where the product has been laid.
  • Combination product magnesium chloride and sodium chloride
    • Magnesium Chloride Blended with Sodium Chloride is similar to the magnesium chloride and salt, however the difference is instead of being encapsulated with the magnesium chloride, this product is completely blended through.
    • This will allow the product to be used down to lower temperatures than the encapsulated combination.

In almost all cases each of these products works best when they applied directly to an ice layer instead of a layer of snow sitting on top of ice. I like to use my leaf blower to remove loose thin layers of snow but for thicker layers a good shoveling works if you don’t have a plow or a snow blower.

See the following pages for my recommendations for residential use battery blowers and snow blowers.

What is Rock Salt?

Rock salt is also known as Halite, which is the mineral form of sodium chloride. Rock salt works by lowering the freezing point of water when it comes into contact by being spread onto ice. When the salt encounters the partially melting ice it forms a brine which is simply a combination of water and salt. This brine solution can then flow under the ice and assist in breaking the bond between the ice and pavement. Rock salt works down to 5°F and helps provide instant traction on snow on ice, especially when combined with sand it can be an excellent solution for making your driveway safe to walk and drive on.

Pros of Rock Salt

  • Rock salt is the cheapest ice melting product available
  • It is readily available in all retail and online stores except during shortages due to extreme weather in the forecast and people stocking up
  • It has a low freezing point of 25 degrees Fahrenheit

Cons of Rock Salt

  • Can be harmful to plants and lawns
  • It can be harmful to your family pets if they ingest it.

What is Ice Melt

Ice melt, generally, is a blend of the following chemicals: sodium chloride, magnesium chloride pellets, and calcium chloride pellets. Calcium chloride is well known as the best performing ice melt for quickly melting ice and lasting the longest at the lowest temperatures. It is capable of  melting ice down in outside temperatures as low as negative 15°F and some products even advertise lower temperatures. Ice melt often comes in the form of flakes, but can also be a combination product with salts and be in a pelletized version for easier spreading via a drop spreader or broadcast spreader.

Pros of Ice Melt

  • Most ice melt products contain calcium carbonate which can lower the freezing point of water
  • Forms both a brine like rock salt, but also generates a chemical heat making it effective faster
  • There are several different variations of the product with slightly different blends for different needs.

Cons of Ice Melt

  • Generally, more expensive
  • Quicker to run out of at the store during extreme weather so plan ahead
  • Comes in pet friendly versions

Alternative’s to rock salt or Ice Melt’s to consider

  • Sand, this will give you a little traction and make it easier to walk on versus just ice.
  • If you don’t have rock salt, but you have table salt, this can be used in a pinch and will still create a brine.
  • Epsom salt is also an alternative option if you have a bag, while more expensive than table salt it will work.
  • Sugar can also create a brine like solution and assist in melting the ice by lowering the freezing point of the water.
  • Rubbing alcohol can be used and while not as effective as salt it has a freezing temperature down to negative 20 degrees and will work.

Considering all the cons of ice melt you should consider how to minimize the damage it can do to your concrete sidewalks, asphalt driveways, and any decking you may decide to put it on. Make sure to see one of the following articles to learn more about these important topics:

Is Ice Melt Bad For Concrete, Sidewalks, and Driveways?
Can You Use Ice Melt on Wood, Composite Decking, or Roofs?

Ice Melt with Pet Friendly Ingredients

If you have pets or small children, you should be concerned for their safety when selecting home and garden products including rock salt and ice melt.

You can choose a 100% organic, all natural, salt free ice melt that will not harm your pets if they ingest a small amount of the material before it has a chance to wash away. Look at the packaging and read the descriptions and seek out a product that is non-toxic, safe for pets and skin, safe for the environment, and less harmful to plants and grass.

While being safe, the pet friendly ice melts are also some of the more effective and fast acting solutions to deicing.  They will cost a little more than regular rock salt, but they are offer excellent value for the average consumer that wants to be environmentally conscious and use products that are safe for their children and pets to play near.

How to Spread Rock Salt and Ice Melt

Here are some tips for using deicing and rock salt products:

  1. Always clear off the snow first, these products work most effectively being placed directly on ice and will not work well when place onto the top of a fresh layer of snow.
  2. Use shovel or snow blower to clear any snow accumulation off the surfaces you intend to treat
  3. Apply the material in a thin even layer using a salt spreader, but you can also consider using your typical drop spreader or broadcast spreader with the correct setting depending on the size of the material.
  4. If you do not have a spreader, use a cup to sprinkle it or wear gloves and apply it by hand. If you apply too much, thin it out with a broom.
  5. Follow the manufacturer’s instructions for use on the package.

Ice Melt vs Rock Salt: The Right Choice

Depending on the temperature and where you are going to be placing the material pick the right deicer for your situation.  If you have children or pets and will be putting the flakes or pellets around your house, make sure and choose one of the options that is considered pet friendly. 

Be careful with using too much rock salt on new concrete if that is the product you are choosing to buy for this season.  No matter what product you use remember to shovel the snow first before putting down a deicer otherwise it will not work at all.

One last parting thought: Did you ever get around to winterizing your sprinklers? See this post if you are unsure if you need to winterize them.