If you live in an area that regularly gets snowfall, you know the love-hate relationship with the white stuff. A snowy evening can be a peaceful, beautiful thing—everything gets quiet, and that untouched blanket of snow creates a gorgeous blank slate of a world. There’s sledding, and snow angels, and kids having snowball fights.
And then there’s the cleanup. Snow and ice look pretty for a while, but they also make getting around dangerous and difficult, so the day after a snowstorm is a day of sweaty, back-breaking shoveling. And making sure that no one slips and falls outside your house usually means applying some form of ice melt on your sidewalks, driveways, and steps. While we tend to use the generic term “ice melt” (or the very specific term “rock salt” as a generic), there are actually a lot of different compounds used as ice melt, and each one comes with some pros and cons. In order to choose the right one for your property, here are the basics you need to know.
How does ice melt work?
No matter what an ice melt product is composed of, they all work in essentially the same way: By lowering the freezing point of water so it remains liquid at lower temperatures. That’s why the majority of ice melt products are salts of some kind—salt is very effective at lowering the melting point, preventing surface water from freezing, which in turn allows it to melt the underlying ice. Dumping a layer of ice melt on your sidewalks is an effective way of keeping them clear of ice both before and after a storm. Some ice melts don’t use salts, but rely on compounds that have a similar effect.
When choosing an ice melt, you need to know the main ingredient it’s using to melt your ice, because that in turn will tell you a few basic facts:
- Effective temperature. Different compounds can melt ice down to a specific temperature. If you live in an area where the temperatures routinely drop below 15 degrees or so, some ice melts simply won’t work well.
- Damage and danger. All ice melts can be dangerous to your property in different ways. Your choice of ice melt may depend somewhat on whether you’ve got more hardscaping or more plant life around your property, and whether pets will be exposed to it.
- Liquid or solid. When ice melt combines with water, it becomes what’s known as “brine,” which in turn helps prevent ice from forming. Pre-brined ice melt in liquid form is sometimes a better choice for dealing with ice and snow because it works faster since it doesn’t have to turn into brine in the first place.
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So what are your choices when it comes to choosing an ice melt?
Ice melt compounds
Here are the different compounds commonly used in most ice melts you can buy—note that some manufacturers combine two or more of these to create a specific effectiveness profile:
- Sodium Chloride: This is what the term “rock salt” specifically refers to—it’s just salt that comes in large, rock-like chunks. Sodium chloride is your cheapest option, and it technically works down to about 5 degrees—but in reality, you’ll see a drop off in effectiveness once the temperature drops below 15 degrees. While all chlorides will corrode your hardscaping, rock salt can be the worst of them because of the sharp edges that can really scratch up surfaces. On the flip side, that can also provide better traction.
- Calcium Chloride: This stuff works in temperatures as low as minus 25 degrees, so it is a better choice than rock salt if you live in an extremely cold area. It also works faster than sodium chloride, and it won’t corrode concrete in the same way. On the other hand, it’s more dangerous to handle as it can burn skin (as well as animal paws). This is often added to other ice melt compounds to lower the effective temperature.
- Magnesium Chloride: Effective at temperatures as low as minus 5 degrees, magnesium chloride is less damaging to both hardscaping and landscaping. It’s also generally considered a safer choice for ice melt for kids and pets because it’s less irritating to skin and paws. But there are drawbacks: It’s expensive, doesn’t work as fast as some other choices, and you need to use a lot more of it than other ice melts.
- Calcium Magnesium Acetate: You’ll find this in a lot of liquid ice melts, and it’s often touted as an environmentally safe ice melt because CMA is less damaging to plants, less corrosive than some other choices, and is biodegradable. But be careful—some ice melts use CMA as a coating around regular old rock salt and slap an “environmentally-friendly” label on it, but once the CMA melts off the rock salt, you just have a bunch of sodium chloride everywhere, making the claim meaningless.
- Sodium Acetate: One of the most common alternatives to chloride-based ice melts, sodium acetate works well down to about zero degrees, and it has a long “residual effect,” meaning it keeps melting ice for a long time after you apply it. It’s one of the most expensive ice melts you can buy, however, so if you’ve got a lot of sidewalk to worry about, it might be a budget-busting choice.
- Potassium Acetate: Typically found in liquid form, this ice melt has been gaining traction with some government agencies looking to avoid chloride-based ice melts because it works fast and is effective at low temperatures. However, it’s an expensive option and the environmental impact—especially on aquatic wildlife once it gets into the water system—hasn’t been adequately assessed yet.
- Pet-safe: Let’s be clear: No ice melt is entirely safe for pets. Chloride-based ice melts will irritate their skin and paws, and if they lick the stuff off, it can make them ill. Most “pet-safe” ice melts will use either ethylene glycol or propylene glycol, both of which are actually very effective at melting ice and won’t irritate their paws. But ethylene glycol is essentially antifreeze, and it can be fatal if ingested; and while propylene glycol is safe for dogs it’s actually not safe at all for cats, so be very careful about its use. Even if you use a pet-safe ice melt, you should consider walking your pets through a water rinse after they’ve been outside.
You might also see ice melt based on urea, but it’s not very common these days outside of some industrial applications because it has an extremely dire impact on the environment.
Your choice of ice melt depends on how cold it gets in your area, how much property you have to manage, and the mix of hardscaping, landscaping, and pet access you need to worry about. Knowing what’s in the products you use is crucial to protecting yourself and your pets.