Ice Melt vs. Rock Salt - What’s the Difference?

There’s a bewildering array of choices for ice melt, ranging from rock salt to blends with additives designed to jump up performance. What’s the best choice?

#snowmelt #icemelt #icemelting

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The winter is coming and for areas that enjoy snowfall, that means controlling snow and ice deposits outside your door, on sidewalks, and in your driveway. Snowblowers and snow shovels are mainstays in your snow management arsenal, but good snow and ice melt can make a difference in how manageable snow and ice are.

First, a bit of chemistry. Salty water freezes at lower temps than fresh water does. That’s why you won’t see seawater frozen as often as fresh water. So, if you can create a saltwater layer (brine) when applying salt or ice melt to a surface, your control of the ice or snow can be effective.

When it comes to snow and ice control, brine is the key factor and that affects everything else.

Creating a brine layer is easier the closer the temperature is to 0° Celsius/ 32° Fahrenheit. Even a moderate application of ice melt/salt, with a light snow or ice covering, will have an almost immediate effect on brine formation and melting happening right away.

Brine formation is best accomplished BEFORE snowfall by applying the product to areas where you want to control snow or ice buildup. The second best time is when there is only a light layer of snow.

But what if it is extremely cold, ice has formed, or there is snow already in place? If you are using plain old rock salt, you’ll need to remove the snow and apply salt scattered across the surface as evenly as possible.

If the temps are so low that ice still forms, you’ll need to consider using ice melt products with additives that boost performance. Magnesium Chloride is one such additive. This will lower the freezing point of the brine even further. This chemical is very effective as a pre-treatment and is used by many cold-weather municipalities to treat freeways in advance of a snowstorm. It greatly reduces the bond between snow and ice and the road surface and allows for efficient snowplow operation.

Calcium Chloride is the next step up. When this compound mixes with water, it produces heat. This is called an exothermic reaction, and the heat is real! In very low temps, this allows enough brine to form to break the bond between the ice and surface. When you buy an ice melt product with calcium chloride, is one of the ingredients, but not the entire product. It is mixed with sodium chloride.

Granule size also differentiates between regular rock salt and ice melt products. If the granules are too big, then brine formation is very slow. If too small, the compound melts almost immediately and has very little staying power. The size needs to be just right to allow brine formation but to “slow-release” it.

Another important consideration is the amount of product it takes to get the job done. If you need to apply a lot of salt, and there are flower beds or turf adjacent to the slab, driveway or sidewalk, you risk sterilizing the soil or at least greatly diminishing the ability for plants to grow well. Using ice melt products, at their recommended application rate, means less salt (sodium chloride) will be in the soil, with less effect.

Snow and ice melt products also typically have a colorant added to them that is safe for pets, and won’t stain concrete. This helps you to not over-apply the product as it’s easier to see where it has already been applied. It’s hard to see a white product on white snow or ice!

Also, NEVER apply rock salt or snow-melt products to concrete surfaces that are less than one year old. They haven’t properly cured enough to resist spalling, and surface damage will occur when melt product has been applied and very low temps are reached.

JUST DO IT YOURSELF!

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