With the snow and cold comes the responsibility of removing ice from walkways and driveways. There are multiple options for deicing, and it can be difficult to decide which one is best. Here is a breakdown of the advantages and disadvantages of several common deicers.
By far the most common deicer, as well as one of the least expensive, salt is used on many public walkways and streets. Salt can take many different forms, but one of the more common forms is quite similar to the salt people use on food: sodium chloride. In temperatures above 20 degrees Fahrenheit, salt is a quick and effective deicer. However, sodium chloride is very corrosive and can damage metal, plant life, other organic material, and surfaces such as concrete. As a result, an overuse of salt during the winter can have lasting consequences, including damage to cars and other equipment, damage to clothing and shoes, death of plants near surfaces where salt was used, dry or damaged skin (if exposed), and dry or irritated pets’ paws. Because of this, pet owners in particular tend to search for other options. An overuse of salt during the winter can also increase salt levels in groundwater. Despite these drawbacks, salt remains an effective and readily available option for quickly deicing walkways or driveways, mainly because of its high effectiveness and low price.
One of the most popular products used to melt ice (besides salt), urea has distinct advantages. Urea is a fertilizer made from carbon dioxide and ammonia (not urine!) containing 46% nitrogen, and it melts ice quite effectively. When compared to salt, urea can be a better choice due to its less corrosive properties, meaning that metals, concrete, fabrics, and skin are not as irritated or damaged as they are by salt. This makes urea an excellent choice for people with pets or people who want to avoid salt-related damage to their vehicles or homes. Local company Chemical Solutions calls urea “one of the least toxic common deicers.” As with any fertilizer, however, high enough concentrations of urea can cause damage to plants. Urea begins to lose effectiveness when temperatures drop below 25 degrees Fahrenheit, making it a less suitable option for extremely cold days.
One concern about urea is that runoff could enter the water supply, where an excess of nitrogen could lead to algae growth in the spring. This can throw the water ecosystem out of balance. Therefore, it is important—not only with urea, but with any deicer—to avoid overusing the product.
Boston Building Resources offers a blend of urea and sand for ice and snow control. Urea makes it an effective deicer that is safe for plants, metal, and pets’ paws, while the sand provides traction for walking or driving. BBR’s ice melt should be used no more than one half pound (about 4/5 of a cup) per square yard of area. When used responsibly, our ice melt blend is an effective option for keeping surfaces safe.
A less common, but extremely effective, deicer is calcium chloride, which works in temperatures up to 35 degrees colder than salt—all the way down to minus 15 degrees Fahrenheit! While it deices quickly, calcium chloride can attract moisture, resulting in wet and slippery surfaces. Calcium chloride is also noncorrosive, making it safe for use on most surfaces, but it is still considered somewhat harmful to pets. The biggest disadvantage of calcium chloride is the relatively high price, which makes it a less attractive and realistic option for people who need a significant amount of deicer.
Although not readily available for retail purchase, potassium acetate is considered one of the most environmentally friendly options for deicers. In particular, potassium acetate is now the primary deicer used on airport runways, to prevent a large volume of runoff containing salt or urea. Acetate is generally used to prevent ice from forming on the runway to begin with rather than melting preexisting ice. As its prevalence as a deicer increases, potassium acetate may become more readily available in the future.
Whichever product you choose, the best way to ensure that your deicing isn’t causing environmental damage is to use it sparingly. Read the instructions on whatever deicer you choose, use a spreader when possible, and don’t exceed the recommended amount.
Other sources of information
- Material Data Safety Sheet on urea nitrogen
- Consumer Reports comparison chart of common ice melt products
- Meltsnow.com, for information on calcium chloride and acetate deicer