Though there are many different brands of commercially available ice melt for use in melting ice and snow, there are really only two major types. The first type contains some form of salt; these can be identified on the label as chloride. The other major type contains urea, which is often used in fertilizer and at higher concentrations can be used to more safely melt snow and ice.
Ice melt is a product designed for use in climates of extremely cold weather and typically comes in fairly large granules that can be sprinkled over an area of snow and ice. These products tend to work in a way similar to natural salt, which lowers the freezing point of water, thereby causing already frozen water in ice or snow to begin to melt. Rock salt itself is fairly expensive, and can be quite harsh on a variety of different surfaces and vegetation, so a number of alternative types of ice melt products have become increasingly available for use.
One of the most common types of ice melt products are those that include some form of salt, and these are typically identified by the word “chloride” on the packaging. Common salt varieties include potassium chloride, which only works at temperatures above 25° F (just above -4° C); sodium chloride, which works in temperatures as low as 10° F (just below -12° C); magnesium chloride, which works down to -22° F (-30° C); and calcium chloride, which can melt ice at -25° F (about -31° C). These salts can be very damaging to vegetation, however, and at temperatures below -25° F (-31° C), they will no longer prevent water from freezing. Ice melt brands that use these chemicals are fairly affordable, and these salts are often blended in ways unique to each brand.
The other common type of ice melt is a product that includes a chemical known as urea, which is a chemical compound found in mammalian urine. The urea used in the product is typically synthetic, however, and though urea is commonly used in fertilizer, it is usually found in higher concentrations in products designed to melt ice. Products that use urea can typically melt ice at temperatures at or above 20° F (about -6° C), but they can also be less harsh on concrete and similar surfaces. These products are often more expensive than those using salt, however, and they can still cause damage to vegetation and surfaces such as wood flooring or carpeting.