Calcium Chloride Versus Magnesium Chloride in Ice Melter Products

This article compares the two most effective chlorides found in quality ice melter products.

Freeze Points of Calcium Chloride and Magnesium Chloride

Calcium chloride’s (CaCl2) eutectic temperature is -51˚C (-60˚F.).
Magnesium Chloride’s (MgCl2) eutectic temperature is -33˚C (-28˚F). But, its melting rate drops to a low level well before it reaches this temperature and crystallizes.

Magnesium Sulfate Crystallization Creates Problems Within Equipment

The effectiveness of Magnesium Chloride is often limited by the presence of magnesium sulfate as an impurity. Magnesium sulfate crystallizes between -18˚C (0˚F) and -20.5˚C (5˚F) and causes sludge in tanks, clogging of spray nozzles and transfer pumps. By contrast, a 32% Calcium Chloride solution, the most commonly used concentration in winter, does not form crystals within its working range.

Calcium Chloride vs Magnesium for Ice Melting, De-Icing Capacity and Ice Penetration

Calcium chloride melts more ice at low temperatures. At -10˚C (14˚F), a 32% Calcium Chloride liquid melts 27% more ice than Magnesium Chloride. At -20˚C (-4˚F), 32% Calcium Chloride melts 94% more ice than Magnesium Chloride.

The Midwest Research Institute study (based on FHWA, Strategic Highway Research Board test methods) evaluated ice penetration of calcium chloride vs magnesium chloride. The study found that at -7˚C (20˚F), CaCl2 has 22% more penetration after 10 minutes and 38% after 30 minutes than MgCl2. At -15˚C (5˚F), CaCl2 had penetrated 58% more ice after 30 minutes.

Application Rate Comparison of Calcium Chloride and Magnesium Chloride

Calcium chloride has a lower application rate compared to magnesium chloride because calcium chloride has higher ice melting capacity and faster ice penetration. Given their relative commercial strengths and active chemical purity, 50% to 100% more MgCl2 than CaCl2 is usually required to remove equal amounts of snow and ice.

When applied as liquids, two parts of CaCl2 does more work in less time than three parts MgCl2.

Some Effects of Magnesium Chloride and Calcium Chloride on the Environment

The Ministry of the Environment in British Columbia found that CaCl2 has significantly less toxicity than MgCl2 in bioassay tests on rainbow trout and the water flea daphnia. For instance, rainbow trout, which represent the high end of the food chain, were five times more sensitive to MgCl2 than to CaCl2.

Scrub n Shine sells a high quality, perfect blend of four chlorides. Contact us to learn more!