How Rock Salt Actually Melts Ice

3 min read · Thames Valley Snow, London, Ontario

Salt needs water to start

Dry salt crystals sitting on dry ice do very little. Salt only begins to work once it dissolves, and to dissolve it needs a small amount of liquid. On most winter days there is enough moisture on the surface, from a thin melt layer, humidity or friction from tires and feet, for the crystals to start forming brine. That brine spreads, melts more ice, dissolves more salt and the process keeps going.

This is why you often see small holes or pits form under each crystal first, then spread outward until the ice breaks up.

Why it slows down in deep cold

Saltwater freezes at a lower temperature than fresh water, but the effect has a limit. As the temperature drops, salt takes longer to work and needs much more product to do the same job. In practical terms, ordinary rock salt (sodium chloride) becomes slow and unreliable somewhere around -10°C, especially on shaded surfaces. Other de-icers, such as calcium chloride or magnesium chloride blends, keep working at colder temperatures, which is why they are often used on very cold days or on steps.

Why more salt is not better

Throwing extra salt on a driveway rarely speeds things up and causes real problems:

• Salt residue is tracked into homes and onto floors.
• Excess salt runs off into lawns, gardens and storm drains.
• Salt is hard on concrete, especially newer or poorly sealed surfaces.
• It can irritate pets' paws.

Applying the right amount at the right time, and clearing snow first, does far more than heavy spreading.

Timing matters as much as product

Salt works best when it goes down on a clean surface before ice bonds firmly, or right after plowing so it is not wasted melting snow that could have been pushed away. Applied before freezing rain or an evening refreeze, a little salt stops ice from bonding to the pavement in the first place, which makes everything easier to clear. When temperatures are expected to be very low, sand can add traction, although it does not melt anything.

How our seasonal service handles it

Our seasonal plans run from December 1 to March 31. Clearing is automatic every time 5 cm or more falls, so you never need to call or book a visit. In long storms we come back for return visits, and the City windrow at the end of your driveway is cleared as part of the service. Before the season starts we mark your edges, steps and drains so they can be found under snow. After every visit you get a timestamped photo. We are fully insured with $2,000,000 in liability coverage and registered with WSIB. Seasonal salting is available for $175 plus HST and includes freezing rain and refreeze visits, and seniors and front-line workers save 5% on seasonal plans. Prices are fixed for the season: single or 1.5-car driveways are $650 to $725, doubles are $815, and three-car, paver or stamped driveways are $1,050, all plus HST. We measure your property from City of London maps and aerial imagery and send a fixed quote within one business day. A 30% deposit reserves your spot, with the balance due before December 1.

Want this handled for you this winter? Request a free quote and we will measure your property and send a fixed price within one business day, or call or text (548) 888-8702. You can also read more about salting and ice control and residential snow removal.

What's included… and what's extra

A Thames Valley Snow seasonal residential plan starts from $650 for a standard driveway. It covers clearing the driveway every time snowfall reaches the trigger depth in your agreement, plus the windrow the city plow leaves at the end of the driveway. Larger driveways are priced on our snow removal prices page.

Popular add-ons, priced per season: walkway and steps $150–175, salting $175, priority service $125, pet-safe salt $120, driveway extension $95 and city sidewalk clearing $90. Add only what your property needs; everything is listed on the quote so there are no surprises. Get your fixed price or call or text (548) 888-8702.