Anti-icing and de-icing are the two halves of commercial snow removal in Seattle, and they are often confused. Knowing which is which tells you what to ask for in a contract and when the work should happen.
Pre-Treatment and Ice Removal: The Short Version
Anti-icing is applied before ice forms. De-icing is applied after it has. One prevents the bond between ice and pavement. The other breaks a bond that already exists.
What anti-icing does
Liquid brine is sprayed on dry or damp pavement ahead of a forecast freeze. As the water on the surface cools, the brine lowers its freezing point, so ice either does not form or forms weakly and releases easily. Because the product is a liquid applied in measured amounts, it uses less salt than spreading granules after the fact.
What de-icing does
De-icing uses rock salt, calcium chloride, magnesium chloride or a liquid blend to melt ice that is already on the surface. It works from the top down, so a thick bonded layer takes longer and more product. De-icing is the right response when pre-treatment was not possible or the storm outran it.
Which One Does a Seattle Property Need?
Most need both. Western Washington sees freezing rain and cold snaps on wet pavement more often than deep snow, so the pavement can glaze over without a single flake sticking. A contract built around plowing alone does very little in that situation.
- Forecast freeze, no snow: anti-icing, and de-icing if ice appears anyway.
- Snow over cold pavement: anti-icing first, then plowing, then de-icing on what the plow leaves.
- Slopes, ramps and shaded corners: repeat applications, since these refreeze first.
Limits to Know About
Brine is less effective when it is washed off by heavy rain before the freeze, and every salt-based product slows down as pavement temperature drops. A good vendor checks pavement temperature, not just air temperature, and tells you when a second pass is needed. Ask for the product, the time and the area treated to be logged each visit.
Whichever service leads, the price depends on the number of visits and the trigger you set. The commercial snow removal cost in Seattle guide explains what moves a bid up or down, and how to compare vendors fairly.
If you are deciding how to buy the service, per-event vs seasonal snow removal contracts covers the tradeoffs.