Melting Snow and Ice: Should You Pre-treat or Post-treat?

anti icing deicing ice melt jpg

Melting Snow & Ice: Should You Pre-treat or Post-treat?

Some snow crews work before bad weather hits by applying a solution that helps melt snow and ice on impact. Others wait for the weather to happen and then treat problem areas after the fact.

So, which is better?

The best crews use a combination of both. This article intends to equip you with the knowledge you need to apply the right method at the right time.

First, let’s review the two terms we will be using to discuss the different approaches:

Post-treating, also called deicing, is any process that removes snow and ice after it has accumulated. The most common method of de-icing is applying rock salt (sodium chloride) crystals. The salt crystals mix with the snow, creating a salt brine that melts precipitation by lowering its freezing point.

Pre-treating, also called anti-icing, is any snow and ice melting process that is applied to surfaces before the snow flies. Liquid deicing solutions are the most common form of pre-treating.

Is one better than the other?

Well, that depends. The short answer is that pre-treating works better than post-treating, but as mentioned before, an effective snow and ice management solution includes both strategies.

The long answer is, well, longer. Buckle up…

Advantages of pre-treating

Here are some advantages of pre-treating:

    1. Less salt: Pre-treating solutions (like liquid deicers) use only 20-25% of the amount of salt that is required to clear the same amount of snow that post-treating with a rock salt deicer needs.
      Less salt means:
      • less cost
      • more environmentally friendly approach, and
      • less clean up of gravel and sand in the spring.
    2. Works sooner: Pre-treating can work to create a barrier between snowfall and road surfaces, preventing ice build-up when vehicles drive over it.  Pre-treating also melts the first few millimeters of snow on contact before crews arrive, meaning that hazards and liabilities are reduced.  Compare that to salt crystals, which are applied only after snow and ice is built up and which need time to liquify before they have any melting effectiveness.
    3. More precise: Liquid solutions can be applied more precisely than salt crystals that tend to bounce and scatter to areas that do not need it, like grassy areas, tree wells, and flower beds—all which are negatively impacted by salt. The Michigan Department of Transportation learned that roughly 40% of rock salt spread on roads bounced off the roads and onto the shoulder. We make things even more precise through our GPS equipped pre-treating machines that ensure the manufacturer recommended amount of liquid deicer is dispensed for the speed of the machine doing the application.
    4. Easier snow removal: Anti-icing brings a site back to bare pavement conditions more quickly than other methods, resulting in fewer hazards throughout the winter season. This is because pre-treating creates a barrier layer between the ground and snow, like a non-stick frying pan, which makes the snow easier to remove because it does not bond as much.“Preventing a bond is critical. You get better coverage of a property or a surface with liquid. You have a bit more control over the liquid to a degree, depending on the equipment you use. If you’re using a spreader that’s flinging salt, you have to deal with this concept of bounce and scatter.”- Brian Birch, COO of the Snow & Ice Management Association (SIMA).
    5. Cheaper: Because liquid deicer uses less salt and has more precise application, it can be significantly cheaper than post-treating. However, crews are usually more strategic with the areas where salt crystals (post-treating) are applied, which means that pre-treating can be more expensive when not done properly.
    Fun fact: We have our own liquid deicer making plant, which brings down the cost of pre-treating even more for our clients.  See it in action below.

  1. When to post-treat insteadOK, with all those advantages of pre-treating, why post-treat at all?Pre-treating options fall down when applied in extreme cold (below -20°C) or during windstorms. In these conditions, they can actually do the opposite of what is desired. Instead of melting snow and ice, liquid deicer can freeze and create its own icy surfaces.Best of both worldsLiquid deicer is not the cure-all. It should be just one component of your overall snow and ice management solution. We recommend targeting specific problem spots with liquid deicer. For areas larger than 1-acre, total coverage can be cost-prohibitive. Instead, a post-treating sanding mix, or a pickle mix (gravel and rock salt combined), may be more cost effective. LECM works with you to make sure pre-treating and post-treating is done sensibly.Applying liquid deicer solution strategically can significantly reduce the cost of keeping high traffic or hazardous areas clear.Areas that require bare pavement, like 
    • high foot-traffic corridors,
    • busy sidewalks,
    • loading docks, and
    • sloped traffic surfaces
    are great candidates for pre-treating and reduce risks and challenges for pedestrians and drivers. Keeping these surfaces free from snow and ice can save headaches.SummaryPre-treating areas with liquid deicer before a snow event is more effective than applying ice melt or rock salt after the snow falls. However, in instances where the weather is too cold, or in areas that cannot be reached by liquid deicer equipment, post-treating is an effective option.