What is black ice--and why is it slippery?

  • Black ice is relatively smooth, hard, and clear.
  • Packed snow eventually turns to black ice, especially when it rains, or when there's a thaw, followed by freeze.
  • You must completely remove packed snow if you want to prevent ice buildup.
  • Black ice is most slippery when water is present.   Then it can be very dangerous.  Applying sand to ice greatly improves traction.
Black ice on the roads is what sends cars spinning out of control.  On sidewalks with black ice, pedestrians fall without warning.  So what is "black ice," and how does it form?

This "black ice" formed by freezing of meltwater.  It looks bright because it's reflecting the sunset.

Black ice is no different from ordinary ice--except that it's more compact and has a smoother surface.  Here's how snow turns to black ice.


How to prevent sidewalk ice--without salt

Use the sun instead of salt!

Key ideas...
  • Prevent packing during snowfall by clearing a narrow lane--people walk there, preventing packing elsewhere.
  • Clear to full width by noon of the day following snowfall.
  • Scrape remaining packed snow so light gets through to the pavement.
  • Let the sun evaporate the rest (ice can evaporate without melting).
  • Touch up daily--before leaving for work.
Removing packed snow prevents ice


Clear sidewalk snow without salt

Prevent snow from packing down...
because packed snow turns to hard ice in a few days.

Snow blowers make things worse, because they leave a layer of packed snow.

Use a shovel with a sharp edge (or an ice scraper) to remove packed snow. The sooner you remove it, the less the ice sticks to pavement.

Shovel a narrow lane as soon as you can. People will walk there, and won't pack snow on the unshoveled portion.

Now use solar power to melt the rest! 
To disappear, ice (or packed snow) does not need to melt. It can go directly from solid to water vapor, even at temperatures below zero! It's called "sublimation."

Ice does require energy to vanish without melting. You have to scrape the snow thin enough so light energy will penetrate to the pavement. Even with thin clouds on cold days, enough sunlight penetrates to make a difference. The ice will disappear in a few days, depending on temperature and sun. Touch it up before you leave for work... the sun will do the rest.

To prevent icy patches from forming when it warms up, clear to the edge of the sidewalk between snowfalls. This way, any meltwater sinks into the ground at the pavement's edge. You don't get icy puddles on the sidewalk.

With more pavement exposed, the sidewalk area gets warmer, helping to prevent new ice--and the next snowfall is easier if the whole sidewalk has been cleared.

You have to clear your sidewalk, but you don't have to shovel your driveway, at least not right away.

Work in stages to avoid fatigue, resting between. First the central strip of the sidewalk. Then scrape packed snow. Then enlarge the width of the path. Finally, clear to the grass and chip any remaining ice.

Check the weather report. If it's going to warm up, no worry to clear snow. If a long period of cold weather is coming, be careful to prevent packed snow. Salt doesn't melt ice at temperatures below about 15F, but the sun does!

Even on hills or steps, you don't need salt. Sand works very well. You can find it in city barrels at street corners. You can buy Yaktrax to make your shoes slip-proof.

Hope this helps! HAPPY SOLAR SHOVELING !