Sunday, January 2, 2011

Slippy Slidy Ice

Ice is slippery because of the way the ice crystals on the surface behave. Tiny ice particles (molecules) on the surface move back and forth very fast. This constant vibration makes the top layer of ice crystals act like a thin liquid, reducing friction between an object and the ice. Great for hockey pucks. Not so good for people walking on a sidewalk.

The colder it gets, the stickier ice gets. That means there’s more friction between an object and the surface of the ice. But the highway departments in our area don’t wait for the temperature to drop. Snowplows head out at all hours of the night spreading a mixture of sand and salt to increase friction – and help melt the ice on roads.

Up on our hill we spread wood ashes on the road. Not only do they give traction, but if it’s a sunny day the areas covered by the dark ashes melt faster than the ice without ashes. We sprinkle sand or kitty litter on the steps to our house.

What can you use to increase the friction – lower the slipperiness – of ice on your driveway?

First you need an ice patch to experiment with. Then try sprinkling different things across the surface to help your feet get a better grip. If you have some old beets from the garden, try beet juice – some communities are using beet juice instead of salt to help melt ice.

You also need a way to test slipperiness. Find something that slides across ice well, such as a hockey puck or flat-bottomed microwave container filled with dry beans. Now figure out how you can launch it across a patch of ice so that each test is the same. You might create a short ramp and let your puck slide down the ramp and onto the ice. Or you might devise a slingshot that launches the puck across the ice (make sure you pull it back to the same launch line each time). You also need a way to mark where the puck stops.

Test your experimental design a few times with nothing on the ice, and then sprinkle your “slip-stopper” on the ice and see how far your puck slides.


  1. Hi,
    I just saw your site from a link to mine and I checked. I love your post! It's great see you blogging about science. You list a great group.

  2. Congratulations on starting this blog! I came via NF Monday and love the sound of what you intend to do here. I'll definitely be checking back. Yesterday I was watching a BBC documentary about life in Greenland and I saw some amazing (sea) ice - really rubbery, almost like jelly. I've never seen anything like that before and would love to find out more about it.