On icy days, you want to keep your sidewalks clear. But with so many products out there, what is the best way to melt that ice without damaging what is underneath it?

Experts say you have to be more sophisticated these days than to use salt. You also need to think about what the temperature is at the time you use it.

If you have a concrete sidewalk covered with ice, the best ice-melting chemical is pure calcium. Calcium chloride will work below 0 degrees, while rock salt doesn't work much below freezing.

Rock salt is a lot cheaper, but Dave Ralph of Marchwood Hardware in Uwchlan, Pa., says that the calcium will do a better job.

Ralph said they started the day with three pallets of rock salt and calcium and ran out in the first couple of hours.

The members of the ambulance corps had a lot of ice around their driveway and decided to opt for calcium chloride, since the temperatures were still so low.

Another problem with rock salt is that it can damage concrete, asphalt and plants.

But experts say that salt or calcium chloride alone will not melt the ice. It needs sun, warmth and a lot of traffic to crunch the chemicals in and get the chemicals working.

According to the University of Michigan's Occupational Safety and Environmental Health Department, there are seven chemicals or products that are useful in melting ice:

Sodium Chloride (rock salt)

Calcium Magnesium

Magnesium Chloride

Calcium Chloride

Potassium Acetate

Ice Ban

Sand

Each substance has a different effect on the environment and a specific temperature where it can be used. Click here for the specific guidelines.