On Fri, 07 Feb 2014 03:38:44 -0500, wrote:

On Thu, 06 Feb 2014 22:02:21 -0500, wrote:
Lately they have been using Brine around the NY, NJ area.
I've heard that but brine is just water and salt. Not sure what the
advantage of that when it's too cold for salt to work at all.

Can't say what type of salt they've been using, but here in Toronto
it's been as cold as -30°F lately and it does work as long as the snow
is not excessively deep.

Sodium salt will not lower the freezing point of water much below 0F
(the original set point for the Fahrenheit scale) and more is not
better. The eutectic point for Sodium brine is -6F and the curves
slope up quite fast on both sides. The eutectic point of Calcium
brine is -60F but the slope of its density to temperature curves are
even steeper. Add either too much salt (Sodium or Calcium) or too
little (or it melts ice) and the freezing temperature goes up quickly.

When I was in Vermont, I found the Calcium worked much better because,
unlike Sodium salt the pellets melted pits in the ice at just about
any temperature. The pits or holes were good traction, even if it
refroze. Calcium also doesn't track in the house and destroy cars.
It's *lot* more expensive, though.