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Wax after salting

post #1 of 16
Thread Starter 
What temperature wax should you use if you know the ski run will be salted to prevent the snow melting ?
Thanks
post #2 of 16
Glacier Wax

http://www.holmenkol.us/cartproducts...sstat=&ref=401

In general though, you use a harder wax to account for the higher abrasiveness of salted snow.
post #3 of 16
Can someone (physicsman, perhaps?) explain the physics of salting the race course? Adding salt to a solution will depress the melting point. That is why they spread salt on the roads to keep them from icing up. SO how does that keep the snow from melting on the race course? I would think that if the melting point is lower, and the temperature is higher, the snow will melt even more easily! I have skied on a salted course (spring race camp for non-racers in May at A-Basin), and it kept the snow in great condition, but I cannot understand why. [This illustrates why physics was my worst subject in college, and why the only physics I understand is about gasses and fluid dynamics (a necessity for my line of work).]
post #4 of 16
OK I will be bold and give it a guess. It does seem, on the surface, to be counter intuitive so I wouldn't feel too bad.

I think the cooling effect is derived from the melting of the surface snow. The snow-salt mixture needs energy (heat) to melt and it would draw it from its surroundings, the air above it and the snow pack below. The drawing of heat cools the snow. So even though there would be surface water the bulk of the snow is cooled.

The same thing happens with evaporation of water, to go from a liquid to a gas, energy is drawn from the bulk water. Steam (water vapor) leaves and the remaining water is cooled.
post #5 of 16
Kind of related to making ice cream I would think. I've also heard them say they were using urea (EWWW).
post #6 of 16
Mostly they use fertilizer now. Hot scraping becomes very important after skiing on treated snow.
post #7 of 16
Quote:
What temperature wax should you use if you know the ski run will be salted to prevent the snow melting ?
Thanks
Dominator Zoom which is an all temp type of wax. Not real expensive and tends to be a pretty hard wax considering how well it works in summer temps. The hardness helps protect the base a bit. It is important to use the rinse off spigot at the base; then wax daily if you can for summer salt (fertilizer). The best thing is to have summer skis to use on the snowfield so as not to sacrifice your good ones. Good winter skis eventually become summer salt skis then eventually become rock skis. Then you cut em up and make a ski bench furniture set?

- Fossil
post #8 of 16
Quote:
Originally Posted by dp
Adding salt to a solution will depress the melting point.
Once it is dissolved. The trick is the process of forming the solution.

Heat of solution is the term for the overall energy total of:

A) the heat/energy required to break the bonds of the compound you wish to dissolve
B) the heat/energy released through forming bonds with the solvent (water).

Fun things happen if you select the proper compounds so that A > B; the overall reaction is endothermic, taking heat from the environment.

"Environment" in the case of snow is most directly the free liquid water present. Further fun things happen if the endothermic heat of solution exceeds the heat of fusion of the water.
post #9 of 16
Can anybody post the "non-engineering" version of how salt/fertilzer firms up the snow on a race course, please?
post #10 of 16
Actually, that was more physical chemistry than engineering

As I mentioned above, for anything to change phase (go from solid to liquid, or liquid to gas) it needs energy. The treated snow, takes that energy from the snow pack in the form of heat, thus cooling it down.

.
post #11 of 16
Quote:
Originally Posted by RACEWAXdotCOM
Actually, that was more physical chemistry than engineering

As I mentioned above, for anything to change phase (go from solid to liquid, or liquid to gas) it needs energy. The treated snow, takes that energy from the snow pack in the form of heat, thus cooling it down.

.
Then where does the heat/liquid go?
post #12 of 16
Into breaking the chemical bonds between elements of the salt/fertiliser compound that keep it a solid at room temperature.

- A little bit of snow melts,
- the liquid is immediately faced with the immense chore of dissolving the salt,
- and robs itself and other liquid around it of heat to do so.
- without that heat, liquid refreezes.

Of course, the result isn't pure water ice.
post #13 of 16
A chemical reaction can be exothermic (heat is produced) or endothermic (heat is absorbed). Generally, salts dissolve endothermically. Ammonium nitrate is one that's kind of well known for that, though I think regular table salt also dissolves endothermically.

One kind of weird thing is that if the reaction occurs spontaneously and absorbs heat from its surroundings (i.e. reduces entropy in the world outside the reaction), it must necessarily increase entropy in the solution itself even more (by breaking up the ordered lattice of atoms in a salt).
post #14 of 16

Is there a ready numerical solution

Quote:
Originally Posted by sjjohnston
it must necessarily increase entropy in the solution itself even more (by breaking up the ordered lattice of atoms in a salt).
To "what part of the solution must trickle off?"
post #15 of 16
Quote:
Originally Posted by comprex
Into breaking the chemical bonds between elements of the salt/fertiliser compound that keep it a solid at room temperature.

- A little bit of snow melts,
- the liquid is immediately faced with the immense chore of dissolving the salt,
- and robs itself and other liquid around it of heat to do so.
- without that heat, liquid refreezes.

Of course, the result isn't pure water ice.
Thanks. I can follow that.
Now why doesn't the same thing happen on the road when they salt it (why doesn't it refeeze)? The road salt on the road seems to stay liquid and melt new snow that hits it. Is it just because they put on a larger amount of salt per square foot?
post #16 of 16
Quote:
Originally Posted by NE1
Is it just because they put on a larger amount of salt per square foot?
Too much water per undissolved salt.
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