WHY FRESH POWDER SNOW DOES NOT GLIDE AT ALL?

 Why skiing on fresh powder snow is so challenging?

Fresh powder snow or freshly fallen snow at temperatures below zero and low relative air humidity is extremely challenging for gliding and low friction coeficients.

Why?

Powder snow is cristalic, in other words: individual snow flakes keep their original sharp shape. If they brake during slope or track preparation by pisten bully new sharp edges, tips and forms arise. 

Powder snow contains a high share of air resulting in surface changes of the snow if skis are gliding over it. Such surface changes lead to brittle deformations of cristals again.

Result:

Sharp, hard, brittle snow cristals which brake and do not connect to snow pack. The surface of the snow is extremely fragmented - similar to a stone field resulting in few and very small contact points between snow and ski base surface.

Few and very small contact points between snow and ski base surface lead to high pressure in the contact spots. Small contact points, high pressure, sharp / hard and brittle cristals create a combination responsible for very high friction between snow and ski base surface.

The lower the temperature, the higher the hardness of snow cristals. At a certain point (for normal ski base types = HDPE at ca. -10 degrees C, for competition ski base types = UHMWPE at ca. - 15 degrees C) the hardness of sharp cristals exceeds the hardness of the ski base resulting in ski base plowing effect.

Under such conditions you will not want to ski...

Conclusions:

If fresh powder snow is fallen deep below zero, stay at home instead of skiing! If you need to ski in fresh powder snow on a slope, protect your ski base with a hard and hot applied wax coating. If you are a nordic skier, protect your ski base and try to improve the gliding properties the best possible way otherwise your trip can turn in a nightmare - apply hard protecting wax hot with a hot powder coating and liquid speeder!

WHY MAN-MADE SHOW IS EXTREMELY ABRASIVE?

 Why Man-Made Snow is Extremely Abrasive?

You noticed for sure that the so called man-made snow is much more abrasive than the natural types of snow. Man-made snow is used in alpine resorts (on ski slopes) more often than in nordic areas (XC tracks) but currently it is the most common snow type especially in lower regions.

Especially if the temperature is deep under zero, the man-made snow is so hard and so abrasive that you can have the feeling “it is cutting into the ski base”... And your feeling is almost literally correct.

Man-made snow consists of ice grains which are small, rounded and extremely hard. Thanks to small size or diamter of individual ice grains the man-made snow is also extremely compact and dense - it contains small share of air compared to natural types of snow. Shortly after production man-made snow is moist to wet even if it is freezing.

What’s the reason why man-made snow is so abrasive?

The correct answer is hidden in the hardness. We mentioned that individual ice grains of man-made snow are small, rounded and extremly hard. Especially the extreme hardness of the snow grains connected with the very compact surface of the snow pack are the main reasons why man-made snow is much more abrasive than natural types of snow.

Why are the ice grains of man-made snow so hard?

The extreme hardness of ice grains of man-made snow is caused by freezing direction which is opposite to natural snow types. 

Natural snow types freeze from the center to the edges. Air humidity condenses on a snow flake nucleus (most often a dust or dirt particle) and starts to develop from the center to the edges in various forms and shapes.

In case of man-made snow a small water droplet is flying out of the snow cannon and meets the cold air, at the moment as the water droplet gets in touch with the cold air, a thin ice shell develops on the outside perimeter of the water droplet, while the middle remains filled with water. Ice grains of man-made snow freeze from the outside to the center gradually. Liquid centre is locked in a ice shell.

If water changes from liquid to solid state its volume increases slightly. Water locked in a ice shell cannot increase the volume resulting in the increase of density. Increased density means increased hardness.

Increased density = increased hardness of ice grains of man-made snow is the main reason why man-made snow is so extremely abrasive.

HOW TO SELECT THE CORRECT SKI BASE?

 How to Select the Correct Ski Base?

Most of normal skiers - does not matter if alpin skiers or nordic skiers - know the black ski bases which are the standard in the last ca. 30 years.

The black colour of the ski base is caused by soot which is added directly to the ski base material.

Why SOOT and what are the main advantages of the black ski bases?

• soot is cheap
• soot has the correct NANO size
• soot is a type of dry lubricant
• soot as NANO particles is hard
• soot is conductive
• soot improves grinding
• soot can help to repell dirt 

In other words:

• black ski bases are usually harder than the transparent ones
• black ski bases are more suitable for colder conditions due to higher hardness and lower electrostatic charge
• black ski bases can be grinded more efectively and precisely
• black ski bases can repell dirt better that the transparent ones

Special advantage of black ski bases:

If they wear due to intensive using especially on abrasive cold or man-made snow types, they change the surface colour to grey or white gradually. This is a clear sign that they need to be maintained / serviced.

Black ski bases have also some disadvantages

• they abrosb normally less wax than the transparent ski bases
• they can be less hydrophobic or water-repellent than the transparent ski bases
• dirt which is normally dark is hardly visible on the black surface

Conclusions

Black ski bases perform very well especially in cold conditions. They are more universal than the transparent ski bases. In wet and very wet conditions hydrophobity of black ski bases needs to be improved by water-repelling waxes. For normal alpin and nordic skiers the black ski base is usually the right choise.