What are the main weaknesses of waxes? Part no. II – wax softness

Waxes are normally soft, much softer than the material of the ski base. Even if ski wax manufacturers try to mix hard waxes for abrasive and aggressive snow conditions, waxes are normally softer than the ski base itself.

 

If softer waxes are mixed with the ski base material in the top surface of the ski base creating the mixture called gliding surface, the result is always softer surface of the ski base or softening of the ski base surface by adding the wax.

 

The hardest waxes offered currently on the ski wax market like Toko X-Cold Powder / Blue X-Cold, Holmenkol Ultra Base Cold, Swix CHX4 / HSX4 / PS4 (cold powder blue/green series), Maplus Race Base Cold – reach the hardness 40 to 50 shore D which is still below the hardness of the ski base which is normally 65 shore D.

 

If we consider that the wax absorbing capacity in cavities inside molecular structure of a ski base is ca. 5 to 30 % of the thin top layer of the ski base, we can say that on the surface amounting to max. 255 cm2 and min. 38 cm2 of the total 765 cm2 the hardness is reduced by ca. 23 to 38 per cent.

 

If we consider that especially the hardness is the most important factor influencing the gliding qualities or friction especially in cold, hard and abrasive snow conditions, then it could mean that wax application under these conditions is contra-effective.

 

Fortunately for ski wax manufacturers, the question is not as straightforward as it might seem at first glance. It is true that the application of soft waxes reduces the entire hardness at least in the extent where wax molecules are accommodated inside the ski base material. On the other side ski base is protected and intermolecular bonds between ski base surface and snow surface can be blocked thanks to wax application.

 

We need to apply waxes also under cold, hard and abrasive snow conditions to protect the ski base and block intermolecular bonds. At the same time wax application will always decrease the ski base hardness. Especially the hardness is the most important factor influencing the gliding in cold and hard snow conditions.

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 crystalline, 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 crystalls again.

Result:

Sharp, hard, brittle snow crystalls 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 crystalls create a combination responsible for very high friction between snow and ski base surface.

The lower the temperature, the higher the hardness of snow crystalls. 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 crystalls 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.