What are the main weaknesses of the existing UHMWPE ski base types? – Part V.

Fifth issue of the existing UHMWPE ski base types is their very low ability to bind gliding ski waxes and other gliding agents chemically.

How it works?

Chemical bonds between UHMWPE and wax-based gliding agents are very weak, chemical bonds between carbon black as main structural and reinforcement additiv in modern ski base types are extremelly weak. In other words: if applied on a ski base, wax-based gliding agents cannot rely on chemical bonds, they urgently need mechanical retention.

Mechanical retention is strongly depending 1. on available free spaces or cavities in both very top surface and in bulk material of the ski base, 2. on size and disponibility of these free spaces and cavities = they are avaibale in amorphous and transition areas only, many of them are occupied by soot and other additives), 3. on size and charakter of the wax molecules which need to get inside free spaces when base material is more flexible thanks to heat and get stuck there when base material cools down again, 4. on the level of intertwining of the molecular chain structures of both ski base material and wax-based gliding agents.

Maybe the last forth condition is the most significant one for how strong the final mechanical retention of waxes in the ski base is. At the same time this forth condition = the level of intertwining of the molecular chain structure of ski base material on the one side and ski wax substances on the other side is the most problematic and tricky one.

Why?

For wax-based gliding agents very strong dependency exist between hardness and strogness of intertwining on the one side and softness and weakness of intertwining on the other side. This very strong dependency is defined by the length and charakter of the molecular chains of wax-based gliding agents.

The longer and more branched the molecular chains of the wax-based gliding agents are, the stroger they can be intertwined with extremely long molecular chains of the ski base material (UHMWPE), thus, the stronger is their mechanical retention inside the ski base material.

The shorter and less branched the molecular chains of the wax-based gliding agents are, the weaker they can be intertwined with extremely long molecular chains of the ski base material (UHMWPE), thus, the weaker is their mechanical retention inside the ski base material.

At the same time the length and charakter of the molecular chains of wax-based gliding agents define their gliding properties.

The longer and more branched the molecular chains of the wax-based gliding agents are, the stroger they can be intertwined with extremely long molecular chains of the ski base material (UHMWPE), thus, the stronger is their mechanical retention inside the ski base material, the worse gliding properties.

The shorter and less branched the molecular chains of the wax-based gliding agents are, the weaker they can be intertwined with extremely long molecular chains of the ski base material (UHMWPE), thus, the weaker is their mechanical retention inside the ski base material, the better gliding properties.

Waxes with best gliding properties does not stick to ski base material, the better waxes stick to ski base material, the worse gliding properties they have. Good advice is better than gold.

How does the wax stick to the ski base? - part I.

It is common knowledge that ski bases are waxed. Many wax manufacturers offer liquid waxes where the wax is dissolved in a rapidly evaporating agent. With a sponge you just apply liquid solution of wax and solvent on the ski base and after the solvent evaporation your ski is ready to be used with improved gliding features!

Is it really true?

To answer this question, we need to understand how the wax sticks to the ski base. Does it stick by chemical bonds or by mechanical retention?

The way how waxes stick to the ski base depends especially on the type and features of the ski base. Cheaper extruded ski base types do not have NANO fibril structure to retain waxes mechanically, thus they need to stick to the ski base by chemical bonds only.

 

Chemical bonds are – however – very weak, thus the abrasion resistance of such a wax layer is very low. In other words: a wax layer – especially liquid wax layer – applied on the cheaper extruded ski base will wear off in several hundred meters or max. kilometers depending on snow conditions.

 

More expensive sintered ski base types have NANO fibril structure on the very top surface to retain waxes mechanically, thus waxes are mixed with the base material to a new layer consisting of both wax and ski base material.

 

Mechanically retained wax molecules are protected against abrasion forces, thus their life time is relatively good. Mechanical retention is – however – supported by heat, thus hot wax application is recommended here. Cold liquid wax application will hardy penetrate deep enough.

Conclusions

Waxes stick to cheap extruded ski base types by weak chemical bonds only with very low life time of wax coating. Waxes stick to more expensive sintered ski base types by mechanical retention with good life time. Liquid wax application seems to be waste of money in both cases.