1.11 The Boundaries Between the Individual Reservoirs Are Not Sharp
The three reservoirs described above form a useful working model, not three perfectly separated layers.
In reality, continuous transitions exist between them.
Wax filling a deeper groove in the ground structure is geometrically located above the polymer surface, but it may simultaneously be retained very strongly by mechanical interlocking.
At some locations, the thin surface film may be only adsorbed, while in a neighbouring amorphous region it may already partly penetrate beneath the geometric surface.
A microcrack or an interphase gap around an additive particle may simultaneously function as:
- a surface depression,
- a mechanical wax reservoir,
- an entry pathway into the polymer surface zone.
At different locations on the ski base, all three reservoirs may therefore coexist in different proportions.
1.12 Practical Importance of Dividing the Wax into Three Reservoirs
Dividing the wax into three reservoirs makes it possible to define the objective of scraping and brushing more precisely.
First reservoir
The macroscopic surplus should be removed almost completely. Leaving it in place would cover the structure and impair the function of the surface.
Second reservoir
The thin film should be reduced selectively. The ground structure must be opened and loose or excessively thick residues removed, but it is not self-evident that the optimum objective is to remove all wax from every mechanically accessible part of the surface.
Third reservoir
The wax within the polymer surface zone should remain preserved. Its removal is not part of the desired cleaning of the ski base, but rather a possible secondary consequence of abrasion of the UHMWPE itself.
The fundamental question in brushing is therefore not merely:
How quickly does the brush open the ground structure?
An equally important question is:
At what point does the brush stop removing technological surplus and begin reducing the functional film or the wax-enriched polymer surface zone itself?
This question will be examined in the following chapters dealing with manual and rotary steel brushes.