1.8 First Reservoir: The Macroscopic Wax Layer Above the Surface
The first and most clearly visible reservoir consists of wax that remains as a continuous layer above the original ski-base surface after ironing.
Its thickness may be locally relatively high, particularly where a large amount of wax has been applied or where the wax has not been distributed uniformly by the iron.
Wax filling the deeper parts of the ground structure also belongs to this category.
This is not wax absorbed within the polymer matrix. It is wax lying above the local UHMWPE surface and mechanically filling:
- grooves,
- depressions,
- grinding marks,
- open surface defects,
- spaces between protruding fibrils.
This layer is largely a technological surplus.
If it remained on the ski base, it would cover or significantly restrict the function of the ground structure. It could increase the real contact area, impair the removal of water and contaminants, and form a soft surface susceptible to the mechanical retention of dirt.
It is therefore intended to be removed primarily with a plastic scraper and by subsequent brushing.
The macroscopic reservoir is not equally thick everywhere. Its thickness varies along the X- and Y-axes according to the local topography, the amount of applied wax, the direction in which the iron was moved, and the geometry of the structure.
1.9 Second Reservoir: A Thin Wax Film Within the Surface Microstructure
After the macroscopic surplus has been removed, a very thin wax layer remains mechanically and adhesively bonded to the surface.
It is located in particular:
- on the peaks and walls of the ground structure,
- in fine scratches,
- between fibrils,
- in surface defects,
- in open microscopic depressions,
- at interfaces between differently oriented UHMWPE regions,
- around certain additive particles and agglomerates.
This second reservoir is no longer merely a thick technological surplus.
It may contribute significantly to the resulting:
- frictional properties,
- wettability,
- surface energy,
- resistance to contamination,
- initial glide performance.
It is, however, difficult to define precisely which part of this film is still excessive and which part is already functional.
Brushing must remove wax that blocks the ground structure, but it should not automatically mean removing all wax from the peaks, walls, and microroughness of the surface.
The second reservoir is the most vulnerable to excessive brushing because it is directly mechanically accessible to the tips and side surfaces of the brush filaments.
1.10 Third Reservoir: Wax Within the Uppermost Polymer Zone
The third reservoir consists of wax that has penetrated beneath the geometric surface into the uppermost part of the UHMWPE during heating.
This wax is not stored in ordinary open pores. It is located primarily:
- in surface-accessible amorphous regions,
- in partially accessible transitional regions,
- at interphase boundaries,
- in manufacturing and surface defects,
- in microcracks,
- in areas disturbed by grinding.
Its concentration is not uniform either across the surface or with depth.
Along the X- and Y-axes, regions capable of absorbing relatively more wax alternate with areas whose surfaces consist predominantly of crystalline material or additive particles and therefore have a very low absorption capacity.
Along the Z-axis, the wax concentration is likely to decrease rapidly from the surface into the material.
This reservoir is not normally accessible to the scraper or brush as free wax. A steel filament cannot simply “comb” it out of undamaged polymer.
It may, however, remove it indirectly if the filament begins mechanically removing the uppermost UHMWPE layer in which the wax is stored.
Even a very small loss of polymer may be significant in this respect if most of the absorbed wax is concentrated within the first few hundred nanometres of the surface.