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SKI GLIDE PHYSICS · RESEARCH SERIES

Why Ski Base Matters

PART 2 OF 2

Why Ski Base Matters – Part No. 2

What Actually Touches the Snow?

At the very beginning of sliding, assuming a freshly prepared and fully waxed ski base, the ski-base material itself may have little or no direct contact with the snow.

Instead, the initial contact takes place primarily between the snow surface and the additionally applied wax and coating layers. During the first several hundred metres, the outermost contact material may be a topcoat or a so-called speeder.

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SKI GLIDE PHYSICS · RESEARCH SERIES

Why Ski Base Matters

PART 1 OF 2

Why Ski Base Matters – Part No. 1

If ski waxes and surface coatings worked exactly as they are often presented to work—that is, if they formed a continuous layer covering the entire ski-base surface, regardless of how complex the structure pattern is, and if this layer survived for several tens of kilometres—then the ski-base material itself should matter very little during a race.

Under such conditions, the ski base should hardly ever come into direct contact with the snow. The actual sliding interface would be formed primarily between the snow surface and the wax/coating layer.

In reality, however, the sliding interface and the associated wear processes are considerably more complex.

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SKI GLIDE PHYSICS · FIELD TESTING

Liquid Ski Gliders: Wax Base vs. ISANTIN Coating

GLIDE PERFORMANCE & DURABILITY

Liquid Ski Gliders: Wax Base vs. ISANTIN Coating – Glide Performance and Durability

Does the performance of a liquid ski glider depend on the underlying base layer?

We compared complex liquid glide products, often referred to as topcoats or speeders, applied over two different preparation systems: a conventional wax base and an ISANTIN coating.

The initial glide performance was similar in both cases. However, after repeated runs, the liquid gliders applied over the conventional wax base retained their performance more consistently than those applied over ISANTIN.

Ski Wax Removal: Three Wax Reservoirs and Brushing – Part 5

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WAXING & SURFACE TREATMENTS · RESEARCH SERIES

Wax Layers & Ski Base Preparation

PART 5 OF 5

 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.

Ski Wax Reservoirs: Surface Films and UHMWPE Absorption – Part 4

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WAXING & SURFACE TREATMENTS · RESEARCH SERIES

Wax Layers & Ski Base Preparation

PART 4 OF 5

 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.

How Ski Base Additives Affect Wax Absorption and Penetration – Part 3

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WAXING & SURFACE TREATMENTS · RESEARCH SERIES

Wax Layers & Ski Base Preparation

PART 3 OF 5

 1.6 Effect of Additives on the Ski Base’s Capacity to Absorb Wax

Various additives and solid lubricants are commonly incorporated into UHMWPE intended for ski bases, including carbon black, graphite, and other carbon-based materials. The use of carbon particles and solid lubricants in ski-base materials is well documented in the technical literature.

How Does UHMWPE Ski Base Material Absorb Wax? – Part 2

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WAXING & SURFACE TREATMENTS · RESEARCH SERIES

Wax Layers & Ski Base Preparation

PART 2 OF 5

 1.3 Which Regions Can Absorb Wax

Under normal conditions, wax molecules cannot freely penetrate perfectly ordered crystalline regions of UHMWPE.

In the crystalline phase, polymer chains are tightly packed and there is insufficient free volume between them for the easy diffusion of paraffin-wax molecules. Crystalline regions therefore represent effectively closed or very poorly accessible parts of the material with respect to wax penetration.

Ski Base Structure and Wax Reservoirs – Part 1

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WAXING & SURFACE TREATMENTS · RESEARCH SERIES

Wax Layers & Ski Base Preparation

PART 1 OF 5

Hand or Rotary Brush – That Is the Question?

Service People Version – Understanding Ski Wax Layers

Ski waxing is often presented as a relatively straightforward process: apply wax, allow it to cool, scrape off the excess and finish the ski base with a hand brush or a rotary brush.

But what exactly are we removing during scraping and brushing? Where does the wax actually remain? And how do the properties of the ski base material and its structured surface influence the final result?

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SKI PREPARATION · RESEARCH SERIES

Hand or Rotary Brush?

PART II OF II

Hand or Rotary Brush? Part II – How Rotary Steel Brushes Remove Ski Wax

In Part I, we examined the three principal types of wax reservoirs and the relatively slow, cumulative mechanical action of a hand-held steel brush.

Rotary steel brushes serve the same general purpose, but their construction, wire stiffness and operating speed produce substantially different contact conditions.

The following analysis examines these differences and compares the practical characteristics of both brushing methods.

Ski Base Stiffness and Structure Stability on Wet Snow – Part 2

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SKI GLIDE PHYSICS · RESEARCH SERIES

Ski Base Material and Structure Quality

PART 2 OF 2

 The Importance of Dimensional Stability in Wet Conditions

Some ski base manufacturers consider dimensional stability to be one of the decisive material properties, particularly for bases intended for warm and wet snow conditions.

In colder conditions, contact occurs predominantly between the ski base and individual ice grains, whose surfaces are covered by a very thin quasi-liquid layer, referred to as the QLL. At the points of actual contact, this layer can act as a highly effective boundary lubricant.

How Ski Base Material Affects Stone Grinding and Structure Quality – Part 1

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SKI GLIDE PHYSICS · RESEARCH SERIES

Ski Base Material and Structure Quality

PART 1 OF 2

 Effect of Ski Base Material on Structure Quality

Ski base material affects the quality of a stone-ground structure primarily in two ways:

1.     through the formation of unwanted fibres and hairs during grinding,

2.     through the dimensional stability of the material during machining and subsequent loading.

A conventional racing ski base consists of an ultra-high-molecular-weight polyethylene (UHMWPE) matrix reinforced and modified with functional particles, most commonly carbon black, lamellar graphite and/or graphene.

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SKI BASE STRUCTURE · RESEARCH SERIES

Ground vs. Functional Structure

PART 2 OF 2

Stone-Ground vs. Functional Ski Base Structure – Part 2: Can Brushes Really Clean the Grooves?

Dimensional Relationship Between the Groove and the Brush

The difference between the stone-ground structure and the functional surface profile becomes particularly interesting when we examine the geometric and mechanical relationship between structure grooves and brush fibres.

Consider an idealised, symmetrical V-shaped groove with an opening width of approximately 500 micrometres and a depth of only 50 micrometres.

Now consider the brushes commonly used during ski base preparation.

A fine steel brush may have fibres with a nominal diameter of approximately 120 micrometres, while brass brushes used for cleaning or reopening the structure may have thicker fibres, approximately 140 micrometres in diameter.

The Structure That Does Not Actually Exist – Stone-Ground vs. Functional Ski Base Structure, Part 1

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SKI BASE STRUCTURE · RESEARCH SERIES

Ground vs. Functional Structure

PART 1 OF 2

The Structure That Does Not Actually Exist

Stone-Ground vs. Functional Ski Base Structure – Part 1

A great deal has been written about ski base structures—perhaps so much that it has become increasingly difficult to distinguish their essential properties from the assumptions surrounding them.

Let us therefore approach the subject from a different perspective.

On a properly prepared ski, the structure created by the grinding machine does not necessarily remain identical to the effective surface geometry that ultimately interacts with snow.

The original structure certainly exists as a physical geometry in UHMWPE. What does not necessarily exist is a single, permanent and unchanging functional profile determined solely by the grinding machine.

What We Mean by Structure

By structure, we mean a system of grooves of different shapes, pitches and depths ground into the surface of the ski base.

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SKI PREPARATION · RESEARCH SERIES

Hand or Rotary Brush?

PART I OF II

Hand or Rotary Brush? Part I – How Hand Steel Brushes Remove Ski Wax

Hand brushing and rotary brushing are two widely used methods of removing excess wax from cross-country ski bases. Although both methods serve a similar purpose, their mechanical modes of action are not identical.

To understand the differences between them, we must first examine where wax remains after hot waxing, how it interacts with UHMWPE and how the fibres of a hand-held steel brush act on the prepared surface.