søndag 24. januar 2016

Kizmun - Truely Waxless Skis? Glider Wax Mafia vs Science

The trail seems to go cold on the internet forums when we try to follow the mysterious case of the blade and the death of glide wax......

By the early 2000s the majority of XC ski bases were being made in the incredibly tough version of humble polyethylene *aka polythene* . Yes no fancier chemistry than one of the simplest polymers ever made by man. Shopping bags and many different bottles are made of it. It is known for being cheap, soft and easy to melt and recycle. However if you can manufacture very long polymer chains then you come up with a very different beast which is very tough and resistent to wear, while still retaining flexibility and a maleability in the final extruded, or sinter/cast product. Ultra High Molecular Weight Polyethylene was born and finds use in many sports from yarns in paragliding and sailing, to of course ski bases under the most known brand P/Tex 2000, 4000 etc.... UHMWPE

Percieved wisdom in ski circles harks back to the earrly days of plastic based skis which used less dense PE and other plastics. These were " porous" in that the gaps between molecular fibres in the 'nanostructure' and over all micro structure. These are not like biological pores in skins nor definable porousity other membranes like PTFE (Goretex for example) . High density polyethylene is the grand mother of UHMWPE and is still used in applications such as bottles for samples of crude oil and other hydrocarbons, solvents and chemicals. Here even this older, less dense product is prized for lack of adsorption and its inert chemical nature.

Pro ski prep' teams understand that structure in the ski, that is visible patterning by stone grinding and rilling traditionally, is vital to good glide in both XC and Down Hill skis. Note stone grinding! This is a standard ex works delivered ski for what ever purpose, is that it has an abrasive, random structuring often followed by a medium all purpose Vee shaped rilling.  The virgin ski out of the mould is rather nice and shiny when made of UHMWPE and lacks any visible microstructure.

Already the traditional waxers discovered that part of their percieved wisdom from the older 'porous' days, was that saturation with a soft warm weather underwax became useless. Now we can come to a bit of scientific nuance or tautology to some. Wax on UHMWPE is not ABsorbed it is ADsorbed. The subtle difference is that rather than being sucked into the deeper structure of the matieral like a sponge *absorption* wax now largely coating the surface micro and nano structures. Scraping and brushing is really quite aggressive in glide waxing and removes a huge percentage of the wax from the micro surfaces, and because wax is scraped hard it also drags out a lot of the nano adsorbed wax too.

Well waxed cold skis in particular have miminal amounts of wax again. Mild weather waxes applied at a more proffessional level,  are found in a greater qauntity on the ski after prep is finished, this being a function of the coarser, water guiding structure and hence large surface area and more complex I would say that the wax is actually helping compensate for a rough microstructure which otherwise holds water.

Enter the cheeky swede, Kuzmin. He realised while working with un-ground skis made in the new P-texes UHMWPE, that the surface is unbeliebly smooth and that stone grinding in particular introduces a random, overtly rough micro structure which replaces the older 'porous' wax adsorption. Also he used a bit of common scientific sense. He took sharp edge blade tools and scraped off the stone ground mess and then introduced variable cutting edges to introduce a directional microstructure. He also produces a cold or hot rilling tool to introduce rilling pattern, but all this is glider wax.

Here are the myths of glider ski wax enthusiasts

1) Ski bases are porous

2) Stone Grinding is essential for a good start point

3) Ski bases oxidise with use

4) Unwaxed skis  absorb dirt, water, hydrocarbons over time

5) Skis need wax to either break hard crystals in cold / abrasive or exclude water in milder and wet conditions

We have looked at one and two. Three is a nonsense. The whitening of ski bases with use is due to small hairs - it looks white and some pseudo scientist called this oxidation. Under even a magnifying glass you can see the white areas are hairs and excess wax. The self same 'expert preppers' are then introducing the same principle to Zero ski and texture only kick zone where they roughen it up to produce hairs which act as a wax free zone for adhesion.

Moving on, well yes a stone ground ski base is a random uneven surface with no initial direction to the roughness. At a small level, espeically with remnants of old, softer wax, the stone grrinding with or without rilling will hold some crap ADsorbed into the valleys and pot holes introduced by the excessive texturing.

Finally the biggee- that wax does a job which the UHMWPE cannot do. This is just not true, UHMWPE is highly hydrophobic and without stone grinding it is so smooth as not to absorb anything in particular. It is harder than any wax used for cold weather. It has a lower coefficient of friction against hard snow than any waxing when not stone ground and hard rilled. It may however in milder weather, in a flat untreated form, created more suction than a rilled and waxed ski.

There are some circumstances when I would dare say that a flourinated wax prepp on a traditionally texture ski will have a better water dissipating effect and lower coefficient of friction than a Kuzmin prepped waxless ski. However n that uniquely Scottish way, the jury would have to deliver a 'not proven' verdict for either a prosecution against the waxers or the new fangled scrapers. Indeed would any judge let it come to court based on the current evidence?

Kuzmin and some others have percievered in the commercial world now far more than the academic research world, and indeed a German company  (https://melt-ski.com/nivylen) is offering a waxless down hill base system which uses a copolymer = the plastic equivalent of a metal alloy, with enhanced coefficient of friction throughout conditions and a high resistence to wear and its associated "whitening"

However lets get back to basics here and some home truths. In the longer XC ski competiions of 30 and 50 km classic, the skiers get to change skis during the race and this relates to both kick and glide waxing simplky wearing off in what is otherwise a pretty puny distance for the keen weekend ski tourist going cabin to cabin. In the same way that the 'furry' insert of Atomic took its time to gain traction and it took a larger voice from other manufacturers to make it a market sector from a crank niche, the same may be true for 'sharp scraping' and having skis delivered without any grinding. Now our local shop has about a third of their XC classic stock Skintec in two or three guises, and they command about 50% higher price than the usual skis they sell. The skis are most often in fact to be seen on pensioners feet!  Despite being quite sporty, a training or distance race ski, the group who just dont care about the wax shed are buying in their droves to get out and ski.

I look forward to getting a pair of skin based skis and running them Kizmun as true waxless !!! 

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