How Ski Wax Works (Really)

[Manney]

Aim. To explain the basis behind modern glide and grip wax… to help fill an identified gap in the Telemark Talk knowledge base.

Method. A slow build article, broken down into several parts. Interspersed with illustrative posts from the forum. With background reading at the end.

Assumptions and Limitations. The underlying assumption for this piece is that skiers want to wax for some kind of performance… not necessarily racing but better and more consistent characteristics when skiing uphill, downhill or on the flats at moderate or higher speeds. If this doesn’t apply to you, no need to read any further.

Not a science or chemistry lesson… more of a skier’s application of stuff that scientists and chemists work out on our behalf. Not a sales pitch for any particular brands of wax or fancy treatments. Buy what you want, use what you want, apply it however you want but do try to understand what you’re getting for your time and money… and what you may be missing out on if you ignore the principles behind certain waxes.

This isn’t going to be an article on how to wax. Lots available online and it’s a subject that is best covered in a video. It’s more going to be about “what” and “why” behind glide and grip wax.

Health Warning. People who get triggered by thinking about stuff they’ve ignored for years may find the subject matter disturbing. Any and all comments made by the author are not directed AT you. They are freely provided FOR you. Think of it like a gift… a lovely Finnish Puukko knife that you can use for carving or fieldcraft… but is not necessarily an invitation for you to fall on it, cut off a finger, or commit ritual suicide. Or complain about any of this afterwards.

Nothing here is my Idea. We stand on the shoulders of the giants who came before us. Lots of info on this subject, dating back to the 1940s, is available. The best stuff started to be published from the 1970s onward. Not because people got smarter. But because the means of measuring, recording, and analyzing data rapidly advanced once the price of computing came down. So in many ways, what is provided here is a literature review of sorts… an abridged version of a few hundred pages of text published by academics, businesses, technicians, and sensible skiers.

[Manney]

What Does Ski Wax Do? Ski wax manages resistance. The key word is “manage” because wax does a lot more than reducing resistance (glide wax) or increasing resistance (kick or grip wax).

Resistance? Don’t you mean “friction”? Nope. Friction is only one of the things that resists a ski. There is also suction and static, which can be significant inhibitors in the movement of a ski. So resistance is a better, more encompassing, term.

But first, let’s focus on friction…

Friction exists between two or more moving surfaces which are in contact with each other. It is divided into static friction and dynamic friction. Static friction exists between surfaces that aren’t moving relative to one another. Dynamic friction exists between surfaces with differences in relative motion.

A crampon provides a good example of static friction. By virtue of its design, it firmly engages snow or ice. The higher the pressure, the firmer the engagement with the snow or ice. When pressure is reduced, the crampon disengages, the snow or ice fall away from its talons, and the climber can lift that foot and move it forward with very little resistance.

An aircraft ski provides a good example of dynamic friction. Landing on snow generates a lot of friction because speeds are quite high. So much friction occurs that the snow immediately under the ski can turn to water and boil until speed is reduced. This all happens very quickly and in localized areas of the ski, so it largely goes unnoticed.

Eventually, speed is reduced to the point where the aircraft comes to a stop. There is no longer any dynamic friction but the static friction between the aircraft ski and the snow (assisted by the weight of the plane and the roughness of the surfaces on a microscopic level) stops the plane from moving even if it is parked on a moderate incline.

Nothing is done to manage friction resistance of crampons or aircraft skis. Removing burrs, polishing or even honing edges make them better at what they’re designed to do, which is grip or slide. But not both. Leg muscles or aero engines “overcome” the effects of friction resistance. There’s no internal regulation within the components themselves to “manage” it in any dynamic way.

Suction and static resist movement too. Suction occurs when two surfaces, separated by a trapped layer of fluid, move relative to one another. The thinner the layer of fluid and higher the speed, the higher the suction. We see this in shallow water boating. Even if the depth of water is deep enough to keep the props off the bottom, they will still touch if speed is increased and the water being displaced by the hull has a place to go. We manage this by adjusting trim, but the suction is still there. It’s not a huge factor but it’s still something that benefits from a bit of management.

Static is an easy one. We’ve all watched a thin piece of wool or silk stick to a plastic rod when it is rubbed. The faster the rod is rubbed against the material, the better the “stick”. But this only happens in dry conditions and speed is a factor. Fortunately, the resistance of static isn’t all that high. But it is still something that the right wax can manage.

So to summarize, resistance comes in four forms:

1. static friction
2. dynamic friction
3. suction
4. static

The first two are major. The last two are relatively minor. All need to be managed to optimize performance, regardless of whether the skiing is recreational or competitive.

So let’s turn our attention to snow.

[Manney]

Started out looking for the hundreds of words used by people in the high north to describe snow. LOL. That’s appears to be an urban legend, so going to focus instead on temperature and age.

We know snow is frozen water that starts out in a crystalline form. It reaches this state as moisture freezes as it falls through the atmosphere. If the atmosphere is uniformly very cold and dry, the crystals that form are large, have complex shapes, and are hard. They end up looking something like this:

If they form while passing pass through a layer of warmer and moister air, the melting process results in smaller, rounded, and softer crystals. They might end up looking something like this:

None of this does justice to the complex structure of snowflakes. It simply illustrates that there is a difference, at the crystalline level, between snow that forms in very cold temperatures and snow that forms in fairly warm temperatures.

Characteristics of Snowflakes, Ukichiro Nakaya, Pioneer in Snow Research

That difference is recognized on the packaging of some ski waxes. Look at the bottom of this stick of Swix Green. Notice the diagrams at the bottom? The one on the left (spiky snowflake) is for new snow. The one on the right (rounded snowflake) is for old snow.

Artificial snow is a whole different matter. Created by spraying water droplets into the air, the resulting “snow” falls as irregular balls of ice. This is why it skis differently than natural snow found in the backcountry.

Large, complex, and hard natural snow crystals need time to settle and lock together after falling on a cold surface. Smaller, rounded, and softer crystals settle quickly after falling on a warmer surface. A good analogy is a bag of rough gravel versus a bag of smooth ball bearings. The gravel takes a long time to consolidate because the sharp corners don’t slide very well against each other. The ball bearings consolidate almost instantly.

Movement rounds off hard crystalline snow crystals. Moisture, in the form of microscopic water droplets, accelerates the process and kick starts consolidation. Time, gravity, sunlight and even wind can contribute to this process, resulting in “old snow” as early as three days after snowfall.

Old snow is less abrasive than new snow, even if temperatures drop during the consolidation process. This is because the shape of the ice crystals change, rounding off enough to be able to slide over and under with very little resistance. Increasing temperature or sunlight can give rise to free water forms, which then acts as a lubricant. So even if the snow packs down and feels grippy, it is actually quite slippery at a microscopic level.

None of this is a new idea. It has been said before, including by people on the forum who take the time to think and observe about what’s happening around them. (Well said, @beeeweee)

This is a good point to start talking about skis and wax.

[Manney]

Ski bases are made from polyethylene. This type of plastic was developed in the 1950s and saw immediate use in a wide range of consumer items, from plastic milk jugs to sealed food bags.

Its remarkable attributes of impact strength, water repellency, and resistance to wear led to its use for the bases of skis and even artificial joint bushings. In higher density formulations, polyethylene is used for ski bases. The trade name of this material is P-Tex.

P-Tex ski bases are manufactured in one of two ways. The cheapest ski bases are extruded. Polyethylene pellets go into a large hopper, are melted, pressed between high pressure rollers, and exit the machine in sheet or strip form.

Higher quality P-Tex ski bases are made by a process called sintering. Polyethylene powder is fed into a very powerful press. Extreme pressure fuses the powder into billets. These billets are not solid, but retain porosity. The porous billets are then lathe cut into strips suitable for use as ski bases.

This is how the sintering process works in theory:

This is how sintered material ends up looking under a microscope:

Regardless of whether it is extruded or sintered, P-Tex has certain attributes and limitations. On the plus side, it is highly water repellent or hydrophobic. High density formulations are impact resistant… P-Tex will spring back from hard knocks. It resists a wide variety of chemicals.

But there is no such thing as a perfect material. P-Tex’s limitations include a limited ability to handle heat and low hardness… it can be easily scratched by many other materials including ice at temperatures just below freezing. (See polythene, which is an alternate spelling for polyethylene)

Here’s where we start looking at the nuances of ski base construction and the role of wax…

Left unwaxed, a ski with extruded base has less friction over snow than a ski with a sintered base. SAY WOT? Yes, it’s true, which is why snowboard makers in particular offer both types of bases. People who have no intention of waxing, ever, are better off with a ski or snowboard that has an extruded base. This is because of something called “wetting”.

A wetted surface slides across snow easier. An extruded ski is not porous… and polyethylene is hydrophobic. So whatever water is under the ski acts as a lubricant between the base and the snow.

A sintered base is porous. The P-Tex might by hydrophobic, but the small voids left over from the sintering process aren’t. Water gets into these void spaces and sticks to the water under the ski… or the voids act like little suction cups and slow the ski down… or dirt, the most evil of things for a ski base, gets into the voids and catches across the snow.

So why pay all the extra money for skis with a sintered P-Tex base? Because they’re faster… much faster in fact… when properly waxed. Whatever wax is put on an extruded base doesn’t stay there very long… they’re nothing to hold it and P-Tex is notoriously slippery.

Yeah but… that doesn’t explain why a properly waxed sintered base is faster than an unwaxed extruded base! Especially if polyethylene is so slippery in the first place. These are good points but only if you ignore the effect of CONTROLLED FRICTION, which is the principle upon which ski wax works.

Controlled friction is an important principle. Too much water under a ski will slow it down. So will too little. The trick is developing a treatment (like glide wax) that imparts just enough friction to help create a thin layer of water under the ski in a given temperature range. But that’s not all… an effective glide wax also needs to do the following:

1. Repel water
2. Avoid icing
3. Soft enough to get into the small pores of the sintered base
4. Hard and strong enough to resist scoring, shearing and tear-out

At the moment, there’s no single glide wax capable of doing all these things. Here’s why:

Remember how ice hardness changes with temperature? (Blue line). Remember how snow is comprised of ice crystals and the colder temperature at which snow forms the sharper those crystals? Remember how the moisture content of snow changes with temperature?

All these things make it impossible at the moment to create ONE glide wax that does everything well. The best the industry can achieve is to formulate a glide wax to deal with the most important issues in a relatively narrow temperature range.

So a cold weather glide wax will focus on hardness and durability as a priority. It only has to deal with whatever traces of water are created by controlled friction, nothing more. Dirt isn’t a priority because cold snow hasn’t melted back and concentrated contaminants in the surface. Cold snow is dry snow, so icing is t a huge issue.

Conversely, a warmer weather glide wax will focus on moisture resistance (rather than generation). It won’t need to focus as much on hardness or durability because snow crystals will round off quickly after falling. Icing is a big issue at transitional temperatures, so anti icing agents will be added to the wax.

If you look back to the graphic, you’ll also see a red line. Paraffin was used in the past as a glide wax. Why? Because its moisture repelling characteristics are very good. But its hardness doesn’t follow the same curve as ice, so it simply wears off at cold temperatures. In doing so, it contributes very little to controlled friction at colder temperatures… so it stops being a good glide wax. This is because it was never formulated for skis. It was “adopted” by early skiers, who would raid the family cannery or steal a candle for enough paraffin to protect their wooden skis against moisture. Whatever glide improvements occurred were temporary, transitory, and secondary.

One of the reasons for this is scuff resistance. Paraffin is softer than ice crystals (aka snow) at all temperatures, so it wears off on the areas of the ski under constant contact (the gliding zones). So do glide waxes or any other kind of wax that are either too soft or not formulated with scuff resistance in mind.

Now let’s look at PTFE, or Teflon. A C8 molecule that was used as an additive for ski waxes until being banned due to carcinogenic effects…

When you look at Teflon, you’re looking at the power, and pitfalls, of modern chemistry. As an additive for ski wax, its performance is phenomenal. It is harder than ice at most temperatures, resists moisture, and actually repels dirt. Yup, you heard that right… dirt runs away from Teflon because of the water tension at its surface. Like paraffin though, Teflon was just an adoptee. It was never developed for the expressed purpose of enhancing ski waxes. It was developed as an effective sealing material for America’s nuclear weapons program… and later as a coating for cookware. LOL.

As marvellous as PTFE was as an additive, it wasn’t even enough to result in a “one wax does it all” glide wax. So even after the FIS ban and all the product liability and environmental concerns, we’re still stuck with selecting waxes that are formulated for narrow temperature ranges and snow conditions. Fortunately, those waxes still work well.

And here’s what they look like after being applied to a sintered base, as seen through a microscope:

Images taken from the Maplus Waxing Manual

You can see that glide wax, by virtue of it being heated-in and scraped, smooths the base and saturates all of the microscopic holes that would otherwise trap water in a sintered ski base. The impact this has on glide is considerable.

Here’s a measurement of the force required to move the same test ski across snow of the same temperature. One is the wrong glide wax for conditions, one is the right wax. The peak forces are those required to overcome the initial static friction (aka stiction). The mean forces are those required to overcome dynamic, or kinetic, friction.

Wrong wax:

The initial high peak indicates static friction. The lower peaks, reducing over time, indicates dynamic friction. The reduction in initially higher dynamic friction indicates that some water is forming. That’s why the friction goes down. Regardless, the friction remains consistently higher than that of the correct wax (below).

Some might think that the dynamic friction of the wrong wax will eventually catch up… but they’re not thinking through the problem. Kick and glide are cyclical. The process repeats… along with the same static and dynamic friction patterns. Each and every time. So the wrong glide wax will have much higher friction than the correct wax throughout the entire ski session.

This is now the point where we can start to examine grip waxes…. But before we get to that, let’s take another look at ski construction.

[Manney]

A BC, XCD, or AT ski has camber. That camber (arch in the middle) corresponds, more or less, to the grip zone of the ski. That grip zone either has scales or it doesn’t. If it doesn’t, it needs a special type of wax (grip wax) to impart a degree of traction to the ski.

Unlike glide wax, a grip wax doesn’t need to deal with scuffing. It needs to grip the snow and release the snow. The feature used to control this process is (1) the camber and (2) the weight of the skier. This is different than the glide zones, which are in constant, weighted, contact with the snow.

Because scuff resistance isn’t a priority but traction is, grip waxes are much softer than glide waxes. They don’t require heat for application. They can’t be brushed out because doing so would hopelessly clog a brass or nylon brush. Until weighting, the surfaces to which they are applied barely touch the snow. When they do, they’re not supposed to slide…

… but they are expected to grip when plunged down and hold the snow until released. The ski is then moved forward with the grip zone clear of the snow’s surface. Whatever motion the grip zone gets on the snow’s surface is mostly up-and-down.

This frees up grip wax manufacturers to focus on different things. They don’t spend time concocting formulations that repel dirt because dirt adds grip. so much. They don’t care about controlled friction… because a water film isn’t needed under the grip zone. They care about water repellency just enough to prevent icing. That’s it.

What grip wax manufacturers focus on, therefore, is formulating a wax best suited to grab-and-release. This a much different problem than glide wax formulation but it’s actually the more difficult of the two to get right. Here’s why…

A grip wax that tenaciously grips an ice crystal won’t release it. More and more particles will be collected on each successive pass. In very cold weather, the spiky shape of the snowflakes will stick to each other. So, warm or cold, the grip zone of the ski will collect snow or ice until the void of the camber fills. The ski will get heavier and eventually even glide will cease.

So the job of the grip wax is to hold onto ice crystals (aka snow) just enough to provide traction but not enough to prevent those same crystals falling fall away when the ski is unweighted. At the microscopic level, the grip between the waxed pocket and the ice crystals needs to be slightly less than the potential grip of snow-on-snow at a given temperature. The process doesn’t need to be perfect because even if the snow crystals don’t fall away from the grip zone on lifting, they will shear away easily with each gliding stroke. Why? Because there’s always some contact between the pocket and the snow surface, even on the glide stroke.

Getting grip wax formulation right is still quite difficult. The chemical engineer has two problems to solve. The grip-release function and something that works equally well on sharp and round snow crystals.

If they get it right, the grip zone only contributes static friction to the ski. If they get it wrong, or the skier uses the wrong grip wax, then both static and dynamic friction become a problem.

This brings us back to the beginning, when the concept of managed resistance was introduced.

[Manney]

But before we get to managed resistance, let’s look at the whole resistance equation.

Kick and glide appears simple enough when grip and glide waxes are viewed in isolation. In reality, the skier has to deal with both of these things at the same time. The diagram above highlights that the real problems exist outside of an ideal ( -3 to -5C -or- 23-27F ) temperature range.

Warmer than this, things like water suction and drag become a problem. Colder than this, the snow is very abrasive because it’s hard to maintain a water film.

Managing resistance is, therefore, about minimizing adverse effects with the right ski wax. Like static and dynamic friction.

Unmanageable problems are introduced when the wrong type of waxes (kick or glide) are used for the wrong thing. Let me explain…

Kick wax is soft. It doesn’t get into the structure of a ski. Rather, it sticks to the surface. It cannot be brushed out. It can be removed by scraping or the use of a solvent. This means that there is no practical way for it to be treated to deal with water when it is applied in the glide zone. It is either “on” or “off” the base.

Glide wax is harder. Proper application gets it into the structure. It can, and indeed, should be brushed out. Why? Because it’s only meant to fill the voids in the sintered P-Tex. Brushing out glide wax puts longitudinal grooves in the glide zones. These grooves are small… barely deeper than the grooves on an old phonographic record. But they allow any excess water that forms under the ski to be channeled away. Because of the nature of the P-Tex structure, the depth of grooves caused by brushing is neither too deep nor too shallow.

This is what a basic rilling job will do to the base. A brass brush will do the same thing but the grooves will be far finer and the base’s ability to manage excess water will be far less.

At the other end of the temperature spectrum, grip wax in the glide zone slows the ski down. It is designed to grip. Even if it is a very cold temperature wax, it still imparts far more grip than glide than a proper glide wax.

So the only thing you get by applying a layer of grip wax over an entire ski is resistance. Hydrodynamic resistance at warm temperatures and more dynamic resistance at low temperatures.

Why Do People Misuse Wax? It’s important to frame the answer to this question beyond simply picking the wrong wax for the day. That’s easy to do when waxing the night before a ski session, the forecast changes, or you like in an area subject to wild temperature fluctuations.

Misuse of wax means that they purposely deviate from the manufacturers recommendations for a specific set of conditions. Like using warm weather glide or grip wax at 40 below… or using a cold weather wax in the lower 48 from early winter to the end of the ski season in the spring.

One answer is that they simply don’t know the difference between a ski that grips well when it should and glides well when it should. We’re not talking about minor variations from the ideal grip or glide, but huge deviations from what an experienced skier would consider acceptable performance.

Another answer is that they don’t ski fast enough to notice the difference… walking on skis on the flats, climbing hills, and descending slowly doesn’t create much dynamic friction. It’s mostly static friction, just like walking. So it feels “right” because it doesn’t require any particular skill, athleticism, or physical work to do above and beyond that normally associated with walking.

Or maybe they are skiing fast enough and noticing that the grip wax you’ve misapplied to the entire length of the ski wears off after five or six miles? This is because grip wax isn’t designed to resist scuffing. Why? Because the manufacturers formulated it for the unique conditions of a wax pocket (cambered grip zone).

An inappropriate grip wax choice for a day at a lift served resort isn’t going to be a big deal. Too much grip? Ride the chair to a steeper run. But this sort of skiing isn’t BC, XCD or AT. It’s resort skiing. And it often results in stiction, which will be explained in a few moments.

Putting glide wax along the entire length of a ski? This is what downhill skiers do because they don’t need grip. It’s a rookie mistake on an XC, XCD, or AT ski… basically anything intended to be used to traverse varied terrain under a skier’s own power… unless you’re relying solely on skins for grip. But that’s another matter beyond the subject of this article.

Sometimes, people use grip wax along the entire length of the ski to get the overall level of grip they want. This can happen after a few failed experiments using the wrong wax in the correct place (the wax pocket) or poor technique (limited weight shift on the flats and uphill sections of the tour). In this case, the skier has got the grip they need for climb but pay for it on the flats. A more effective approach would be to achieve the same level of grip with the right kick wax and still have enough glide to easily ski at a fast pace on the flats and on the descent. This is what you can do on a properly sized ski and using proper technique on a ski with any kind of camber that has been waxed properly.

Does any of this matter or is it an issue of “preference”? Depends on how you look at it. Using the incorrect wax can mask some skier issues (like poor weight shift) while creating new problems (like control).

Another control problem is stiction… that “grip-slide-grip” phenomenon skiers feel when an incorrect wax is used. Hit powder, stick. Hit soft snow, glide. Or vice versa. Turn in and out of a tree line or shaded area, stick, glide, stick. Fall down, get up. Do it all again… unless this ends with a broken bone, blown tendons, or utter frustration.

This sort of thing is that which wax manufacturers hope to save you from… consistently poor, or inconsistently average, performance. Which is why they make wax for very specific snow conditions in the first place… and have enough formulations to give you grip AND glide at temperatures ranging from arctic cold to spring warmth.

[Manney]

More Reading

The Friction of Snow Skis (University of Montana)

https://arc.lib.montana.edu/snow-scienc ... 18-027.pdf

Science of Snow (National Snow and Ice Data Center)

https://nsidc.org/learn/parts-cryospher ... ience-snow

A Guide to Snowflakes (Caltech)

https://www.its.caltech.edu/~atomic/sno ... ss-old.htm

A Scientific Perspective on Reducing Ski-Snow Friction to Improve Performance in Olympic Cross-Country Skiing, the Biathlon and Nordic Combined (Multiple Authors)

https://www.frontiersin.org/articles/10 ... 44883/full

Why Are Skis Waxed? (New to Ski)

https://newtoski.com/why-are-skis-waxed/

Ski and Wax Testing

https://www.skinnyski.com/training/arti ... 171218.pdf

Wear of ski waxes: Effect of temperature, molecule chain length and position on the ski base (Multiple Authors)

https://doi.org/10.1016/j.wear.2017.05.004

The Science of Ski Waxes



Do You Choose Extruded or Sintered Ski/Snowboard Base? (Waxnboard)

https://waxnboard.com/en/kies-je-voor-e ... oard-base/

And something to watch and consider…



There are contrary views out there on ski wax, but none of them come from companies that spend time in the lab, on the snow, and work with athletes to develop the best grip and glide formulations for conditions.

None of them come from athletes winning races.

None of them come from performance recreational skiers who go out in a variety of temperatures and terrain.

Many contrasting views from short distance casual skiers, those who ski shoe, or people who ski only on granular man made snow because none of these truly test the frictional limits of a ski.

[Manney]

Manufacturer Wax Charts (Glide)

Manufacturer Wax Charts (Grip/Kick)

Rode:

[fledersau]

Alot of information there! Thanks! Seems a logical conclusion... Eager to leave my skins at home and commit more to gripwax.

[Manney]

Skiers operating in the “Goldilocks Zone” can get away with a lot. The consequences of choosing a wax one step too high or too low aren’t that serious. Hard waxes are more forgiving.

But outside that narrow range, performance (speed, control, consistency) really takes a hit.

This is why casual skiers, who seek ideal conditions, dismiss the importance of careful grip wax selection.

Wax is cheaper than skins. Faster most* of the time too. Save skins for when they’re really needed and they’ll stay in better shape and last quite a long time.