Clear Base Skis

A few of the clear-base skis we have in the shop
A few of the clear-base skis we have in the shop

For 2013-14 several ski companies will be releasing clear-base skis to the market. Fischer, Madshus, and Rossignol all have clear-base skate skis coming that target wet snow conditions, and Madshus and Rossi are also offering clear-base classic klister skis. These base materials have been in use at a World Cup level with increasing frequency in the past couple of seasons. We have quite a lot of experience with the Fischer and Madshus base formulations, and we’ve spoken with Paul Clark from Rossignol about his extensive testing, last season, of the Rossi clear base. If you’ve spent some time and money developing a fleet of skis, especially if you’ve already included some good wet skis, you might well be wondering whether you now need some clear base skis!

Fourcade sn12-tr-rh-bimms-cp-01-0213The clear bases are generally being marketed for wet snow conditions, but we don’t necessarily recommend jumping right on the band-wagon with a clear-base ski as your first and only pair of wet-snow skis. While the clear bases offer a “clear” advantage at their best, they can be a liability, even in wet snow. Our experience indicates that the clear bases coming to market are at their best in a range of temperatures, but generally in rounded and dull snow crystals. This can include slush, but it can also include granular sugary snow, and even manmade snow in colder conditions. We’ve tested clear base skis in wet new snow with really bad results – there are definitely wet conditions where you would not want to race on them.

Background & History

This is hardly the first time clear bases have been used on skis. Until the late ‘80s clear base skis were the norm. When black bases were first introduced they were marketed as having “anti-static” properties. The whole concept of static electrical charge in ski bases is one that tends to prompt a lot of discussion and disagreement. Does static charge build-up under skis? Does it slow the skis down? Do black bases limit the build-up of static? Do anti-static graphite waxes limit the build-up of static? I don’t have definitive answers to any of these questions. I know that I’ve seen static discharge – small sparks – under skis when classic skiing in the dark. So I’m pretty sure something is going on. I’m also pretty sure that the various black bases that have become prevalent have a very broad range of very good performance characteristics.

Scanning Electron Microscope image of PTex base material, courtesy of Eric Packer. Crystalline sinters with characteristic grain can be seen top right and bottom left. In between is amorphous material with carbon nano-spheres in suspension.
Scanning Electron Microscope image of PTex base material, courtesy of Eric Packer. Crystalline sinters with characteristic grain can be seen top right and bottom left. In between is amorphous material with carbon nano-spheres in suspension.

Black bases are made black with the addition of carbon-blacking in the amorphous material – the lower density material that surrounds the crystalline sinters of ultra-high molecular weight polyethylene in the base material. Various different base formulations might have different additives (which live in the amorphous material) in different percentages, or even different crystalline material. Clear bases are fundamentally the same as black bases – sintered particles of crystalline UHMWPE – but without the carbon-blacking additive in the amorphous boundary regions between the sinters.

There is a prevalent misconception floating around the ski world that all base materials come from one or two factories, and are basically the same. Interestingly, a very similar misconception used to follow pure-fluoro powders around. “They’re 100% fluoro, and they all come from the same place, so they’re the same,” is something we all heard (and maybe even repeated) plenty of times in the ‘90s. Well, I think the misunderstanding about fluoro waxes has been cleared-up, and it’s time to do the same regarding base materials. There are different densities of parent material (UHMPE) used in bases. But beyond that there are lots of proprietary base material formulas with very different working characteristics. While I don’t know the specifics, I imagine that different formulas might involve different additives (materials and amounts) and different sintered particle configurations. There are a couple of major plastics companies that produce base materials for various ski companies (principally IMS Kunststoffe, which holds the “P-Tex” tradename). But there are smaller suppliers as well.

It’s also worth noting that the ski industry is a very small part of the sintered UHMWPE market, to the point where the Wikipedia entry on UHMWPE doesn’t even mention ski bases as an application for the material. The really advanced work is being done in the biomedical world. Eric Packer is a recent Dartmouth grad with an engineering degree and he has described advanced UHMWPE sintering techniques that utilize further descriptors like “nano” and “fluoro”. He seems to think that some of the materials he has handled in the lab might have interesting properties on skis. Ask him about it sometime.

Sophie Caldwell on her way to 16th in the Quebec City World Cup Sprint. Look closely...
Sophie Caldwell on her way to 16th in the Quebec City World Cup Sprint. Look closely…

Ski companies are always testing new base materials – lots of new base materials. Many industry watchers have been prepared for a real revolution in base material – I first heard rumblings of a pending explosion of new technology back in the mid-90s. Meanwhile, Fischer’s plus base (designated “28”) has been their most common and successful base material for at least twenty years. This isn’t because they haven’t tried new base materials – it’s because their 28 base is amazingly good. There are lots of different base formulations in use, and many more being tested all the time.

At various times since black bases became prevalent ski companies have produced clear-base skis for use in racing. Sometimes they’ve been intended for cold conditions, and other times (more often and more recently) they’ve been for wet conditions. The current upwelling of clear base models is representative of a growing prevalence of understanding based on a lot of testing and race experience. The racing world has begun to achieve a critical mass in the recognition of the value of these different base formulations.

One might well ask “what took so long”? I mean, clear bases have been around for ages – if they’re so good, why haven’t they caught -on long before? There are a few reasons worth considering (numbered for clarity).

#1 – Of all the factors governing ski performance on a given day, base material composition plays a relatively minor role. If we add base material to the list of factors bandied-about by conventional wisdom, it ranks a clear last, after ski flex characteristics, grind, and wax. Given the inherent difficulty with limiting variables, the only folks capable of isolating and testing base materials in a meaningful way are the ski companies themselves. Which leads us to reason #2.

#2 – Remember what I said above? Ski companies are testing new materials constantly, and there are lots of formulations for base material in-play. It’s worth noting that “clear base material” as a category is just about as precise and descriptive as “red wax”. There’s no reason to think that the clear base material being tested and used today is the same as the material that was common in the ‘80s.

#3 – Pay attention, because this one is pointed directly at you! The successful introduction of any new materials depends on the successful use of those materials. If you were to test the new clear-base skis in conditions where they didn’t work well, you might not be quick to adopt them. Several years ago Fischer produced a series of clear-base skis for use by World Cup athletes. On the Cross Country World Cup the skis got handed out as soon as they were available, and the waxers and technicians started testing them. They weren’t fast, and over several weeks they started getting returned to Fischer. On the Biathlon World Cup the Fischer guys held onto the skis and tested themselves. Sure enough, they were pretty slow. But then conditions changed, and the skis started testing really well. The first time they handed out clear-base skis, they were a huge success and got raced by a lot of athletes. Guess where the clear-base skis got widely adopted first?

PetukhovClearbaseSo – how does it play out? Who’s using these skis? Noah Hoffman and Kris Freeman have both had clear base skis in their line-up without giving them many race starts. In Kris’s case, the clear-base skis that he has had were a bit too soft for him to feel comfortable on, and other skis always beat them out. Noah has a couple of pairs, and one has been consistently better than the other, but he still hasn’t seen many conditions where they’ve been the best in his fleet. Sophie Caldwell borrowed a pair of our clear-base Fischers last season, and she used them to very good effect in a couple of races in the early season. She won the Supertour skate sprint event in Bozeman on them, and she used them again in the Quebec City World Cup where she finished 16th. Bozeman was very wet, and Quebec was quite sugary and soft.

In general the clear-base skis have been adopted more prevalently in biathlon than in cross country. The biathlon World Cup is run at different venues, generally featuring short loops and a lot of manmade snow in central Europe. It’s possible that biathlon sees more appropriate snow for clear-base skis. But it’s also possible that they generally have more skate skis in their traveling race fleets (because they don’t have to worry about classic), and they have a somewhat more advanced and refined approach to testing variables such as base material composition in skating (because they don’t have to worry about classic).

At this point clear-base skis remain a rare-enough thing that it is hard to determine whether there are days when they’re a must-have. With zero skis, for example, it has become quite clear that there are days where you’re either in the race on zeros, or out of the race on wax. But that wasn’t clear until enough people had zeros to really demonstrate their superiority. There are days when the clear-base skis feel much better than black bases, but it’s best to think of them like zeros. They work when they work, but they’re not the first thing you should reach for. Perhaps, at some point, it will become obvious to everybody that clear-bases are “required” in some conditions. Until then, they might be a quiet advantage for those who have them and learn how to use them. Or they might fizzle and fade from use. But my guess is that they have a place, and will slowly gain traction, in much the way zeros have.