Introducing the Star Digital Pro 190C Iron
Davide Mosele, the son of the founder of the Star wax company, and the head engineer and product developer, has a degree in electrical engineering. When the guy who designs the wax also designs the iron you use to apply the wax, you’ve got a good idea that he’ll get the important stuff right. The Star digital iron has been my favorite iron and the one I’ve used since it first showed up in 2006. Now Davide has made a new high-temp iron with a 190 degree capacity and a thick base, which is superb for applying fluoro powders. We received the first 110 volt versions of this iron last December, and have been using it ever since. It’s a great tool.
Anybody who waxes for a collegiate or Nor-Am level team is very familiar with fluoro powder application, but there are still huge misgivings about fluoro application among the general public, and we talk to many people who refuse to apply fluoro powders with an iron for fear of destroying their skis. Indeed, with many of the modern high-melt-point powders that are dominating the market these days, the necessary iron temperatures are daunting! But fluoro powder application is neither difficult, nor particularly dangerous to the skis. I’ll try to explain by making a few simple points.
Disclaimer: The following information is the best representation of my understanding of the way base material and wax works, and it’s based on many conversations with people in the industry, and with chemists and engineers outside of the industry. It also supports and fits my personal experience working with a lot of skis, and witnessing the different creative types of damage that can be done to skis. However, I don’t have solid “proof” of any of this, and I’ve been able to find alarming little documentation explaining exactly how wax and ski bases do work together. So take the following with a grain of salt. If I’m totally wrong, it’s not for lack of testing a ton of skis and talking to the best people I can find.
Point #1:
Ski bases are made up of two different materials; crystalline ultra high molecular weight polyethylene (UHMWPE) and lower density amorphous material. The crystalline material is very tough – it has a melt point far beyond what you can apply with any iron, and is very stable, not to mention slippery. Wikipedia may tell you that UHMWPE has a melting point of between 130 and 136 degrees C, but that’s misleading. “Ultra High” is not a specific descriptor of the molecular weight of a polymer, and the melt point is directly related to the molecular weight. The melt point is far, far higher than 136 degrees C – otherwise we would be melting our skis anytime we put on anything harder than a violet paraffin, and that clearly isn’t happening. However, the amorphous material in the base goes through a glass transition at around 130 degrees C, and that process results in a chemical hardening of the base material.
This hardening process is inevitable if you’re ever going to use cold or hard paraffins on your skis, and it’s not a bad thing. But it’s often confused with “burning”. It is a good idea to harden your bases intentionally so that the density changes uniformly and you end up with a stable and even base surface. This hardening step is a standard operation among World Cup technicians when it comes to bringing new or freshly ground skis up to speed.
Point #2:
Bases can be easily damaged by excess heat. But in my experience that has more to do with overheating the wax than overheating the base material. When you iron wax on your ski base, the wax goes into solution in the amorphous material in the base; like sugar dissolving into tea. The amorphous material in your base also carries the additive content of the base in suspension – primarily carbon blacking, and whatever other proprietary additives the base companies put in the material. In order for the wax to go into solution, a couple of things have to happen. First, the base material needs to be warm enough to “open up” and accept the wax. This seems to happen at iron temps between 110C and 120C, depending on the base material formulation. Second, the wax needs to be sufficiently fluid to flow easily. When both of these conditions are met, the wax will dissolve into the base essentially immediately. It’s not a gradual process. The depth of saturation is a matter of the temperature gradient in the base; wax will penetrate as far as the necessary heat penetrates.
So far so good. We heat the wax, the base opens up to allow the wax to dissolve into solution, and the process is fast. But damage occurs when the wax gets overheated. Each wax formulation can carry a certain amount of heat before it’s got so much heat energy stored in it that it causes instability in the amorphous materials of the base. Functionally, this means that the amorphous material is destabilized, and you end up scraping black wax shavings. That black stuff is the carbon-blacking from the amorphous material, and it’s a sign that your base material has lost its integrity due to excess heat in the wax. The specific temperature at which this occurs depends on the wax, and this is why it’s important to use an iron with good temperature control, and to follow the wax manufacturer’s iron temperature specifications.
We see a lot of damaged skis come into the shop for grinding. Many of them are unevenly hardened, and this makes them a pain to work on, but it doesn’t necessarily make them slow. However, bases with destabilized amorphous materials are always slow. They are notorious for not holding wax, and they tend to turn white after a little bit of skiing (most skiers tell us that their bases are “oxidized”, which does not, in fact, seem to be the case). This happens either because of too much heat in the wax, or because of too much time with the iron at a low temp, which causes a condition like overcooked pasta; total loss of base integrity.
OK – so now you have some idea of how bases get damaged, so I should probably explain why a 190 degree iron for applying pure fluoros isn’t a big deal! The reason is simple; pure fluoro powders are a surface treatment – they don’t got into solution in the base. When you iron a fluoro you cause it to melt and flow very rapidly, and it solidifies and recrystallizes just about as rapidly as the heat source moves along. But the fluoro powder doesn’t carry heat into the base the same way that paraffin does. It stays on the surface. Because of the extremely high heat at the surface, it’s important to have a well (and evenly) hardened base prior to fluoro powder application. If you don’t, you’ll do a quick and violent job of hardening the base, and you could damage the base in that way. But if the base has been appropriately hardened prior to fluoro application, then you shouldn’t do excess damage.
Let’s be clear: fluoro powder applications are hard on the base material. If you want to take perfect care of your skis, the best thing to do is to never put fluoro powders on them. For that matter, you probably shouldn’t take the travel wax off them, or take them out of the ski bag either. And while you’re at it, it’s a good idea not to drive your car, since it will keep its value better if you don’t. But for those of you who want optimal performance from your equipment, fluoro powders are part of the game, and you shouldn’t be afraid of them.
The critical elements to have in place are sufficient fluoro powder coverage so that the fluorocarbon can easily flow to cover the entire base, and sufficient heat to allow the fluoro to flow easily. Some wax manufacturers may object, and I’ll hear them out, but I have never seen ill-effect from using a very high iron temperature on any and all fluoro powders. Even powders that will flow at 140 degrees seem to just flow faster and more easily at 190 degrees. You may have heard that World Cup techs like to crank the irons up and move fast. That’s true, and a good idea with fluoro powders, but not true and a bad idea with paraffins (see point #2 above).
Even just five years ago many of the fluoro powders in common circulation were easy to use, with working iron temps around 140 or 150C. But the more modern, and generally better, powders tend to require irons temps of around 180C or more. To be “in the game” and do good, confident, and professional work these days, a good powder iron is a requirement. I was pretty happy with the Star 180 degree iron; it was a big step up from the old 160 degree irons. But the new 190 degree iron makes all powders feel manageable and easy to work with. I just leave mine set at 190 and use it only for powder. It’s a heavy iron, and I prefer to work with the regular 180 iron for paraffin.
Finally, here is Gunnar demonstrating that, with enough confidence (or ignorance of consequences) and the right tools, even a ten year old can apply fluoro powders to World Cup skis. Sorry Noah.