Does the base of a ski oxidize after sliding on snow?
This question was put in front of me on the ski trail Sunday, and I've been thinking on it and doing a little investigating.
Ski bases appear to be made of polyethylene (polyethene, I suppose IUPAC would call it). There are no functional groups at all, just long, long chains of hydrocarbon. Polyethylene is completely saturated with hydrogen. It's nearly unoxidizable, unless you actually set it on fire.
A protective coating of wax on the base reduces the chance of air oxidation even further.
So I have to agree with some forum (I apologize for not having the url here) somewhere: when bases begin to show white (or grey on my black bases) it may be called oxidation in the ski lodge, but that isn't really the issue. Instead, the snow has physically damaged the base by putting lots of tiny little shreds into it, roughing the surface. It is of course real damage to the surface of the ski that will reduce glide, and it is to be avoided. You're overdue for a new coat of wax.
How rapidly this problem develops is going to be largely due to snow conditions when you're on the skis. Watch for it especially after fresh snow, when the snow crystals are still sharp, or when the snow is cold and icy.
2 comments:
Thanks for your post. It supports what I have thought. I did find the following and, if you have time and interest, I wonder about your interpretation. Thanks
Oxidation process and its effects
Oxidation starts once polyethylene base makes contact with oxygen and solar irradiation. It speeds up with the rise of the temperature and continues during storage. These two factors lead to the production of oxygen containing free radicals and capable to pull out hydrogen atoms from hydrocarbon structure of polyethylene. This is a chain reaction and it lasts all the time while the base is in contact with oxygen, thus, leading to the formation of decomposition products, such as ester, acids and acetone. This structural change strongly deteriorates physicochemical characteristics of polyethylene (its tensile strength and modulus, density, flexibility and coefficient of friction). At the same time, it reduces crystallinity a lot and forms white micro-cracks on the surface. This reaction is irreversible, leading to the creation of “sterile” zones. Oxidation can be limited and slowed down in two ways: By adding anti-oxidants aimed at preventing radicals’ activity during the process of base fabrication. By applying an air and UV proof film to protect ski base, which is WAXING! Thus, the role of waxes consists in protecting the surface of your ski base against air oxygen and in preventing the above oxidation process. Waxes preserve mechanical properties of your ski base, that’s why you should always wax your skis after skiing, be it a training session or a competition.
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I'd be interested in seeing the data that the NAPPA-DRAGONSKI folks use to back up their claims. Another thing that would be fun would be doing the experiment. If the oxidation occurs from exposure to oxygen in air, then given a year of unwaxed time I'd think that there should be noticeable oxidation on a ski base.
I've got some old skate skis around the house, I think, and I'm inclined to start the experiment. I'll wax a patch and see what happens over time. We should chat again in a year.....eh? :)
Thanks for reading the blog!
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