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Tech Tip # 18:
DINGS, CUTS and SCRATCHES – FIXABLE?
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December 12, 2002 |
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This all depends on where and how deep. Sometimes the ding is mostly just a press mark (like a rill), and will come out with repeated waxing. Always wax the skis several times before trying to repair a mark or ding, as it may come out. Start with several coats of a soft wax, such as STAR Uniblock yellow. Go ahead and put on a harder wax or the wax of the day. Use the skis. Wax ‘em again. See if it makes any difference. If not, the added wax in the base will help if the skis need to be steel scraped. It can’t hurt.
Should the skis be stoneground? Probably not. Take a look at the thickness of the base, or should I say thinness. Look carefully, as often half of what looks like base material is really an underlying carbon fiber layer. Modern race skis are now 0.4 to .6 mm thick – that’s about 1/50th of an inch. Almost nothing. The base needs to be at least 0.3 mm thick to hold wax. So how deep is the scratch? If more than a tenth or two of a millimeter, all stonegrinding is going to do is waste the remainder of the base. Live with the scratch.
Should the bases be steel scraped? Maybe. A very light peel – really just a shaving – will remove any raised edges around the scratch. The cut, or indent, itself will remain, but there will be no protruding base material to cause drag. Steel scraping is best left to a good cross country ski shop, but working on an old pair of skis is a good way to learn how to do this.
Can a cut be filled with “P-tex”? Yes and no. They do this on alpine skis, but they also don’t wax those skis either. Modern XC ski bases are made from sintered polyethylene plastic, a process that allows for pores in the base. That’s where the wax goes. Cheap skis – including many alpine bases – are usually made from extruded plastic that does not have pores and does not hold wax. Melting in base material (“P-tex” is a trade name for ski base polyethylene) will close the pores in the repair area, including the area around the initial cut. It doesn’t matter if the base material is added with a P-tex candle or base-welding gun. The net effect is that this area of the base will never hold wax again. Therefore, the only time the base should be repaired by melting in new base material is when the gash itself is so deep and ugly that the loss of wax holding ability is outweighed by the increased drag caused by the open cut.
What about edge cuts? The problem here is that base material can only be welded to base material, not the underlying carbon or glass fibers. There are no glues that work either, other than the heat-catalyzed epoxies used in the manufacturing process. Small cuts should be sliced and smoothed off, larger open cuts should be welded together when possible.
Skis are a tool and will eventually wear out. Have fun skiing on them. Keep them in good repair and well waxed to maximize enjoyment. Eventually they will need to be replaced. Newer model skis do ski better than older models, especially after 3-5 years (about the span of technological improvements). But keep older skis for poor snow conditions, saving new skis for when there is good snow.
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