Ski tuning is a little like going on a diet or getting more exercise. A lot of skiers know they should do it but somehow don't get around to it. I'm hoping that this simple explanation will do the trick, push you over the brink, and encourage you to get your skis tuned, then keep them in perfect, or near perfect, shape. Why bother? For the simplest of reasons. You'll ski better, much better, on well-tuned skis. Often, when I noticed that one of my ski-school students wore about the same size boot as I did, I would suggest that we trade skis for a run or two, just out of curiosity. Half the time I could barely make a turn on these skis which, at Vail, were often very expensive models, the latest Rossignols, K2s, and other top-of-the-line skis that I knew should ski wonderfully. The problem was always tuning, or rather lack of it.
Here's what happens to skis that makes tuning vital. Early in the season, alas, there are always rocks showing somewhere, poking through the snow cover like mines ready to grab your skis and gouge them. A few scratches and gouges aren't that bad, but often you'll get a scratch right alongside the edge of your ski. This makes that edge dig deeper into the snow. So the ski, at least when turning in one direction, tends to "rail in" and virtually refuses to turn. A lot of skiers simply adjust to this frustrating situation, hopping their skis a little, or generally "horsing" their skis around with a lot of extra body English. Those same early-season rocks can also bash the metal edges of your skis, creating big jagged burrs that catch in the snow and interfere with the smooth sliding and gliding of your skis. A burr on the inside edge of either ski can be enough to block or break the smooth sliding action of the ski in a turn.
And then there's the damage done by just plain skiing, continuous skiing, weekend after weekend, all season long. What happens is that the base of your skis wears down more in the center than it does near the edges. This happens all season long, but especially in granular spring snow conditions. The base then becomes concave or hollow. A ski in this condition is sometimes called a "railed" ski. This too causes the edges to grip excessively, hanging up the turn. What can you do?
The early-season state of your skis' bases is easy to monitor. Just run your fingers along the edges of your skis every time you take them off. They should be silky smooth to the touch. If you feel any jagged burrs, the remedy is dead simple. Just whip a small sharpening stone out of the pocket of your ski suit and rub it over the damaged edge (first parallel to the base, then parallel to the side of the ski). I'm not kidding. I always carry one of those little $2.50 Carborundum stones in my pocket until the snow gets deep and the rocks disappear in January or February. (By the way, an ordinary file won't take these burrs off your ski edge. The burr is "case hardened" from the heat of its contact with the rock, followed by the quenching effect of the cold snow. Only a sharpening stone can smooth out the torn edge.)
Long-term wearing down of the skis' bases (or the presence of a scratch or groove right next to an edge) demands more draconian measures. Take your skis in to the best tuning shop you can find (ask an instructor for a recommendation) and have them redo the bases completely. That means grinding the bases off smooth and flat with a high-tech base grinder (most likely made in Switzerland), and then touching up the job with a hand file to make sure the machine hasn't introduced any small burrs of its own. Unlike waxing, you only need to have your skis tuned a couple of times a season, not every week.
Is it worth it? You bet! A good ski tune-up by a real pro is probably the best bargain in skiing. I love to tune my skis by hand, and after years of practice I'm pretty good at it. But I can't do as good a job as one of the Montana base grinding machines that are now standard at most well-equipped shops. These machines can also put a so-called bevel on your ski edges. What's that? Beveling means that instead of the base being perfectly flat, it is filed to be a tiny bit convex--the opposite of the hollow or railed bases that you need to correct. The theory is that a slight bevel (1 degree or 1.5 degrees) is enough to make the skis initiate or start turns more easily. And it works on most, if not all, skis. If beveling your skis is an option, ask the shop for a 1-degree bevel. Don't overdo it.
Of course, the shop will also wax your skis after tuning them. And you will feel like a new skier.