Are climbing skin cutters are as controversial as ski helmets? I kind of hope not but who knows. So, with trembling keyboard and hesitant finger tips I file this report:

Climbing skin cutters for backcountry skiing. From left to right, trad razor blade, BD's old school but still effective trimmer, G3 trimmer was the first to cut without moving skin around, K2's new offering also has built-in offset.
Cutting skins to fit ski sidecut used to be a hassle. It still is unless you get everything right. Trad style was you did a simple sounding process of offsetting the skin to one side on the ski, cutting, then moving to the other side, cutting, and so on. In theory it worked, but moving the skin from one side of ski base to the other tends to get tedious, and the skin can end up uncentered or with a built-in curve once it’s cut. Key to making things easier is leaving the skin stuck to the ski and using a cutter that “automatically” offsets your cut from the ski edge. G3 was the first to come up with such a cutter. Now K2 will sell one as well.
For my test, I acquired a nice fresh pair of Black Diamond 100% mohair furs for my sweet new pair of k2 Coombacks. Not thinking through past experience, I ordered a fairly skinny pair of skins, my mistake but a good way to see the limits of skin trimmers. In their stock width, the skins were slightly narrower than the ski at tip and tail, while overhanging more and more towards the middle. Using the traditional razor method of trimming the skin, I easily got a good cut in this configuration.
But problems arose with the G3 and K2 cutters in that they have trouble starting a cut on the edge of the skin, rather than coming in from the end. In other words, because my skins were already narrow enough at tip and tail, the cut needed to be started on the edge of the skin, away from the ends. Turned out, the only way I could do this with G3 and K2 was to start the cut by first hacking in with a razor blade to make a start notch. Not ideal, as this resulted in a less than smooth curve to my cut.
So first lesson here is when you order skins, get them a centimeter or so wider than your skis AT BOTH TIP AND TAIL so you can start your skin cutter cuts at the end of the skin, and have plenty of off-cut material to work with.

The G3 cutter is intuitive to use, but because the cutting guide slides between skin and ski, it can be difficult to slide accurately due to it sticking to the glue and jerking around. Partial solution to this was to spray water on the skin and cutter just before the cut. The cutter can be cleaned for re-use by soaking in paint thinner or any other solvent that doesn't eat plastic.

Ah, but this is Wildsnow.com and everything shall be modified. To make the G3 cutter slide smoother and less grabby on the skin glue, I cut a crude void in the part that slides between skin and ski, so less surface area grabbed the glue. Combined with water this slid MUCH easier and is perhaps a change G3 might consider in some form.

K2 backcountry skiing skin cutter is less intuitive than the G3 (read the instructions) and pretty much requires the ski to be in a ski vise as it has to be held very steady. But other than a very small offset guide the K2 rides outside the skin and away from the skin glue. Thus, when you get it cutting correctly it is very smooth and easy. More, it makes a cut that exposes less ski base at the edges. Some skiers prefer a skin that's cut that way is it sidehills better. Leaving more base exposed, as with the G3 cutter, can be better if you prefer to side-step up steep-hard sections or encounter short downhills you do with skins still on, and need more exposed edge for snowplowing or side slipping. Personally, I prefer less exposed edge and more skin, so the K2 result was my favorite. Advantage with the old way of cutting (offsetting the skin) is you can pick your own base exposure dimension.

A single edge razor still works for the old style method, and was used to make starter notches in my too-narrow skins so the G3 and K2 would work.
Winner of the skin cutter street duel? I’ll take the G3 for kitchen counter work, k2 when I’ve got a ski vise available or want less base exposed — and I’ll still keep a razor blade handy. Again, remember it’s easiest to purchase skins that are around a centimeter wider than your ski at tip and tail, so you can start the G3 or K2 cutter at the front or rear end of the skin. But with stiffer skin backing, as with most nylon skins, you’ll get a smoother starting cut than you will with fabric backed mohair skins, so starting with nylon skins wider than the ski is not as important as with mohair.
WildSnow.com publisher emeritus and founder Lou (Louis Dawson) has a 50+ years career in climbing, backcountry skiing and ski mountaineering. He was the first person in history to ski down all 54 Colorado 14,000-foot peaks, has authored numerous books about about backcountry skiing, and has skied from the summit of Denali in Alaska, North America’s highest mountain.