by Stein, Eric's Son
Clothes: The Insulating Layer
In "Clothes: The Base Layer" I introduced the
concept of dressing in layers and discussed options for
the layer of clothing that is located next to the skin.
This layer is called the base layer. The function of the
base layer is to keep your skin dry. The function of the
next layer is to provide insulation and to transport the
water from the base layer to the outside, where it can
evaporate into the environment.
There are several types of material that work well as
insulators when made into garments. The ones that tend
to work best are made of artificial fibers of one type
or another. Sometimes more than one type of material is
used in a single garment. One popular combination is to
use a smoother material on the outside and a softer, more
filamentous material inside. Hence, we see garments with
an outer surface of nylon and materials such as hydrophobic
(water repellent) spun polyester on the inside. In addition,
many of these garments include lycra and spandex to increase
their ability to stretch while maintaining a trim profile.
So called polyester "fleece" comes into its
own as an outer insulating layer. Worn as a top layer
in windless conditions, or an extra layer of insulation
in very cold conditions, it performs admirably. Whatever
you do, however, avoid materials like cotton or goose
down that essentially loose all of their insulating power
when wet.
Because garments made of these insulating materials are
not particularly windproof, they will serve as a final
layer only on warm days, or when the wind is not blowing.
One partial solution to this problem with fleece that
manufacturers have come up with a fleece that has a windproof-backing
layer. Although reducing the ability of the wind to rob
you of your heat, this windblocking layer can interfere
with wicking and is best avoided. It's preferable to wear
a separate windbreaker. The two-garment approach is preferred
because you can remove the windbreaker if you really get
hot and the fleece will wick better by itself.
Several types of garment can be worn as an insulating
layer, but the zip-turtle neck is one of the best for
the torso. The zipper allows you vent effectively, yet
the turtleneck insures you can ward off cold winds on
the back of your neck. Also, when you buy a garment as
an insulating layer, make sure it has long enough sleeves
and tails so that when you stretch while skiing you don't
develop gaps that let in the cold air. Another thing to
consider when buying an insulating garment is that it
will fit easily over your base layer.
One-piece long underwear or bibbed underwear is nice
to ski in because of the way it stretches with you and
because it avoids multiple layers of wadded up clothing
at places like the waist. Women take note, however, such
designs make trail side pit stops challenging.
Since your arms are being used vigorously when you are
skiing you might want to insulate them less than your
torso. You can accomplish this by wearing a vest over
your insulating layer. A thin nylon vest works fine for
most conditions, although a heavier fleece vest may be
needed on a really cold day.
