/ External Frames
Hip Belt (Women)
Both External Frame (EF) and Internal Frame (IF) packs are
typically made of one of four types/styles of fabric: Cotton
Canvas, "Pack Cloth" Nylon, Cordura Nylon and Rip-stop
Here's a fabric that's remained relatively unchanged for close
to 100 years. Canvas is simply a heavy-weight, rough weave cotton
material. Packs made from this material are usually NOT waterproof.
About the only place in Canada or the U.S. you're likely to
find packs made of this material are from the Boy Scouts or
possibly the military. You might also find a number of inexpensive
Oriental packs made from this material. In Europe, with a little
searching, you can find some specialized packs made from canvas.
For instance, one Swedish manufacturer, Haglöfs, makes
a series of hunting packs out of a very soft cotton canvas.
This is perfect for traveling through heavy brush in search
of game - the pack material it is absolutely silent. The canvas
is urethane coated, making it water resistant, but not waterproof.
The pack comes with an integral rain cover.
Due to it's lack of waterproofing and ready ability to absorb
water or moisture whenever the pack is put on the ground, cotton
canvas is not a preferred pack material. Its main advantage
is that it is inexpensive material, and packs made of this material
will also be inexpensive as a result.
"Pack Cloth" Nylon
"Pack Cloth" Nylon (as it is commonly known in the
industry) is a smooth nylon material with threads of equal diameter
running in the warp (vertical) and fill (horizontal) directions.
It's somewhat shiny and slick to the touch. Many packs utilize
this material, and a great number of daypack styles as well.
It's not as popular as it used to be, but it's a perfectly good
pack fabric. The chief advantages of pack cloth nylon are it's
ready acceptance of urethane waterproofing, abrasion resistance,
and excellent puncture resistance. The downside is that it can
be a somewhat heavy fabric when compared to the other nylons.
Cordura is an "air treated" nylon fabric originally
designed by DuPont. It's characterized by a rough, fuzzy texture
on the outside, and a somewhat rough texture on the inside.
By far, it's the most popular fabric in use today for both backpacks
and daypacks. The chief advantages of Cordura fabric are its
abrasion resistance and light weight. It's not as puncture resistant
as Oxford-weave nylon and doesn't accept waterproofing as well,
but it's also a perfectly good pack fabric. (Keep in mind, we're
talking about degrees of difference here. Coated Cordura fabric
is considered "waterproof" just as Oxford-weave fabric
is considered waterproof.)
Rip-stop Nylon is starting to emerge in the marketplace, and
more companies will probably be using it before long. Rip-stop
nylon is easily distinguished by its regular "grid"
pattern of heavy threads sewn in the warp and fill directions
every quarter-inch. The heavy threads "stop rips"
if the pack is punctured or torn. Nylon, when torn, has a tendency
to start unraveling. If you're deep in the backcountry with
no thread or duct tape, a torn pack can present an interesting
challenge in carrying your gear. A torn nylon pack put under
stress by 50 pounds of equipment, can quickly start to come
apart. The "rip-stopping" design of rip-stop nylon
can provide extra protection to help ensure that your pack won't
disintegrate in front of your eyes the first five miles down
the trail. The main advantages of rip-stop nylon are it's ready
acceptance of waterproofing and it's lightness in weight. It's
not as puncture resistant as pack cloth nylon, but just about
as abrasion resistant. However, since rip-stop is typically
used in lighter fabric weights, holes from prolonged abrasion
in one spot may appear sooner than pack cloth nylon.
Of course, not all packs are made of the four materials outlined
above. Manufacturers are always experimenting with new materials.
While rip-stop nylon seems to be appearing in more and more
upscale packs in the U.S., polyester is starting to make an
appearance in some designs. The Lowe "Trekking" series
of packs use polyester in the body of the pack, while their
"Mountaineering" packs use nylon. Polyester has higher
resistance to ultra-violet (UV) degradation. But pound for pound,
nylon is still a stronger material, so it's a trade-off. Some
companies have been experimenting with Kevlar as a pack material
element. Kevlar is typically woven into the fabric to provide
tear resistance if a hole should appear in your pack.
Some thoughts on Nylon Material
A second consideration once you've looked over the materials
used in packs is the "heftiness" of the material.
"Denier" is a measure of the yarn size, or thickness
used in nylon material. Daypacks typically use 210 denier cloth,
while backpacks may use 420, 500, or even 630 denier cloth.
Obviously, the higher the denier, the higher the strength of
the fabric, and the higher the weight as well (which can be
a consideration....). Most of the higher quality backpacks identify
the denier of the material on a cardboard promotional tag hanging
off the pack. Does that mean a higher number is better? Not
There's an additional factor you should be aware of - tenacity.
Basically, tenacity is a measure of the fabric's ability to
resist additional tearing once a tear has started. Nylon is
available in two types of tenacity. Type 6 is commonly used
in packs constructed in the orient and is classified as "low
tenacity", or lower strength nylon (tenacity of 3.0 to
6.0 grams per denier). Type 66 is considered "high tenacity"
nylon, and is much stronger (tenacity of 6.0 to 9.5 grams per
denier). How can you tell the difference? Sadly, there's no
way without lab testing
You'll find most packs to be sewn with 8 to 10 stitches per
inch. The general feeling here is that if the stitching is increased
much beyond 10-per-inch, the strength of the fabric starts to
degrade. Anything below 6 stitches per inch starts to become
suspect in terms of strength. Remember, packs are made of deniers
much higher than you'll find in a tent or sleeping bag, and
close stitching can actually damage the threads used in the
pack material itself.
The majority of pack manufacturers are using plastic "coil"
zippers on their packs these days. A coil zipper is basically
a continuous piece of plastic that's been fashioned into a coil
shape and sewn onto a piece of fabric. The chief advantage of
the coil zipper is that if fabric gets caught in the teeth,
the fabric can be gently pulled out of the zipper without tearing.
This is certainly a consideration since your pack will sometimes
be jammed with clothing, or on IF packs, with a sleeping bag.
Some EF packs may use regular plastic tooth zippers, and these
are certainly okay as well. They won't let go of fabric that
easily, but size for size, they're stronger than coil zippers.
Some really inexpensive packs may use metal tooth zippers. (When
Kelty first started manufacturing packs, they used bronze tooth
zippers on their pockets before the days of the coil zipper.)
It's possible that some of the very inexpensive packs may still
use aluminum or steel metal zippers, which can either rust or
corrode badly when exposed to rain. I don't recommend them.