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Owner Review - Bozeman Mountain Works Cocoon Pullover
Reviewer: Roger Caffin
Weight: 60 kg (133 lb)
Height: 166 cm (65")
Clothing Size: Medium
Email address: r dot [surname] at acm dot org
Home: Sydney, Australia
I started bushwalking (the Australian term) at 14, then took up rock
climbing at University with the girl who became my wife and is my walking
partner. Later on we took up ski touring and canyoning. Winter and summer,
we prefer long hard trips by ourselves: about a week in Australia, up to two
months in Europe/UK. We prefer fast and light in unfrequented trackless
country. We would be out for at least three months a year. Over the last
four years we have reduced our pack weights from 18 - 20 kg (40 - 45 lb)
each to about 12 kg (26 lb), including food, for week-long trips. I designed
and made much of our lightweight gear myself.
I am also the maintainer of the Australian aus.bushwalking FAQ web site
Manufacturer: Bozeman Mountain Works *1
Product Name: Cocoon Pullover
Year of manufacture: 2006 *2
Country of manufacture: unknown
Materials: Shell Fabric: Pertex Quantum Mini-Ripstop
Lining Fabric: Pertex Quantum Taffeta
Insulation: 68gsm ('2 oz') Polarguard Delta
Listed weight: XS: 7.7 oz (218 g)
S: 8.5 oz (241 g)
M: 8.6 oz (243 g)
L: 9.6 oz (272 g)
XL: 9.9 oz (281 g)
XXL: 10.5 oz (298 g)
Measured weight: Large: 270 g (9.6 oz)
Style: Pullover with neck zip
Colours tested: Orange & Blue exteriors, black interior
MSRP: US$190 *3
Review Date: 21-Sep-2007
*1 The Cocoons are made by Bozeman Mountain Works but are normally sold by
BackpackingLight. However, both companies belong to the same group.
*2 The Cocoons we have are from production runs prior to 2007. The version
currently available looks identical to ours but now is called a Cocoon UL 60
*3 This is the 'public' RRP; discounts are available to subscribers to
I have paraphrased the claims listed on the company web site as they seem
devoid of marketing spin and reasonably accurate.
* High collar - a seal against the elements and heat loss.
* Elastic wrist cuffs and waist hem - functional but light seals.
* Drop tail - insulation for your rear end.
* Single chest pocket - small.
* Deep front zip - adds ventilation capability and simplifies taking it on
This is a fairly simple pullover-style top, with a 340 mm (13.5 ") black zip
at the neck, a simple wrap-around high collar, a small chest pocket and
elasticised cuffs and hem. All this is visible in the picture above. The
warmth value comes from the 68 gsm ('2 oz') Polarguard Delta synthetic
insulation inside the shell. While I am describing my bright yellow Cocoon
(size Large), some of the photos will show my wife's blue Cocoon (size
The two companies (Bozeman Mountain Works and BackpackingLight) specialise
in equipment for the ultra-light end of the market, and this pullover top is
one of the lightest around. Of course, all things being equal, the heavier
the top the more insulation capacity you would expect - but things are never
equal. This top uses some of the lightest shell fabric available and some of
the best synthetic insulation available, but avoids having lots of
'features' which just add weight.
Preamble to Field Experiences
From mid-May in 2007 my wife and I spent three months walking several Grande
Route trails in France. While planning the trip we were extremely concerned
about keeping our pack weights down - you may note my age. One thing which
did concern us was the matter of warm clothing, as we had to expect some bad
weather in the three months. In the event we had a lot more bad weather than
we had expected: the season was rather rough, with very late snow and a lot
of cold wind, rain, hail and sleet.
While planning we had a choice of two warm tops: some '200-weight' fleece
tops which I had made and which were quite warm, and these 'padded' Cocoon
tops. The advantage of a fleece top in general is that one can wear it
without damaging it while carrying a pack. I don't think the Polarguard
Delta would appreciate being crushed under a pack for hours of walking on
end, although I don't actually know. However, the 200-weight fleece top is
not as warm as the Cocoon, and it is almost twice as heavy. What eventually
decided us both in favour of the lighter Cocoons was the realisation that we
seldom wear fleece tops while walking: in practice we only do that on ski
trips in bad weather. The trip to France was meant to be a summer trip.
I have since used my Cocoon here in Australia, while camping in the bottom
of a very shady closed-in valley in the rainforest. Once again it made me
I can say quite positively that the Cocoon is warm! If I was cold and wet
when I finally got into the tent in the evening, I knew that discarding my
wet shirt for a thermal top and the Cocoon would quickly bring great
happiness. I would add that some evenings were only a few degrees above
freezing when we settled down to cook dinner - like in the photo to the
right. On the other hand, I did not try wearing the Cocoon with nothing
under it: the fit of the Large on my Medium body is not that tight so a
little draft-proofing was indicated, and anyhow I did not want to have to
wash the Cocoon during the trip. I could wash my thermal top much more
Why did I choose the Large instead of the Medium? Well, one theory was that
having it slightly large would let me pop it on easily over other clothing.
In practice I rarely did that however, as it was normally stored very safely
at the bottom of my pack beside my sleeping bag, in the very waterproof
stuff sack I had made for it. I have this paranoid attitude towards keeping
my final defence line of clothing quite dry - but the weather was very poor
for a long time, and we were quite dependent on our final defense line of
clothing. The other theory said that having the fit too tight would not let
the insulation fluff out adequately. I cannot comment on the latter as the
fit for both mine and my wife's tops were generous.
It is hard to separate out the two issues of warmth and comfort. Obviously a
design which really doesn't fit is going to be uncomfortable, and that did
not happen. Once past that test, I have to say 'if I'm warm I'm
comfortable'! It might have been nice to have had a Cocoon with an
integrated hood, but that option only became available after we acquired
these. The only very slight negative I can think of is that the 'drop tail'
is not particularly generous - but it does manage to cover my waist when I
am sitting down. A Medium might not have been so generous. I will leave it
Synthetic versus Down
This topic is a perennial: which is better? In this case the answer is, in
my opinion, definitely the synthetic, but for reasons which are not so
obvious. The padding layer is about 20 mm, but this is very hard to measure.
Any pressure on the fabric and the Polarguard layer is squeezed thinner.
However, when I am wearing it there is usually little or no pressure on the
Polarguard, so that's OK.
Could this be matched by an equivalent weight of down? If the layer was flat
on the ground I suspect the answer would be yes, but the Cocoon is not flat
on the ground when I am wearing it. I know from experience (making down
sleeping bags) that if I pack a very small quantity of down into a box
structure which is hanging vertical, it is likely to settle to the bottom of
the box. The top half of the box becomes nearly empty, and a poor insulator.
This can be prevented by having very small boxes - which is extremely
expensive to sew, or by stuffing the boxes much fuller - which is heavier.
However, the Polarguard Delta insulation used here comes in a batt which
some structure: it can be hung vertically and retain its shape. Most other
similar synthetic insulation materials behave the same. So in this case I
think the use of a synthetic insulation works best.
Robustness - Fabric and Insulation
This was a concern, as I mentioned above in the Preamble. The fabric is so
very light ... But the Cocoons seemed to survive everything we did to them -
although we were careful. (That goes for both my Cocoon and my wife's.) The
elastic in the hem and cuffs seems the same as when new, and the zip is
still just fine. I admit I was occasionally concerned that the puffy sleeves
might catch in the dinner or, far worse, get toasted by the stove while I
was cooking dinner, but none of that ever happened. Perhaps the cuffs are
not that prone to flapping around.
The robustness of the synthetic insulation is also a concern, and it should
be noted that the manufacturer has recommended that the Cocoon be stuffed
loosely for this reason. We took this recommendation to heart and pack each
Cocoon into a stuff sack I designed and made for it: a cylinder of about 150
mm diameter by 330 mm high (6" x 13"). The Cocoon could be packed down much
tighter than this, but I usually have enough space inside my pack to allow
the Cocoons to be packed slightly loosely. Weight matters a lot more than
volume. That said, I should add that when the Cocoon stuff sack is pulled
out of my pack in the evening it is usually more of a rectangular shape than
a cylinder. I suspect the volume iss slightly reduced thereby.
The Cocoons look very snazzy and we did consider wearing them out to dinner
when we were stuck in a town in FRance and had to stay at a small hotel. But
we didn't: they were too hot!
Maintenance & Washing
I did not find that my Cocoon needed any maintenance on the trip. I did not
get it sweaty at all, so that meant it didn't need washing on the trip. My
wife threw both Cocoons in the washing machine on a gentle cycle when we got
home: they seemed to cope with that without any trouble at all, and they
dried quite quickly too.
I did notice that the fabric stayed fairly clean against other problems,
like bits of food being dropped on it. Food did not seem to stick very well.
I do know that typical fluorocarbon DWR treatments are not only used to make
the fabric water-resistant: they are also widely used to make the fabric
stain-resistant. This seems to have worked here.
The sundries - elasticised cuffs and hem, zip, etc, also survived the trip
very well. I have had no problems with any of them.
Very light No hood (but a model with a hood exists)
Warm Tail could be slightly longer
We both love the Cocoons. My wife enjoys having a light pack these days
compared to the old 'heavy-weight' days, so she tolerates my enthusiasm for
ultra-light gear, albeit with considerable suspicion at times. I asked her
after the trip through France whether she wanted to keep using her Cocoon;
her reply sounded something like 'only out of my cold dead hands'. I think
that is a good final assessment.