FR - O.P. Sak - John R. Waters
- Here is my (John Waters) O.P. Sak Field Report. There is an HTML file
posted in the BGT Test folder at
which includes pictures. Thanks!
Field Report: O.P. Sak
November 1, 2006
Field Conditions/Completed Test Results
Summary to date
Continuing Test Plan
Tester's Biographical Information
Name: John R. Waters
Height: 5 ft 9 in (1.7 m)
Weight: 178 lb (81 kg)
Email Address: exec at bysky dot com
City, State, Country: White Lake, Michigan USA
My backpacking began in 1999. I've hiked rainforests in Hawaii, Costa Rica,
and Puerto Rico, on glaciers in New Zealand and Iceland, 14ers in Colorado
and Death Valley's deserts. I hike or snowshoe 6-8 miles (10 km-13 km) 2-3
times weekly in Pontiac Lake Recreation Area, with other day-long hikes on
various SE Michigan trails. I also hike in Colorado and am relocating there,
which will increase my hiking time and trail variety tremendously.
My daypack is 18 lb (8 kg); overnights' weigh over 25 lb (11 kg). I'm aiming
to reduce my weight load by 40% or more.
Product Information and Picture (from manufacturer's website)
Manufacturer: Watchful Eye Designs
Style: O.P. Sak
Sizes and MSRP:
O.P.SAK NEW 9 X 10 3-PACK $7.79
O.P.SAK NEW 12.5 X 20 3-PACK $10.59
O.P.SAK NEW 28 X 20 2-PACK $13.29
Features: New durable O.P.SAK 100% odor barrier bag. No gusset. Store food
undetected at the camp site. OK to add boiling water to the O.P.SAK to
prepare food as the film is FDA approved. You can not place the O.P.SAK in
boiling water. The O.P.SAK uses the same seal as the ALOKSAK and offers all
of the same air and water proof features. If you need a storage and
transport bag that is tolerant to extreme heat, the O.P.SAK is the bag for
Product Information (from tester)
One-package of Three: 12.5 X 20 in (31.75 x 50.8 cm)
One - 28 x 20 in (12 x 50.8 cm)
Three - 9 x 10 in (22.86 x 25.4 cm)
One - 6.75 x 6 in (7.14 x 15.24 cm) (this is NOT an O.P. Sak, but an Alosak)
For an in depth description of the O.P. Sak, please refer to my Initial
Field Conditions/Completed Test Results
I used these bags over the course of several weeks, both camping, hiking and
traveling on airlines, in my backpack, my carry-on and in checked luggage.
Since I had different sizes, I used them for a variety of content material
and even used a bag in an outdoor test for four days in hot sunlight exposed
to the elements on the ground next to a grocery store resealable bag for
comparison (see pictures).
The outdoor test involved using a regular store-brand "freezer-type"
resealable bag and the 9 in x 10 in (22.9 cm x 25.4 cm) O.P. Sak. Nothing is
much more fragrant when warmed in the sun then extra buttery microwaveable
popcorn packs, so I placed one in each bag. The bags were then placed on the
ground in a desolate location in southern Colorado where I could monitor
them during the week. The O.P. Sak showed no signs of moisture entering the
bag or any signs of bugs. Neither attracted any other animals as well, even
though there is plenty of wildlife at this location. It was interesting that
when I opened the O.P. Sak at the end of the test, there was a rush of
moisture into the bag and the popcorn did get wet. I left the popcorn pack
inside the O.P. Sak and carried it around as I traveled for about 6 weeks.
The oil from the popcorn pack did stain the O.P. Sak and I was not able to
remove the oil from the inside of the Sak. I used dishwashing soap, soaking
it for a few days, but this O.P. Sak itself is now not useable for any other
foodstuff since it retained the popcorn butter smell inside and is coated
with the oily film.
After five hot sunny days at 95 F (35 C) with changes to cool 45 F (7 C)
evenings, the regular grocery store resealable bag was infiltrated by ants
and condensation and the popcorn bag started to show signs of butter inside
the bag due to the moisture.
In fact the ants ate their way into the regular grocery store resealable
bag and the bag started to fill up with water from evening thunderstorms. So
when I held the bag up, the corner leaked water. The popcorn pack was not at
all useable. A regular grocery store resealable bag was no match for the
O.P. Sak in this test.
The O.P. Sak, although covered with mud and rainwater, was completely dry
on the inside and the popcorn pack was completely useable.
I used another O.P Sak to hold ground coffee. Loose ground coffee. This was
a new Sak the same size as the one I used for the popcorn pack. Again, this
was taken hiking, overnight, into the desert, on airplanes, into motels,
checked luggage and carry-on. It never broke its seal and it kept the coffee
fresh and dry for 6 weeks. However, I think this bag will not be useable for
other foodstuffs either. I think it would be exceptionally time-consuming to
clean this out and get rid of the coffee odor and to remove the fine coffee
dust that is clinging to the side of the bag. So when the O.P Sak is
designated "reusable", it appears that the items placed in the bag need to
be in their own containers, or that the contents be the same for each use.
"Patented Leakproof/Airtight SEAL" is what the label says on the O.P. Sak.;
"tested and approved by the Navy Experimental Unit" and I can see, after
testing these, that they will keep dry stuff dry under extreme conditions.
However, my tests with liquid INSIDE the bag did not go well. Yes, when I
blew them up like a balloon I could pop them open and, yes, when I filled
one up with water and pushed down real hard it also popped open and sprayed
water all over. Actually they will pop open with water in them without a
whole lot of pressure. I found that out by filling a bag 1/2 full with water
and placing in my backpack. Fortunately, just in case, I also encased the
bag inside a garbage bag, so it leaked into the garbage bag and not my pack.
Had that been human waste or other gooey material my bag would have been
rather messy. The seals seem very lightweight and not rugged enough to
handle say a drop to the ground or a fall on my pack that may crush the
O.P.Sak inside my bag. I also discovered that once the seal is broken and
leaks liquid, the seal becomes less effective. I would need to dry the
entire seal to get it to be as effective as when I first used the bag and
that is quite a task to do quickly.
Just as an experiment, I obtained a BioHazard bag from the local hospital.
Other than the fact that it has a red BioHazard label on it, it looks just
like a grocery store resealable bag and isn't even as heavy as the new
freezer bags being sold today. I don't know what they do that is different
with these bags, but I filled the bag with tap water and turned it upside
down so the zippered top was down and pushed it into the side of the bathtub
as hard as I could. Really hard and it would not open. I took both hands and
squeezed and not a leak. I did all but step on it and it would not leak or
Now I tried the same thing with the O.P. Sak. Filled it half full with
water, and rubbed it against the side of the tub in a circular motion to try
and simulate moving around in a backpack. The seal broke within a minute. It
was a gentle break, not a pop that squirted water all over, so it would have
been a "gentle leak" but it did not take long to get water to come out of
the O.P. Sak.
Just for kicks, I also filled up a cheap freezer bag half way with water and
did the same thing and it popped open in 10 seconds spraying water all over
These are great bags to use for dry foodstuffs and fragrant material. I
would have no issues with putting dry food in these and being assured that a
bear would not smell a thing. Of course, like always, if the smell gets on
my backpack when I'm getting material out of the O.P. Sak that's a different
story. If I transfer the smell to the outside of the Sak there is nothing I
can do to mask the smell. I was very impressed with how well it kept things
dry. They are very waterproof and do not allow water IN. I would not use
these for storing liquids of any kind and would only use them for human
waste if I were to encase it in another container, perhaps a second O.P.
Sak, because although they don't allow the odor out, they do not contain
liquids inside the Sak from leaking out as well as I would want a bag to.
Continuing Test Plan
Over the next few months I will use these Saks extensively to hold
foodstuffs and I will even try to store some less than liquid material, such
as peanut butter. The Sak filled with coffee will continue to be transported
and reported on. These Saks will be getting quite a workout during an
extensive travel and hiking schedule. I am interested in seeing how they
wear now, since I am seeing signs of creases and folds, none of which affect
the performance yet, but these additional tests will stress them out even
I will also report any other issues that arise during the testing period.
Thank you for the opportunity to test this product!
John R. Waters