Opsak test

How did you place the Esbit into the Opsak? How about the garlic? If you used your hands then it's possible you contaminated the outside of the Opsak when when you closed it. You may be smelling the residue from the Esbit or the oil from the garlic on the OUTSIDE of the Opsak; too faint to detect via smell until you closed it up inside a Ziploc and let the molecules permeate the air inside of the bag … opening it then would give you a high enough concentration to pick up on.

Better: In a room with no drafts, wearing gloves, put the Esbit into a NEW Opsak via a long pair of tweezers/pliers/etc being very careful to not touch the zip area of the bag. Remove gloves, zip it shut. Wash the outside of the Opsak with hot soapy water. Dry it well, and then place inside of a NEW ziploc and shut it.

Even a small amount of a substance, over time, can saturate the air inside of a container enough to notice.

-mox

Excellent points Mike.

What is the protocol for handling your food and an OPSak in the woods?

Those are very good points. The only way to be absolutely certain there isn't cross contamination is to wash your hands before opening/closing the Opsak. Truth be told there are likely mild smells of various kinds all over our gear. Truly a difficult task to maintain a neutral odor on everything.

Greg, that is the crux of the problem of odors in the woods. Your gear may be perfect for any job, but if your procedures for using the gear are flawed or impossible to implement then it doesn't matter.

This is probably why so many people advocate bear-bagging all the time. You can't guarantee odor free bagging but you can guarantee that you'll make it difficult for a bear to reach your food (though of course not impossible).

Also, your body stinks, which means your gear stinks too. Opsaks are great for minimizing odor (so are ziplocs) but nothing is 100% in real world conditions. Even in a lab 100% is unheard of.

My test involves dog kibble and my dog. (A dog's olfactory apparatus is far more sensitive than any human's.) Even I can smell his kibble through a quart ziplock freezer bag. After I put his kibble (inside the freezer bag ) into an OP sack, the dog completely ignored it, something he'd never do if he could smell anything resembling food! The OP sack was not new, either. I use two small OP sacks in my dog's pack (one on each side) to contain the quart ziplock bags with his kibble, in hopes that his pack won't end up smelling of dog food. So far, no issues. (The kibble of course goes into an Ursack at night.)

IMHO, the OP sack is a useful supplement to a hung food bag and an essential part of the Ursack system. At the very least, it cuts the smells way back so that the bag doesn't scream "FOOD" to passing varmints of various sizes.

"IMHO, the OP sack is a useful supplement to a hung food bag and an essential part of the Ursack system. At the very least, it cuts the smells way back so that the bag doesn't scream "FOOD" to passing varmints of various sizes."

A huge +1 Exactly the way it should be done, IMO.

I am a big fan of the Opsaks. I always use one in conjunction with my food bag, which is most of the time a ZPacks Blast food bag (with the cinch top).

I have a trip coming up in 2 weeks, and have slowly been getting some of my food for this trip. I have been keeping it inside my 12 x 20 Opsak, which has been inside a Granite Gear UberLite 10L roll top bag. The Opsak has been sealed shut for about the last week, since I was last in it. I opened it up today though looking for a packet of Emergen-C and wow! I did not smell anything until I opened it up, and when I did…it was like the smells had been waiting to escape! It was definitely a strong smell, and everything inside the Opsak is still in it's original packaging. There is an assortment of bars, some drink mixes, poptarts and some other stuff I can't remember right off the top of my head.

Anyway, like I said, I always use one. I will admit, when I am adding in that 1.3 oz for the Opsak into my spreadsheet, it kind of sucks…but I had rather carry it for a little extra protection. I still hang my food in bear country though.

Does, it work, I dunno…all I do know is that I have yet to wake up to find remnants of my food bag laying all over the place…instead, it is always hanging in the trees right where I left it.

I will admit too though, I do not wash my hands before handling the Opsak, so I know that there has gotten to be smells on the outside too.

"when I am adding in that 1.3 oz for the Opsak into my spreadsheet, it kind of sucks..'

You don't hear that kind of talk anywhere but here!

I put a ziplock back of peanuts in an opsak and place it on the ground in the woods behind my house which are full of squirrels. They never touched it. I placed an open can of cat food in a zip lock and in then in an opsak. I left it on my carport for two days and nights. Nether my cats or the neighbors cats touched it. Also the possums that constantly eat the cat food that we leave out never touched it. At least it appears to work for protection from small critters.

"Your gear may be perfect for any job, but if your procedures for using the gear are flawed or impossible to implement then it doesn't matter."

That's how I see it too.

Simply put, I have had a mouse chew through a brand new OPSak, first night out of Kennedy Meadows on my PCT thru hike while it was in my vestibule. While there is NO way of knowing if I got food odors on the outside of the bag while handling it (and yes I did zip it properly — I'd been backpacking for over two months straight at that point, and had nine days of food heading into the Sierra in a high snow year, you bet your buttons I was a bit food obsessed/paranoid), the real point of it is that the OPSak was as clean and unscented as it was ever going to get at that point! The more meals I pulled in and out of it, the less unscented it would become.

In theory, odor proof, but in practicality it's really hard to keep gear clean — so to rely on them because you've luckily never had a problem, or to put your faith in them because they're advertised to be odor-proof seems a bit eager in my opinion. They are awesome to hopefully reduce the chance that a critter would even take note of your food bag, and I still carry them on my trips for that reason. But I wouldn't be surprised if it happened again, and I wouldn't put all my eggs in that basket without some skepticism and understanding that I'm taking a risk, even if it's hugely less than not using an OPSak in the first place. For me, they're part of a system, not my one size fits all solution.

I like all the backyard testing though :)

I put some smelly peanut butter and fritos in an Opsak, and also in a Zip-lock freezer bag. I was as careful as possible about not contaminating the outside of the bags, certainly much more careful than I could be while backpacking.

I burried both just under the leaf litter, about 10 feet apart, at a campground, and came back two weeks later.

Result: both chewed through and eaten by small-size critters.

There could also be a totally different reason for test failures that no one has brought up.

Maybe, just maybe, critters have learned that the smell and sound of plastic means there is a tasty treat inside! In which case being odor proof or not is useless, because the container itself is attracting animals!

I know my cat will spend hours liking a plastic bag, and that's without food, if she thought there were kitty treats it'd be even worse. We use mice and rats for intelligence tests while raccoons, bears, foxes, and other animals are all known for their wily picnic snatching behaviors. We're in an arms race to protect our food against the wild, and the wild is much hungrier than civilized folk ;)

opsak's are a waste of money to me.

I would have thought the object in practical terms is to limit the smell rather than eliminate it altogether, given the practicality of keeping the thing sterile.

If a critter stumbles across it and it literally nose to plastic, I'm sure there's going to be enough smell to make it worth testing to see if the contents are edible.

I'd just hope that the bags limit the smell enough to make sure that you're food isn't giving off odors that can be picked up from a long distance.

Two weeks in a campground introduces a huge margin of error. Without checking on it every day there's no way to say kids playing didn't find and compromise them.

I wouldn't expect anything short of a locked steel box to last two weeks on the ground.

Edit to add: I doubt anything on this planet is truly odor PROOF to an animal with a nose like a bear, short of a vacuum sealed thermos and maybe even not even that at close range. The idea is to make everything else in camp relatively more smelly to animals. Non habituated animals smell people and say "I'll pass"

Many years back a dog trainer, who was an active forum member, did a series of odor blocking tests using different bags. The OP Sak was the only one the dogs couldn't smell the contents of.

Out of curiosity: Does anyone else on here use an Opsack as their primary means of excluding bears from their food? I was bear-hanging until a triple-crowner indicated he merely put his food in an Opsack and used it as a pillow.

Maybe it was just the amount of guts that method seems to require, but the idea of no more hangs appealed to me, and I finished my GET thru hike with just an Opsack and no issues (in the bear-active Manzanos and Sandias no less).

Anyone else live out on this edge?

Thanks for the posts about the great tests by Mary D and others with the help of our canine friends.

FWIW, here's the thread from a test done last year:
http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=47872&skip_to_post=417575#417575

As noted, I only use the Opsaks for caches and double bag. This way I can be more sure that odors do not get on the outside of the bags. So far, that has worked OK, even when the bags have been hung in Ursacks in the mountains for several weeks before I reach them.

For daily use while trekking, I would be much more leery, and would certainly not dispense with hanging a bear bag just because of the Opsak. I'm surprised by the number of posts about food in tents. I do not allow it even in my pack – the Ursack is strapped to the top of the pack, and not opened until removed from the pack.
Suppose practices have more to do with what animals inhabit the area trekked.

Some time ago, I had a bear keep me up most of the night because of some blueberry cool-aid kept in a Nalgene bottle next to the tent. No more of that.

OP saks don't work if the critter can see the food. Not all animals rely solely on sense of smell to identify food. I'm not surprised the critters in the campground found the 2-week bag and got into the food. Same thing happened to me last year. Add a normal stuff sack around it, and you likely would have gotten a different result. An opaque (i.e. black) opsak would be a nice item to have – curious if it would have produced different results in your 2-week test.

I have doubts about the importance of visual recognition of food for most mammals. Birds have very acute color vision and might break into a transparent, odor-proof food bag if they can see colorful foods, but I don't think a mammal would.

Most rodents are dichromats (they see everything in gradients of blue and green), and a few are monochromats (they see only black and white). The visual acuity of an average rodent is equivalent to a colorblind human with 20/600 vision. Canids and mustelids (i.e., foxes and raccoons) are blue/green dichromats, and have very poor to nonexistent ability to distinguish colors. Black bears are also dichromats, but have demonstrated an ability to distinguish some colors. Humans and birds are trichromats.

I would wager that no wild mammal would break into a clear plastic bag containing odorless plastic models of food, unless it had a habit of indiscriminately breaking into containers of all kinds. I don't think there would be any difference between clear and opaque food bags.

Colin, you're ignoring some important factors in vision though. Reflections. I know raccoons love ANYTHING that is shiny. An old 'coon hunting trap relied on the animals inability to let go of a shiny object once grabbed.

A lot of food wrappers use reflective mylar. Even the worst visioned animals would still notice flashing mirrored surfaces at close range. Especially if they have good night vision. For the more curious of creatures this would be enough to warrant a nibble or two and once the bag is pierced the smell/taste takes over.

If you really are worried. I'd just develop a taste for spicy food. Mammals can feel the burning sensation and for the most part humans are the only species that actually likes it. So keep plenty of chili powder around and even if an animal gets into your pack they aren't going to want to eat too much of your food! Maybe not the most practical solution but I have had a ringtail cat give up on my food bag after it got a taste of that night's thai food leftovers ;)

Here's my theory–if they actually worked, drug dealers would use them in the course of their work. Which makes me think they probably don't work that well.

Maybe they do.

Or at least some do.
the only action here is at 1:30 –

….and good luck trying to find Kovert, or buy a bag.