Food/Bear Can Musings and Questions

Btw, you can get these type of bags, easily and fairly cheaply, up to 5 gallons more commonly–they are quite large and can fit a lot of food in them.  The plastic film thickness may vary from source to source.  Typical are 4 to 10 mil range.  Obviously 10 mil will be more durable long term and more puncture resistant.  But again, to stress, the real barrier is the inner Al layers (very good gaseous barrier), and these need to be folded over at least twice and tightly at the top to get a good seal, and then well secured.

Can we take a DCF dry bag (which should have mylar) and then have some aluminum foil (much thicker ones than Reynolds alum foil) surround the food before placing it in the DCF dry bag?

If the sides and bottom are folded over and taped with Al tape, and again the top is sealed well, then yes, that would work too. But Al foil is fairly fragile unless it is significantly thicker than kitchen/home use stuff, which is part of the reason why it is sandwiched between plastic films (that and so one can heat fuse the plastic together forming a very good seal).

“Once your food is properly sealed in a mylar type bag with a sufficiently thick aluminum foil sandwiched in between the plastic layers, then the bear will NOT be able to smell the contents within that bag. They may smell scents on the outside of the bag from handling, but these of course will be faint/weak compared to the concentrated scents within the bag.”

Sure…. but… once the bear gets to that bag with the smell ‘only’ on the outside, it will be easy for the bear to open… even if it’s in the tent… the bear will go through your defense like a hot knife through butter… bears are very quiet… you will not have time to find your bear spray in the dark and aim… and if you do, you will spray yourself also… and/or scare the bear and then he takes swipe at you… claws go though skin and flesh like a hot knife through butter… why take this silly risk and endanger yourself and the bear’s life… canisters work… no stress… no risk… and sleep secure…

Maybe I should start a new thread instead of hijacking this one?  It is a different topic, since as far as I remember none of the attacks, with one possible exception, involved improper food storage.

Aren’t all off the shelf freeze dried backingpacking meals packaged in industrially sealed aluminized mylar bags? And they back fill them with inert gas to lower the pressure differential across the bag material minimizing the forces pushing molecules through.

This is how most people today bring food into the backcountry; and all of everyone’s experience says to put said food bags into bear protective canisters or hanging systems.

Keep in mind that bears also use visual ques to detect food.  I have seen bears go after plastic grocery bags as they “know” that there is probably food in them.  I am pretty sure that they know what an un-openned bag of chips look like as well.  I don’t think that a selaed mylar bag is going to stop a bear from thinking that there is food inside.  My 2 cents

Don, that is thoughtful. As a moderator I appreciate the thought to fork the conversation about those attacks into a different thread. Thank you.

Once again I find myself agreeing with DWR. The simplicity of a bearcan is really nice but it has traditionally come at the expense of a less comfortable pack. I’ve mentioned this elsewhere but I think the BV425 is a total game-changer. I love being able to put the flat side against my back. There’s no barreling and I can get the weight right in the small of my back like I can with a bear bag. My pack is light enough that I don’t really care about the 28 (?) ounces. I hiked with it in my Kumo earlier this week and it had that perfect melting into my back feeling. I’m sold for any trip where 5 liters of storage is sufficient.

Matthew… the BV425 is an interesting solution… short enough you can put the flat side toward your back, is what I assume your are saying. Also, did you know that Wild Ideas will custom make their carbon fiber Berikade to any length you want? There is a custom length order option on their web page. Expensive, but another option.

The question isn’t really about whether bears will attack and hurt people, although that’s important. It’s about whether bears will successfully get human food, something I hope we all know it’s critical to prevent from happening, not just for our own sakes.

I’m sold for any trip where 5 liters of storage is sufficient.

Do you actually have one pack for 5 liter or less of food and one for more than 5 liters?  Just curious.

“Aren’t all off the shelf freeze dried backingpacking meals packaged in industrially sealed aluminized mylar bags?…

…This is how most people today bring food into the backcountry; and all of everyone’s experience says to put said food bags into bear protective canisters or hanging systems.”

Correct on the first part, but context is important. When the freeze dried food bag is originally sealed, indeed, it will be invisible (odor/scent) wise to bears.  Once you open it is the issue.  How many people reseal these back up meticulously whether they have food left or especially once it is empty?

For resealing any mylar bags if you want to cut down on odor diffusion, you have to have the inner aluminum foil fold over itself (preferably more than once) and tightly, and have it stay secured like that the entire time.  This is probably too much faff for the average, especially non BPL minded (lets face it, we tend to be kind of geeks and/or a little OCD compared to the typical) type hiker/backpacker. It’s not for me, and therefore I feel comfortable with this method/technique.

Again, I don’t care what others do or don’t do.  I’m not trying to convert people, but sharing information that I’ve not seen talked about before.  If I hadn’t done so much recent research into vacuums and vacuum systems, I wouldn’t have been aware of these facts and data either. The physics involved are very much applicable to this situation i.e. summed up in: with no to extremely small amounts of gaseous exchange, there will be no to extremely small amounts of odor diffusion.  Yes, it is that simple and that fact can and imo, should be, taken advantage of.

“Keep in mind that bears also use visual ques to detect food.  I have seen bears go after plastic grocery bags as they “know” that there is probably food in them.  I am pretty sure that they know what an un-openned bag of chips look like as well.  I don’t think that a selaed mylar bag is going to stop a bear from thinking that there is food inside.  My 2 cents”

Compared to many other wild animals, bears don’t have particularly good eyesight. They are somewhat nearsighted and their vision is relatively comparable to humans with average eyesight but with far worse peripheral vision. They are not going to make out details from a distance very well. And compared to their sense of smell, their vision is shite.

But I don’t doubt they are intelligent enough to use visual cues and learn to pattern recognize via all their senses (nor do we fully and completely understand animal instinct.  For example, how do flocks of birds know how to suddenly change direction in flight all at once like they share the same hive mind?).  But the point is, their sense of smell is their predominant and keenest sense by far, and making food relatively invisible to that sense will go a long way to making food far less detectable to them in general.

I backpack mainly in the Sierras, many times in Yosemite NP. The bears there are exposed to a lot of stupid humans and are adept at visual clues. In the backcountry, I have seen them walk by bear canisters as they “know” that the effort/calorie is not very good. I have seen them grab and run away with plastic grocery bags full of stuff: high probability of good stuff being in there. The rangers caught a bear that was breaking into cars, unlocked cars. They figured out the visual clues to what cars were unlocked and used their tongue to lift the handle and open the door.

Yeah, my cat chews on thicker plastic bags but not thin ones. I had to put a kid proof lock on a cabinet to keep her away from the bags. She doesn’t eat them, just punches her teeth through them.

their sense of smell is their predominant and keenest sense by far, and making food relatively invisible to that sense will go a long way to making food far less detectable to them in general.

I’m of the opinion that you can’t hide the smells.  Even if you really have a smell-impermeable container (which I doubt is achievable at a weight backpackers will tolerate), the smell of food and of you are all over the outside of it.  And bears smell you in your tent and know your food is somewhere nearby…eagle vision not required.

You don’t keep a bad guy out of your house by hiding the door; you have to make the door strong.  And you don’t keep a bear out of  your food by hiding the food; you put it where the bear can’t get it.

My 2 cents.

“Even if you really have a smell-impermeable container (which I doubt is achievable at a weight backpackers will tolerate),…”

Did you miss all the previous about vacuum insulated panels and the materials used?  The gas/moisture barrier is naught but a relatively thin aluminum foil sandwiched in between relatively thin layers of plastic films.  Did you miss that some of these are rated to hold a vacuum successfully for 25 to 50 years (when properly designed and with the right getters helping?

Mylar-aluminum bags are not particularly heavy. They are a bit heavier than Opsack and nylofume bags, but nothing close to being generally heavy.  They are far, far, far lighter than bear containers and significantly lighter than Ursacks.

“..the smell of food and of you are all over the outside of it.  And bears smell you in your tent and know your food is somewhere nearby…eagle vision not required.”

As to the first part, exactly!  As I mentioned earlier, no matter what you do or don’t do, you will have all kind of potentially interesting smells on and near you that bears can pick up. To the second part, as also mentioned earlier, bears have such an acute sense of smell and high enough intelligence to run risk assessment for obviously larger sources of food.  And if that obviously larger source of food is being odor blocked from them, why would they go after what they normally associate with residual and indirect smells rather than concentrated, direct larger food source smells?

This is all about relative risk assessment. Most of us drive around in cars–one could easily call these death or injury machines based on the amount of accidents with deaths and/or severe injuries linked to them every year. I’m not going to stop driving a car based on that X amount of people a year die in relation to them.  Putting your food in a scent impermeable container is better than buckling up, driving fully sober and carefully/defensively when driving a car, in relation to risk to bears.  The physics and logic is sound, but it requires balanced, holistic, and nuanced reasoning.

Maybe if a crap ton of people started to use mylar bags and did so for a long time, then maybe Jon’s potential of bear’s visually associating those particular bags with food could come into play. Until that starts to happen, personally, I would feel completely comfortable with using the scent blocking method in places that don’t legally require canisters and ursacks.

Most of us ultralight backpackers reseal freeze dried food into ziplocks:-) those bags are extra weight and bulky.

The bear expert Stephen Herrero says that he triple packs food into plastic bags and keeps it far away from his tent – has never lost his food. He doesn’t use the term “opsak” as it was probably not available during the time he wrote the book – which mostly describes events that happened in the 70’s through perhaps early 90’s. Much of what he writes about encounters were when bear proof containers were not used in parks/cities etc and bears knew where to get easy food – from open garbage pits in parks/cities. All of that has changed now of course with parks/restaurants/cities with bear proof containers etc.  Anyways, he also talks about many occasions where people did all the right things and still got mauled or bears entered tents etc. I mean – it is all random. Sure reducing food smells are important – but, as I said, mnay encounters are pretty random. Most are from surprising bears on the trail or when they are protecting their cubs or their kill.

Where there are habituated bears, I don’t think it matters if food smells are the culprit, bears can smell humans and know they have food and they are going to mess around irrespective of what you do. So, in Yosemite you dont want to put food in your tent – bear cans are anyways required. Where there are no habituated bears, it is a lot safer. Take for example, Philip – BPL member who backpacks in Alaska – his videos show him eating inside his tent and when I asked him if it wasn’t dangerous in Alaska with grizzly bears around – he said most of the bears are scared of humans there in Alaska and want to avoid dirty humans. He obvioulsy is an expert backpacker with lots of experience with food storage. In another hunting video – he showed how they protected unattended food overnight with electric fence as they hauled meat to their cars etc. Then there is Jupiter hikes – who has hiked more than 12K miles. He was doing a PCT thru in 2022 and near the Tahoe rim trail area (which he has done before), as he was packing up to leave one morning, he encountered a bear some 10 feet from him and that spooked him a lot. You can see the scared look in his eyes and how rattled he was for the next 2 hours or so. This is a guy who has backpacked 12k miles.

In habituated areas, do all you can – take a can. In areas where bears are not habituated, you have more leeway.

Did you miss all the previous about vacuum insulated panels and the materials used?

I didn’t miss any of that.  I just don’t believe such containers would survive all the open/close/handle/stuff/pack cycles of a typical trip and certainly wouldn’t survive even the fleeting curiosity of a bear.

Alaska is a large place, larger than most people can imagine. Philip is in Kodiak, 500 miles from me in Fairbanks. Kodiak bears are so different than our bears in the Interior, starting with size alone! So you can’t really discuss “bears in Alaska” – you need to discuss the precise location, the use of the area by people, the number of bears, etc. If I were going to Kodiak, I’d not assume I know the climate, the weather, the bears, etc. It’s like a different state.

In our State Parks, bear canisters aren’t required, but I predict that some day they will be, thanks to poor human behavior. People following dubious advice in 2021 stored their food in their tent on the Kesugi Ridge trail – a trail that was pretty much unknown outside Alaska until some YouTuber publicized it. Now it’s a veritable sea of humanity most of the time. The people were outside their tent, the food inside. The family’s tent was shredded, the bear got the food, and now everyone using that area risks potential unhappy bear encounters. Bears have gotten food on other popular trails in the area as well. There is so much more use by humans now, most of whom are careless about their impact on the land and the wildlife, or don’t know what they are doing. There is no permitting process, no registration of use, no law enforcement. No posted rules, no information provided before people set out on trail.

In other areas of Alaska, there have been many food/bear problems, especially in the cities of Juneau and Anchorage. Any recreational areas near those cities may also have bears habituated to human food. Bears are typically shot here when problems occur, none of this capture and release stuff. Some people using the backcountry just use the gun as the chief method of keeping bears out of their food and don’t bother at all with storage methods.

Denali National Park requires bear canisters. Please please, don’t wreck it for all and just carry one there. They instituted the policy of managing humans not bears and it has been very successful.

I didn’t used to carry a bear canister on most of my backpacks up here, on state park land, BLM land; now I do. All it takes is one encounter and that bear will forever know how to get food from people. Foolish behavior puts everyone – and most of all bears – at risk. Anecdotes about how one person has never had a problem aren’t the best way to measure effectiveness.

“In habituated areas, do all you can – take a can. In areas where bears are not habituated, you have more leeway.”

Yep.

Would also add that a highly bear populated area doesn’t necessarily equal a habituated area.  I most often hike in or very near a national park that has one of the highest bear populations per area on the US east coast.  The park recommends a bear canister but doesn’t legally require it, and also recommends tree hanging or using the bear poles at the AT shelters.

But for me, it is even less an issue since I hike most from mid-late fall to very early spring, with my most preferred time being in winter.  I prefer the cold over heat, and bears are hibernating during a good portion of the above time.  When it is early spring, I take more precaution because not only are the bears potentially out and about, but also very hungry!   But despite the fairly high bear population, I rarely ever see them–they are fairly shy around these parts, though I have heard of them showing up more in established camps (vs AT shelters).  There are rumors to possibly be mountain lions, but the park won’t confirm.  To be honest, I’m more wary mountain lions than the black bears around here.

Anyways, thanks for chiming in.  I’m going to be bowing out after my next reply because I’m getting to the point where I’m repeating things I already said.

AK – can you tell me if you will carry a bear canister on the entire PCT?

“…I just don’t believe such containers would survive all the open/close/handle/stuff/pack cycles of a typical trip…”

This is potentially a valid concern. I’m not sure what a typical trip is though. Are we talking AT, CT, PCT, CDT, or what?  These are all pretty different from each other.  Or are we talking about your typical weekend trips?  I don’t know for certain, but I suspect that probably the most common type trip, numbers and frequency wise, are weekend trips, followed by 3 day “weekend” trips (i.e. a holiday following/preceding a weekend, or an extra day taken off).

But to more specifically address your concerns, mylar-aluminum bags come in a wide range of thicknesses.  Most common range seems to be from 4 to 10 mil.  But, you can get 12 mil (and even occasionally 15 mil).  Once you get near 10 mil, you are talking some fairly durable material–especially for weekend and extended weekend trips. As to thru hikes, I don’t know what thickness one would need on average to survive them and stay in good shape. I suspect a lot depends on how you treat and pack it like a lot of other gear. But, as long as the inner aluminum layer stays intact, you will have a very good scent barrier.  Aluminum foil is a much, much better scent barrier than mylar/PET and most other commonly used plastics used for containing food and/or beverages (PE, PP, PVC, etc).  The aluminum foil is being protected by the outside plastic film.

If you get a puncture through the plastic film AND the inner aluminum layer, then you will be more so SOL and need to not use that bag anymore.  But if you’re using a 12 mil bag, that certainly won’t be easy to do.

Well, cheers, HYOH/YMMV, and all that jazz.

I’m not doing the PCT. I did carry one the whole TRT.  It just isn’t that big of a deal to carry.

AK – you are avoiding the question. Speculate on what you would do if you did the PCT – will you carry a bear can the whole trip as there are bears all along the PCT. The question is important to answer as a thru hiker hiking for 2500 milies makes different decisions than a hiker who is doing just the TRT. It is easy to say carry a bear can – but a different thing to be able to do it based on the types of hikes, hikers do.

Why the hell should I answer your question? I don’t need to speculate on something I don’t intend to do. Figure it out yourself. Most critically, don’t feed the bears.