odor barrier bags
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Billy Ray
(rosyfinch) - M

Locale: the mountains
odor barrier bags on 07/06/2013 10:17:32 MDT Print View

I remember a while back there was a report testing the Opsak with dogs. A lot of debat ensured. As part of that debate I seem to remember a metal foil or foil coated bag discussed that had superior odor barrier qualities. Can someone tell me, was there a consensus as to which bags are likely the best and most practical odor barriers??? And where to buy them?

thanks,

bill d

Ken Thompson
(kthompson) - MLife

Locale: Behind the Redwood Curtain
Re: odor barrier bags on 07/06/2013 11:07:25 MDT Print View

Here is that thread.


http://www.backpackinglight.com/cgi-bin/backpackinglight/odor_proof_bags_study.html#.UdhOqRanqDY

Colin Krusor
(ckrusor)

Locale: Northwest US
Odor barrier bags on 07/06/2013 11:19:39 MDT Print View

I recently looked into this, and bought some foil barrier bags on Ebay. From my recent reading, my understanding is that barrier bags (designed to prevent ingress or egress of odor molecules, oxygen, and water vapor) are engineered in several different forms. From highest barrier (most odorproof) to lowest, I think they go in this order:

1. Aluminum foil bags
2. Metallized multilayer film bags
3. Multilayer film bags
4. Monolayer film bags

The film material and thickness also makes a difference, obviously. A bag that is twice as thick as another is much more than twice as impervious to odor penetration. Depending on the material, a doubling of film thickness can increase barrier performance tenfold or more. My understanding is that Opsaks are monolayer polyethylene film, like a very thick common ziplock. It is no surprise to me that they failed the test described in that BPL article (with the dogs in the locker room). It doesn't make sense to use a monolayer polyethylene bag to seal in food odors. The NyloBarrier bags sold for the same purpose by Litetrail.com are also probably worthless, in my opinion. They are a monolayer nylon film and they have no seal. Rolling the top of a "hard" film like nylon does not produce a seal.

Aluminum foil bags (aluminum foil laminated to heat-sealable plastic film) are several (or many) orders of magnitude more resistant to odor, oxygen, and water vapor penetration than a monolayer bag like an Opsak or NyloBarrier bag. I bought these:

http://www.ebay.com/itm/161050173488?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649#ht_197wt_1255

pouch

It says "mylar" in the title but the description makes it clear that it is a foil laminate, not metallized film. I prefer the stand-up pouch style bags to the flat style.

Billy Ray
(rosyfinch) - M

Locale: the mountains
thanks, but... on 07/06/2013 11:20:50 MDT Print View

Yes, thanks for the link to the thread... but I had no problem finding the thread... but... being lazy... I was hoping to not have to read through a hundred or so posts to get the information...

thanks.

Nick Gatel
(ngatel) - MLife

Locale: Southern California
Re: odor barrier bags on 07/06/2013 12:32:35 MDT Print View

I am not going to rely on an odor proof bag. In areas that are known to have bear problems I just take a canister. Since I am solo I can't risk losing food.

On all other trips I sleep with my food. Small animals and rodents are the problems I experience most, not bears. But I usually get by with a Cuben sack and no odor proof bag. If in an area I know will be problematic with the smaller creatures I bring a GrubSack or a Ursack, but this is generally the exception. Majority of trips require no special food handling.

Eric Blumensaadt
(Danepacker) - MLife

Locale: Mojave Desert
Coffee bags on 07/06/2013 12:33:23 MDT Print View

I have used aluminized coffee bags for TP wag bags in the Paria River before ALL waste had to be carried out. Worked very well.

Just last month I recycled a coffee bag to carry cooked turkey bacon (inside a sandwich zip bag) on a 6 day trip in Coyote Gulch, Utah. No problens with ring-tailed cats or other rodents being attracted to my food bag.

I feel that the coffee smell along with the bag construction helps kill other odors, good or bad. That's why I save a half dozen of them for backpacking.

Billy Ray
(rosyfinch) - M

Locale: the mountains
Re: Odor barrier bags on 07/06/2013 12:47:27 MDT Print View

Thanks Colin,

those look like great bags... I might find a use for those, but.. really, what I am looking for is something a bit larger... the size I would need to line my UrSack... that's what I'm thinking.

bill d

Colin Krusor
(ckrusor)

Locale: Northwest US
Use on 07/06/2013 13:56:38 MDT Print View

"I am not going to rely on an odor proof bag. In areas that are known to have bear problems I just take a canister. Since I am solo I can't risk losing food."

Rely on one? Nick, I'm not sure I understand what you mean. It sounds like you are saying that you wouldn't leave food out overnight in a barrier bag. Have you heard of people doing that? I've never heard of someone attempting to "rely" on a barrier bag for food protection.

I use the barrier bags inside a steel mesh bag (Outsack), which I hang whenever possible. In areas that have bears the barrier bags go into a cannister. When I used an Opsak for the barrier, I observed small animals attempting to get into the food bag on four occasions, and saw signs of their efforts much more often than that. So, they found it somehow, and it seems likely to me that scent guided them to it. It seems reasonable to assume that one could reduce the number of animals that attempt to breach the Outsack by using a better barrier bag inside it. The benefit to that is longer life for the wire mesh bag and fewer animals around camp. I like wildlife, but attracting them to a food bag teaches them to scavenge from humans and promotes close contact, which isn't a good idea for them or us.

Nick Gatel
(ngatel) - MLife

Locale: Southern California
Re: Use on 07/06/2013 14:07:19 MDT Print View

Colin,

I don't think the bags truly work. So why carry the extra weight. Why even spend the time trying to locate something that *might* work. I put my food in inexpensive ZipLoc's or an appropriate bag for freezer bag cooking and hit the trail.

Methinks we spend too much time worrying about the newest trick gear and all kinds of "what ifs."

So while everyone will spend the next week debating this, I am going to hike a section of the AT where the forests aren't on fire :)

Billy Ray
(rosyfinch) - M

Locale: the mountains
thanks Nick on 07/06/2013 14:18:58 MDT Print View

Thanks for you input nick... but it really doesn't address my question... enjoy your trip...

those who are not on a 'trip', I just want to know the best odor reduction bags and where to get them...

let's please avoid arguing... I'm just looking for some straight forward information... I know they are not 100% odor proof, I know many of you don't agree... but that's not what I'm asking form... please...

bill d

Nick Gatel
(ngatel) - MLife

Locale: Southern California
Re: thanks Nick on 07/06/2013 14:22:47 MDT Print View

Okay, Bill.

I apologize.

Billy Ray
(rosyfinch) - M

Locale: the mountains
okay on 07/06/2013 15:23:03 MDT Print View

Nick you are a gentleman, apology accepted.

thank you...

Bill

Craig .
(zipper) - F

Locale: LOST, but making good time
OP Sak on 07/06/2013 17:27:03 MDT Print View

FWIW I've been using OP Saks since 2005 and NEVER had bears or any other critters go after any food stored in the OP Saks. I can't honestly say whether they helped or not but I haven't had problems with animals trying to get my food.