Survival Basics: What the Heck are Oxygen Absorbers?

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When I first started getting serious about food storage, I found myself facing an entirely new vocabulary of food storage terms.  It should come as no surprise that one of those terms was “Oxygen Absorber”.

Now I am pretty sure that you have heard about oxygen absorbers.  But do you know what they are and that they are a necessary component when sealing up dry goods for the long haul?  Oxygen absorbers are a mystery to many so today I will provide you with the basics – just enough to get you started on the road to storing your bulk foods for the long term.


Learning about Long Term Storage

The very first item I purchased for my food storage pantry was a 25 pound sack of pinto beans.  Of course back then, I thought I would simply store the big bag in the garage and let it sit there until I needed it – you know, set it and forget it.  Luckily, I did my research and learned first and foremost that beans indeed have a shelf life and will turn as hard as rocks if not properly packaged and maintained in a cool, moisture free environment.  Who knew?

The light bulb really came on as I was reading John Hill’s book How to Live on Wheat.  It was this little book that taught me not only about wheat (living and dead) but about storage containers, Mylar bags, desiccants, and yes, oxygen absorbers.  Seriously, I wanted – no, I needed – to know what was in these little packets and how could I learn to use them effectively for long term food storage.

What are oxygen absorbers made of?

Oxygen absorbers are smallish little packets that hold an iron powder.  Through the magic of technology – or so it seems to me – the outer wrapper lets oxygen and moisture in. At the same time, the outer wrapper is strong enough to prevent leakage of the the powder back out into the packaged food.

How to they work?

In the process of sucking up moisture, the iron in the absorber starts to rust.  This creates oxidation and before you know it, in a well sealed container, 99.99% of the oxygen is used up.  Any space or air left in the container is nitrogen – not oxygen – which is not a bad thing because insects can not thrive in pure nitrogen.

So, in simple terms, the little packet sucks up all of the oxygen from the air within the container in which it is placed.

Factoid:  Air is about 21 percent oxygen, 78 percent nitrogen and 1% other gasses.  Did you know that?

What about storage containers?

Still with me?  We are getting to the hard part.  As you do your research, you will hear over and over again that you should use oxygen absorbers in sealed Mylar bags.  And yes, it is true that they work extremely well when used with sealed Mylar bags.

But – and this is a big but – they can be used successfully to block out oxygen with other types of packaging, too.  All of the following will work:

Metal cans with sealed lids.  Great if you have access to a canner or a local community kitchen.  For most of us, however, this is not a realistic and cost effective solution

Mason jars with proper canning lids.  This is one of my favorites especially since I have a special attachment for my food saver that allows me to vacuum seal the mason jars quickly and easily.  And, just a personal thing, but I love looking at all of the products peeking out of those glass jars.

Mylar bags. These are heavy duty foil bags lined with a special plastic.

Vacuum sealed bags (such as the Food Saver bags).  While not as heavy as the Mylar, these are much easier to handle especially if you already have the Food Saver machine itself.

Plastic buckets with gamma seals.  These can be used alone or in combination with other Mylar or other bags such as those from the food saver.

PETE plastic bottles with airtight, screw on lids.

What is the proper way to use oxygen absorbers?

There are just a few precautions that you need to be aware of when using oxygen absorbers.

The most important precaution is to limit the unused packets from exposure to the air.  Take out only what you are going to use in the next 15 minutes or so and seal the rest up in a jar with a screw top lid.  Don’t put them in a zip lock bag because they will immediately suck up the residual oxygen and become useless.

A good rule of thumb is to use one 300 cc oxygen absorber for each gallon of product.  For larger containers, you can purchase larger, 2000 cc oxygen absorbers which are ideal for 5 or 6 gallon buckets.

Be mindful of the little pink pill.  Most reputable vendors will include a little pick pill with their package of absorbers.  If the pill is blue, the absorbers are toast so don’t use them.  However, if they are just starting to turn – not quite pink and not quite blue – they are probably okay since the change of color can happen in as little as 10 or 15 minutes.

Another good test of their viability is to pick one up an hold it.  It may feel warm.  It will also feel soft and powdery, like a little pillow.  If it gets real hot and uncomfortable, it is in full out working mode and has probably been exposed to the air for too long to be usable.  In this case it may also start to feel hard and brick like.  Toss it.

Oxygen absorbers themselves have a limited shelf life, even when sealed.  Only purchase an amount that you will use within a year.

Help Me! I Am Confused!!!

If you start to do some research on your own, prepare to be confused.  You will find that some sources feel you should use a larger quantity of oxygen absorbers when packaging dried pasta and beans versus packaging grains, flours, and rice.  The reason for this is that the latter are more dense so there is less oxygen to get rid of.

You can come to your own conclusion but the overwhelming advice I received from respected vendors was that 300 cc’s per gallon or 2000 cc’s per bucket would do just fine.

A few other pointers

Almost anything can be packaged using oxygen absorbers and they are so inexpensive, there is no reason not to use them.  There are some things, however, that should be packaged without them.  They are sugar and salt.  Why?  Well the sugar will turn to a brick of concrete and the salt simply does not need anything special to keep it preserved.  It too may clump.

In addition, sprouting seeds need oxygen to stay alive (and ultimately germinate) so you would be defeating your purpose if you sealed them up with an oxygen absorber.

A bag sealed with product plus an oxygen absorber may or may not turn brick like in a day or two or even up to a week.  The ability to fully compress is dependent upon factors such as head room and the amount of air that was sucked out during the sealing process.  This is not a problem in spite of what you may read on the internet.  If you have used an oxygen absorber sufficient for the size of your packaging, the oxygen will be gone.  The extra air is simply nitrogen and it will not harm your food.  Of course, if it makes you feel better, you could open the package and start all over again but that is not really necessary for anything but your peace of mind.

The Final Word

Using oxygen absorbers (or Mylar bags, a FoodSaver or even buckets) does not have to be a big mystery.  All you really need is someone to explain it to you, right?

Seriously though, my eBook, The Prepper’s Guide to Food Storage, covers what food to store, how to store it and a whole lot more.  For the basics, though, keep checking back as I will do my best to explain the mysteries of food storage – in very plain terms – here on Backdoor Survival.

For an interesting technical discussion of Oxygen Absorbers, read A Guide to Oxygen Absorbers.

Enjoy your next adventure through common sense and thoughtful preparation!

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Bargain Bin: Here are some of my favorite food storage items. Whether you are just getting started or a seasoned pro, here are the items you will need when purchasing food in bulk for long term, SHTF needs.

Mylar bags & Oxygen Absorbers: What I love about Mylar bags and oxygen absorbers is they protect against every single one of the food storage enemies. Prices do vary but for the most part, they are inexpensive and easy to keep on hand.  The easiest way to seal the bags is with a cheap hair straightening iron that you can pick up $20 or less.

60 – 300cc Oxygen Absorbers: This is one area where you want to make sure you are getting a quality product. Currently, a pack of 60 (in three 20 unit packs) is about $10 with free shipping.

Mylar Zip Seal Food Storage Bags The Sunday Survival Buzz   Volume 22: These are the zip seal bags that I used to package up my spices, herbs and butter powder. These are extra heavy, 5 mil bags. I found that the zip feature made packaging extra easy although I still seal the bags with my hair iron.

Nesco 600-Watt Food DehydratorThis modestly priced dehydrator (less than $60) has over 1000 reviews and comes up as the most highly rated dehydrator on Amazon.  I wish I had started out and learned the ropes with this unit rather than the more expensive Excalibur which did not work out for me.

FoodSaver Vacuum Sealer: As long as the unit has an accessory port (and this one does), and inexpensive FoodSaver will work just as well as the fancier models. That is my two cents, at least.

FoodSaver Wide Mouth Jar Sealer: Already have a FoodSaver? If so, check out this jar sealer which can be used to vacuum seal your Mason jars. This is a great option for short to mid term storage of items such as beans, rice, sugar and salt. Store your jars in a cool, dark place and you are set with the added advantage of removing a small amount for current use without having to disrupt your large Mylar bag or bucket of food.  There is also a version for regular sized jars.

DIY Superpal Combo KitShop the Emergency Essentials Monthly Specials: The monthly specials at Emergency Essentials feature discounts of up to 35% off sometimes a bit more.

One item I can recommend available is their Do It Yourself Super Pail Combo. It includes 8 x 6-Gallon Buckets with Lids, 8 x Metallized Storage Bags and a 10-Pack of Large Oxygen Absorbers.

Don’t forget that you do not need fancy equipment to seal the metalized bag. A cheap hair iron will do the job.

Storing Rice in Mylar Bag_09

Conair Flat Iron 2″ Ceramic Straightener: I use a hair iron to seal my Mylar bags. Forget about a hose and a vacuum sealer. A $20 hair iron works great and is so much easier than using a clothes iron.


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Survival Basics: What the Heck are Oxygen Absorbers? — 29 Comments

  1. Why are mason jars that are vacuum sealed short term storage? And do you need to use a vacuum sealer if you are using an oxygen absorber in the mason jar?

    • Marilee – Using a vacuum seal on your jars will ensure that the lid is properly sealed down tightly so that no air intrudes from the top of the jar. As a matter of fact, once sealed in this manner, you need a spoon or other tool to pry off the lid. It will be extremely tight.

      There is no reason your sealed jars with an oxygen absorber could not be used for long term storage. The oxygen absorber is simply another layer of protection.

      On the other hand, for short term storage (one or two years), there is no need to use an oxygen absorber since your food will remain fresh for a few years on its own.

    • Actually, it is because vacuum sealing doesn’t get all of the oxygen out of the jar. So some say they aren’t for long term,10+ years, storage. However, the amount of oxygen in the air is around 20-21% and if you removed most of the air from a jar there really is very little oxygen left. So personally, I don’t worry about it.


  2. thanks for the info. I have been wondering the whys and wherefores of oxygen absorbers. With respect, I still don’t see a reason for using them. My food storage is completely turned over within a 5-7 year period and I have never had a problem unless it in my learning phase AND the experiments as new technology came onboard.
    I used to store in metal cans, fortunately food grade plastic was developed although the shelf life of these isn’t known, living in the Pacific NW where humidity plays a big part in storing stuff, my cans corroded faster than what I put in them.
    I learned to use food and/or spices to do the work since I store those too. I use sugar, salt in a sock bag plus some bay leaves and peppercorns have worked for me these 40 years; so I will continue to do so until I am given something better. (Not saying anything bad about ‘absorbers’ just that if there is one thing I’ve learned in my 60+ years, it’s that not all that is ‘new and improved’ beats what has been traditionally used. We are, after all, a consuming society these days and I stepped off that track many years ago.
    As to the beans, I so agree. Rotate and use. If you are buying grain seeds like wheat, oats, etc. rotate too, and along the way, plant some of those seeds so you know how; if collapse should last longer than my 5-7 years, I want to be planting what I’ve stored for more food by then. When thinking long term, what happens when your ‘modern’ (sorry can’t think of another word right now) convenience stops working or runs out? I have lived in ‘modern’ places, only to have to move to more ‘primitive’ places where knowing how to live under almost any conditions helps these days.
    As to prepping, I am now, because I have obtained one of those flat iron hair straightners for which I am now creating my own spice blends for my health and for food preparations for those hard times. I’m labeling these and will also be rotating these, perhaps faster than I would other foods, but I’m using the chocolate chip mylar bags that aren’t costing me anything and saving since they aren’t going into the garbage either. In doing so, I am avoiding the chemicals which I don’t eat now either.
    I WILL however be buying some fd and dehydrated items which I just don’t have time to make but which I would miss greatly, like cheese and butter. ;) and other foods which cannot be grown locally but are keeping me healthier than if I didn’t have them, like pineapple. :)
    Even though I do things a bit differently, I am so appreciative of all I am learning through your website, keep it up. :)

  3. I’ve recently learned that while oxygen absorbers aren’t expensive, hand warmers are even cheaper and can be bought in lower quantities, eliminating the problem of securing leftover absorbers. So what do hand warmers have to do with food storage? They have the same ingredients and effect as absorbers when activated! Check it out!

  4. I’m curious about the 100 oxygen packs. If I’m packing something in a pint or quart mason jar, will 1 – 100 pack work or should I use more? What do you use for smaller quantities?

  5. This is great, Thank you so much for really explaining the how, why, and how much of the absorbers. I have been frequenting a handful of Prepper/Survival/Food Storage sites, and they all say to use them, but none have said how much or anything else.
    Love your site!!

  6. I don’t understand why sealing absorbers in a ziplock bag would be any worse than a Mason jar for storage. It would seem to me that there’s about the same amount of oxygen hanging out inside of both.

    • It is pretty difficult to get an airtight seal with a Ziploc. On the other hand, mason jars can be sealed so that they are impervious to oxygen and air in general.

  7. Also, you’ll be just fine putting absorbers in with seeds to preserve them. In fact, rendering them dormant by taking away oxygen is exactly what you’re trying to do. When you want to plant them, take them out and they’ll have access to oxygen again and have no problem germinating.

  8. a friend of mine gave me a candy boxes from Taiwan with “warm sachets” called O-Buster. I have no idea what it all about or why the manufacturer included such things. After consuming the candies I gather all this hot sachets and put it in the box with .45 Cal ammunition thinking it will ward-off moisture from the ammos. When I check it the next 2 or 3 days, the sachets hardened and not longer warm as it used to be. So I just put in trash bin for disposals.

    • putting the Oxygen absorbers in the ammo can is useless the way and manner you describe. Re-read the article, and I believe you will then understand. Good Ruck.

  9. Love your article. It is really informative and has loads of info I havent seen elsewhere! And yes I have looked! I love my straightening iron/ mylar sealer. This is its only use. I love that I can buy only one gallon size mylars and make my own smaller sizes with the iron. It works great!!! BTW, The pasta problem I have encountered only seems to be with the curly spiral types or the ones with holes through them like elbow and penne. They still seem to work… just take a lot longer sometimes.

  10. I read that you should not put an oxygen absorber in with sugar or salt. Can you tell me what other items that should not be stored using the oxygen absorber?

  11. As a Pharmacist for 35 years, I noticed almost every bottle of pills I opened had a “dessicant” packet it it. Since my retirement I have been becoming more self-reliant and self-sufficient. I ordered a bucket of dessicnat packs and included them in my Food Saver vacuumed sealed pinto bean bags (2 cups each bag) QUESTIONS: Will the desicant packs do the same as an O2 Absorber packet? will it hurt to put BOTH in a mason jar or vacuum-pack bag? I am new to this but now have the time and place to prepare for when SHTF. THANK YOU

  12. Here’s an “outside the box” question. I’m new at this but I’m reading that there’s a big hurry to use the oxygen absorbers once the package is open. I do some MIG welding and routinely use bottles of argon – a common inert gas. Since it’s heavier than air and is also used in the wine and home brew industries to flush oxygen out of barrels and bottles, what if you . . . 1) in an open garage out of the wind, 2) run a hose from a bottle of argon down into a 5 gallon bucket and turned the gas on very low, 3) put the un-opened bag of oxygen absorbers into the bottom of the bucket and opened it, 4) keep the absorbers in the 5 gal bucket, taking them out one at a time as needed, and when done, 5) put the remaining absorbers into a mason jar and seal it – doing it at the bottom of the inside of the bucket in the argon rich environment. Would this procedure not preserve the oxygen absorbers during the process and allow you to store the remaining ones in an argon rich environment inside the glass jar? Or am I over thinking this? Thanks!

    • JDS – Yes, definitely making too much work out of the process. Really, all you need to do is exercise some care and remove the O2 absorbers you will be needing in the next 10 minutes or so and put the rest back into a mason jar with the lid tightened. Rinse, lather, and repeat.

      It helps to prep your food in advance. Line up the filled Mylar bags, add the oxygen absorbers then seal them up in an assembly line process. Easy peasy.

  13. I really enjoyed the article and comments here. I have a question: Is it ok to use a 100cc oxygen absorber in a quart canning jar with dry rice or beans and then immediately use the Food/Game Saver vacuum machine with a regular or wide mouth lid attachment?

    I ask because on a survival forum I said that is what I was going to do and one poster said DO NOT use both because the oxygen absorber needs oxygen to activate it and work. I think it would be a good idea to use both as the vacuum machine doesn’t get all the oxygen out. What say you?

    • The oxygen absorber needs oxygen to work? Uh no, not quite. A better way of putting it is that the O2 absorber will activate itself when oxygen is present.

      Let me explain. When sealing a mason jar with a FoodSaver, you need to leave some headspace in the mason jar. Plus, food saver seals are not 100% perfect and over time may leak. The purpose of the oxygen absorber in the jar is to remove any residual oxygen, however small. Plus, the O2 absorber will pretty much guarantee that the seal holds.

      Try this for an experiment. Put some beans in a mason jar along with an O2 absorber. Seal the lid down with a standard mason jar ring. Come back in a day or two and the jar will be sealed without the use of a FoodSaver.

      The combination of the FS and the O2 absorber is simply a fail-safe. You KNOW the seal will hold and your food will stay fresh.

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