# See-through mylar bags and damp oxygen absorbers



## markbriscoe (11 mo ago)

Hi, this is my first post here.
I recently bought some mylar bags on eBay Aluminum Foil Mylar Sliver Food Storage Pouches Package Heat Seal Vacuum Bags | eBay
They are a very shiny silver colour but seem to be fairly see-through. Such that I can even see the bedroom window through both layers of plastic, is that normal? i would've thought aluminium would be completely opaque (perhaps not if its extremely thin?)
The title on eBay is "Aluminum Foil Mylar Sliver Food Storage Pouches Package Heat Seal Vacuum Bags"
Not sure if these are good or not. 

Another question is that I also bought some oxygen absorbers, I opened the plastic bag in which they were contained and the next day the bag had wet droplets on the inside as if the absorbers had been steaming off moisture. I transferred the absorbers to a glass jar and left it open on an oven plate at a very low setting to force dry the absorbers. Is this ok or have they been ruined by moisture? Thanks


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## Back Pack Hack (Sep 15, 2016)

Shipped from China.... = Do Not Use.

As for the O2 absorbers, did you _completely _seal them back up? If not, they're toast now.


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## Kauboy (May 12, 2014)

Without physically inspecting the bags, I can make no comment.

Your absorbers are done. If you opened the bag and did not reseal it completely, they continued to react with O2, generated heat, produced condensate inside the bag as a result, and stopped reacting when all iron had been converted.
There is no way to undo this process. They do not function like silica moisture absorbing packets, which can often be dried and reused. Once the iron filings have reacted with O2, they are useless.


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## paraquack (Mar 1, 2013)

For what it's worth. I just checked my bags, holding them up to the sun. Yes, I can just barely see the sun thru one layer. Just the sun, nothing else. The purpose of the aluminized coating is the prevent ultraviolet light from getting in. Unless you plan on leaving your food out in direct sunlight, it should be fine. 
BTW, oxygen aborbers only last unused and unopened for maybe a year. I always try to use all absorbers in the package in one sitting. I put any unused absorbers in the smallest possible canning jar and vacuum pack it to keep the air from getting inside. Might last 6 months.


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## markbriscoe (11 mo ago)

thanks for all your answers... yes, after heating the open jar containing the absorbers I put a lid on. but opinion seems to suggest they are done for  regarding the bags, i guess i will just have to see how they perform (over a ten year period ) ... I wonder how long the (lentils and chick peas) will last with falty (but dry) absorbers in the bag?


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## Back Pack Hack (Sep 15, 2016)

I'd be scared shítless using no-name food storage from China. Food is such an essential commodity (much like water) one doesn't want to cut corners. I prefer not ingesting gobs of unknown chemicals.

Yes, I get the notion that not everyone has a truckload of spare money, but there are some things one simply does not cheap out on.


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## FloridaScamp (Dec 23, 2021)

markbriscoe said:


> Hi, this is my first post here.
> I recently bought some mylar bags on eBay Aluminum Foil Mylar Sliver Food Storage Pouches Package Heat Seal Vacuum Bags | eBay
> They are a very shiny silver colour but seem to be fairly see-through. Such that I can even see the bedroom window through both layers of plastic, is that normal? i would've thought aluminium would be completely opaque (perhaps not if its extremely thin?)
> The title on eBay is "Aluminum Foil Mylar Sliver Food Storage Pouches Package Heat Seal Vacuum Bags"
> ...


That is not normal, I started freeze drying a few months ago and the best advice, get 7ml mylar bags, yes they cost a few cents more but it beats losing the food that your trying to hold because of faulty bag.

I used topmylar.com


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## markbriscoe (11 mo ago)

Thanks for more feedback... I have ordered some 'shield pro' 2 gallon mylar bags that would seem to be legit. 
can anyone give me a rough estimate of how long you can store items in a vaccumed heat sealed mylar bag WITHOUT an oxygen absorber (since the absorbers i have are probably dud) 
for example I have vaccum sealed some lentils that have a sell-by date of Feb 2023. How far beyond that date, roughly, would they be ok? 

are there any storage charts around that list how long you can store (in vaccumed mylar bags) various food items such as dried milk powder, rice, pasta, lentils, dried chicken,


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## Kauboy (May 12, 2014)

markbriscoe said:


> how long you can store items in a vaccumed heat sealed mylar bag WITHOUT an oxygen absorber


If it's vacuum sealed, meaning all air has been removed from inside the bag before it was sealed, O2 absorbers would be redundant and unnecessary.
O2 absorbers are used when you are not able to vacuum out the air.
If you're able to vacuum seal your bags, there's no oxygen inside to decay the food. Many dry foods can last 20+ years in such a state.


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## Back Pack Hack (Sep 15, 2016)

Kauboy said:


> If it's vacuum sealed, meaning all air has been removed from inside the bag before it was sealed, O2 absorbers would be redundant and unnecessary.
> O2 absorbers are used when you are not able to vacuum out the air.
> If you're able to vacuum seal your bags, there's no oxygen inside to decay the food. Many dry foods can last 20+ years in such a state.


Vac-sealers DO NOT remove ALL the air. They simply remove SOME of it. If one managed to actually remove all the gas in a mylar bag, the surrounding air pressure would crush the contents.

Unless you have access to lab-grade vacuum systems, you'll still need O2 absorbers.


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## Kauboy (May 12, 2014)

Back Pack Hack said:


> Vac-sealers DO NOT remove ALL the air. They simply remove SOME of it. If one managed to actually remove all the gas in a mylar bag, the surrounding air pressure would crush the contents.
> 
> Unless you have access to lab-grade vacuum systems, you'll still need O2 absorbers.


I did mention that vacuum would mean removing all air. If the vacuum sealer being used doesn't do that, then it isn't what I was referring to.
If using a device that reduces the air volume, but doesn't create a vacuum, you're just wasting time and making a slightly smaller package.
If planing to use O2 absorbers, don't bother with vacuuming anything. Squeeze the air out by hand, toss in the appropriate number of O2 absorbers, and seal.


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## Back Pack Hack (Sep 15, 2016)

Kauboy said:


> I did mention that vacuum would mean removing all air. If the vacuum sealer being used doesn't do that, then it isn't what I was referring to.
> If using a device that reduces the air volume, but doesn't create a vacuum, you're just wasting time and making a slightly smaller package.
> If planing to use O2 absorbers, don't bother with vacuuming anything. Squeeze the air out by hand, toss in the appropriate number of O2 absorbers, and seal.


"Vacuum" sealer is a marketing term.

Does your vacuum cleaner create a vacuum in your living room when you run it?


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## Kauboy (May 12, 2014)

Back Pack Hack said:


> "Vacuum" sealer is a marketing term.
> 
> Does your vacuum cleaner create a vacuum in your living room when you run it?


Indeed it is, but I didn't refer to a vacuum sealer. Just to a vacuum. 
If you can't create a vacuum within your storage container, it's a waste of energy and time. Just use O2 absorbers.


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## Back Pack Hack (Sep 15, 2016)

So.... having less oxygen in a package still means one needs to use the same size O2 absorber as if there were 'normal' amount of oxygen in the package?


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## Kauboy (May 12, 2014)

Back Pack Hack said:


> So.... having less oxygen in a package still means one needs to use the same size O2 absorber as if there were 'normal' amount of oxygen in the package?





Kauboy said:


> ...toss in the appropriate number of O2 absorbers...


Use what's needed. If the pennies that an extra sachet costs is going to break you, it's probably not best to buy an expensive device marketed as a "vacuum" sealer.


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## Back Pack Hack (Sep 15, 2016)

No thanks. I'll continue to use what works. A vac-sealer with O2 absorbers. The pennies aren't going to break me.... now that you've moved the goal posts to the economy end of the field.


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## Kauboy (May 12, 2014)

Back Pack Hack said:


> No thanks. I'll continue to use what works. A vac-sealer with O2 absorbers. The pennies aren't going to break me.... now that you've moved the goal posts to the economy end of the field.


You brought up using more than needed, not me.


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## markbriscoe (11 mo ago)

Just a quick update... I recently bought a NEW pack of O2 absorbers ... I opened the sealed pack today and immediately transferred some of them to a glass jar and re-vacuum sealed the bag. The jar was fully dry and warmed before adding them. within 3 - 4 hours the jar has a lot of water condensation on the inside. previously I left the absorbers open overnight (so my fault) but this time are the absorbers faulty?


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## Kauboy (May 12, 2014)

markbriscoe said:


> Just a quick update... I recently bought a NEW pack of O2 absorbers ... I opened the sealed pack today and immediately transferred some of them to a glass jar and re-vacuum sealed the bag. The jar was fully dry and warmed before adding them. within 3 - 4 hours the jar has a lot of water condensation on the inside. previously I left the absorbers open overnight (so my fault) but this time are the absorbers faulty?


The absorbers produce heat when the iron and O2 combine. This will cause condensation on the warmer side of the jar wall. Like the condensation that forms on the warmer outside of your cold beverage glass. The absorbers were working. Depending on the jar seal, they may now be used up. The ones you resealed in mylar could still be good, if well sealed.

Honestly, I've been very impressed with the results I'm getting with hand warmers, and they come individually sealed. Lower risk/worry about wasting more than needed.


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