"Oxygen transmissiblity of Plastic"

Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum

Help Support Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

casebrew

Well-Known Member
Joined
Dec 11, 2005
Messages
856
Reaction score
8
Location
San Diego
Here's an intreresting link I found : <shttp://www.alphap.com/basics/compare.html>

With an interesting chart.

Check the right hand column, "recycle numbers". The O2 column is oxygen transmisiliby, lower is better.

Some stuff I noticed: #7 bottles pass only 1/2 as much as #1 bottles. So #7 is TWICE AS GOOD FOR BEER, as far as staling goes. #2, as in bucket fermenters, pass 53 times as much oxygen as a #1 bottle. So #7 plastic would be 100 times better than a plastic bucket. I'll repeat that:

#7 PLASTIC IS BETTER THAN #1 PLASTIC.

#7 PLASTIC IS 100 TIMES BETTER THAN A PLASTIC BUCKET.

So, if a plastic #2 bucket is just fine, then it just don't matter, does it?


Note also the CO2 transmissability column, that each of those plastics pass CO2 at 4 to 7 times the speed of oxygen. SO:

YOUR BEER WILL GO FLAT, BEFORE IT GOES STALE, IN ANY KIND OF PLASTIC.

I did some googling on the #1 carboys. All the sales literature seems to compare them to glass. Nothing to compare them to the mass market water jugs. No "Our jugs are better than #7 jugs because ______"
 
Don't forget to take thickness into account. Does O2 permeability decrease linearly or exponentially with an increase in thickness?

I don't know the answer to that, but I know enough to ask the question...
 
Here's the problem.

Recycle Code 7 means "other" plastic.

Plastic ID Code "7" is for the other plastics except above mentioned 6 groups.

Source: http://www.kenplas.com/topic/recyclelogo/

Alternatively,

Properties: varies according to constituent resins
Statistic: In 1999 there was minimal usage of resins in the 'other' category in plastic bottles.


Description: The category of "Other" includes any resin not specifically numbered 1, 2, 3, 4, 5, or 6, or combinations of one or more of these resins.

Packaging applications: Three and five gallon water bottles, certain food product bottles

Recycled products: Plastic lumber, custom-made products

Source: http://www.earthodyssey.com/symbols.html

Now, your website states that Polylactide is Recycle Code 7 - that DOES NOT mean that all Recycle Code 7 is Polylactide. It simply means that Polylactide is not one of the other six that can be recycled.

So, if you buy a bottle that is Code 7, it COULD be Polylactide; if it is, you're in luck.

It also could be pretty much anything else, which would put you SOL.
 
Very interesting since #7 is listed as "Other" how would you know that you are getting PLA plastic or something else?

Maybe it is I don't know.
 
Well, you'd order PLA plastic from your manufacturer---- the recycle code isn't there to help you spec out your purchase, really. It's there to aid in recycling efforts.
 
I guess all those guy brewing in #7 have been just flat out lucky then? All of them?

Anybody got some examples of water bottles labeled #7, that are known to be somthing other than Polylactide? Anybody? Beuller?

But again, anydamn stuff is better than the ubiquitous #2 bucket.
 
I'm just happy that better bottles and fermentation buckets are 100% recyclable.

<-- Tree hugger
 
casebrew said:
But again, anydamn stuff is better than the ubiquitous #2 bucket.

Meh, the bucket seems to work fine for a primary. If it ain't broke, don't fix it and all that...
 
casebrew said:
I guess all those guy brewing in #7 have been just flat out lucky then? All of them?

Anybody got some examples of water bottles labeled #7, that are known to be somthing other than Polylactide? Anybody? Beuller?

But again, anydamn stuff is better than the ubiquitous #2 bucket.

I've aged two in plastic bottles and I didn't particularly care for either batch. I'm not 100% sure it's due to the bottle but evidence points. I'm doing a final test where I split my melomel into two vessels (out of necessity). I'll post the differences.
 
*MVTR stands for Moisture Vapor Transmission Rate in g-mil/100in. 2/24hr. MVTR is a measure of the passage of gaseous H2O through a barrier. The lower the rate, the longer the package protects its contents from moisture and ensures the moisture content of the product remains the same.

#1: 2.0
#7: 18-22
 
So are you staying that the nubmers mean exactly the opposite of what the original poster said?
 
Let's not forget the flavor scalping associated with other types of plastic. Flavor scalping that does not occur with PET plastic. Other types of plastic use plasticizers in the manufacture, PET does not. PET or polyethylene terephthalate, is made by polymerizing tere-phthalate with ethylene glycol. It also will not absorb any odors or flavors from the products in them so there is no chance of passing any odors or flavors from batch to batch. The same cannot be said of other plastics. Even food grade HDPE #2 (high density polyethylene).
 
johnsma22 said:
Let's not forget the flavor scalping associated with other types of plastic. Flavor scalping that does not occur with PET plastic. Other types of plastic use plasticizers in the manufacture, PET does not. PET or polyethylene terephthalate, is made by polymerizing tere-phthalate with ethylene glycol. It also will not absorb any odors or flavors from the products in them so there is no chance of passing any odors or flavors from batch to batch. The same cannot be said of other plastics. Even food grade HDPE #2 (high density polyethylene).

Do you think bottled water companies want their water to pick up flavors in the fridge?
 
Do you think the bottled water companies really care if the water you buy from them picks up flavors? They don't if they are bottling their water in #7 plastic carboys!
 
Cheesefood said:
*MVTR stands for Moisture Vapor Transmission Rate in g-mil/100in. 2/24hr. MVTR is a measure of the passage of gaseous H2O through a barrier. The lower the rate, the longer the package protects its contents from moisture and ensures the moisture content of the product remains the same.

#1: 2.0
#7: 18-22

So, you'll lose 10 times as much to evaporation? Anybody here ever been concerned with evaporation from a fermenter before? Anybody ever measure/ calculate vapor, um, plus or minus?

Oh, That's water vapor, not liquid.
 
casebrew said:
So, you'll lose 10 times as much to evaporation? Anybody here ever been concerned with evaporation from a fermenter before? Anybody ever measure/ calculate vapor, um, plus or minus?

Oh, That's water vapor, not liquid.

No, you're letting in 10 times more humidty.
 
johnsma22 said:
Let's not forget the flavor scalping associated with other types of plastic. Flavor scalping that does not occur with PET plastic. Other types of plastic use plasticizers in the manufacture, PET does not. PET or polyethylene terephthalate, is made by polymerizing tere-phthalate with ethylene glycol. It also will not absorb any odors or flavors from the products in them so there is no chance of passing any odors or flavors from batch to batch. The same cannot be said of other plastics. Even food grade HDPE #2 (high density polyethylene).

Any Evidence that polylactide is not as good as PET? As I tried to point out, bottled water companies would not use a bottle that picks up flavor from the einvironment- like onions in your fridge.

Anybody have any direct experience? I sure have a water jug that was made to fit in a fridge- #7.
 
Cheesefood said:
I've aged two in plastic bottles and I didn't particularly care for either batch. I'm not 100% sure it's due to the bottle but evidence points. I'm doing a final test where I split my melomel into two vessels (out of necessity). I'll post the differences.

Did you mean #7 water jugs, or "better bottles" ?

What probelms? Too much evaporation? Flavor scalping? Until I came along, the only problem ever mentioned was oxygen transmission, leading to stalenesss, the wet cardboard taste.
 
You're still working under a bad assumption.

Where do you see ANY evidence that the plastic water cooler bottles are polylactide? The fact that polylactide is #7 does NOT mean that all #7s are polylactide. Unless you can establish that the water cooler bottles are, in fact, made of polylactide (using some form of evidence other than their recycle number), there's no argument here.
 
the_bird said:
You're still working under a bad assumption.

Where do you see ANY evidence that the plastic water cooler bottles are polylactide? The fact that polylactide is #7 does NOT mean that all #7s are polylactide. Unless you can establish that the water cooler bottles are, in fact, made of polylactide (using some form of evidence other than their recycle number), there's no argument here.

There has also been absolutely no evidence presented that fermenting in a #7 water jug has ever done any harm to anybody's beer. Only the theory that it may be more oxygen pemeable. It just ain't necessarily so.

That was not the first site I visited while looking into this. I learned that #7's can be plastics used in combinations. Like bitchen stuff that has an extra treatment to the inside to prevent some pertinent problems. I.E., #7 bottles could be PET, with a nitrogen gas treatment to make them even better.
 
Another hour of googling has found me very little pertinant data.

Just that the <7> plus PC under the triangle means Poly Carbonate. Have I seen <7> PLA bottles? They would be awesome fermenters. And i don't see anything wrong with PC either. And you know the bottler thought it was good enough for consumer water, whatever the resin.

PLA is not very recyclable, yet, but is supposed to be compostible.

It's PVC containers that have the loads of plasticisers- mostly shrink wrap.

PET can leach antimony into it's contents. Other plastics leach other stuff, in parts per BILLION. I think PET does too.

I just looked at every plastic container in my house. All have the number, plus under the number, the initials for that type of resin. Only one #7, under the <7> said 'other'. No help there.
 
I just spent the last hour of my life compiling the info to make the case for PET over other types of plastic, and then I realized..... I don't give a ****! Ferment in a fuc@ing old shoe if you prefer!
 
agh. I've posted this half a dozen times in this forum in the last year or more.

#7 blue water cooler bottles are a POLYCARBONATE COMPOSITE. The SAME stuff Nalgene bottles are made of, all be it thinner.

So more O2 permisible than PETE but still not bad. And to be honest you will lose CO2 before you will see O2 permeate.
 
johnsma22 said:
I just spent the last hour of my life compiling the info to make the case for PET over other types of plastic, and then I realized..... I don't give a ****! Ferment in a fuc@ing old shoe if you prefer!

:D :D Just for arguments sake should that be an old nike or old reebok :D :D .

This thread is like a return to aristotlean logic what with the whole all #7 are this but not all # are that, 'you, you are number six, i am not a number i am a FREE MAN'

What about some emperical science here has anyone had beer gone stale in these containers or tasted flavour transfer ie onions in the fridge to the liquid in the bottle.
 
I use better bottles, I already have them, sunk cost, so I don't really care either way. However, I would suggest that there are probably 20 other factors in your brewing process that would affect the flavor of a batch moreso than any difference in fermenter makeup (unless we're talking about something highly porous like wood or unglazed ceramic). If buckets are marginally acceptable, I'm sure you'll be fine with your #7 water jug.

What I'm trying to figure out is what your goal is. Are you looking to convince everyone to stop wasting money on PET bottles?
 
Oooo---- homebrew geek fight!

*streaks across room*

ALUMINUM POTS SANITIZED WITH BLEACH SO YOU CAN MAKE CORONA IN YOUR PARENTS' BASEMENT IS TEH AWESOME!






*stops to poke a pile of pooh with a stick*
 
Anybody got a PLA carboy, Or know where I can get one.
I'll be happy to run an experiment.
 
clayof2day said:
My question: Whats the OTR for glass?


I didn't look for it, but it's probably pretty low.

I did look for OTR of polycarbonate, but couldn't find any info. Except to say that it is used for lots of food stuffs. And to make oxygen permeable contact lenses. So probably OK for food as far as emitting chemicals.

I've looked at a couple more 5g bottles, found some labeled PC, most labeled 'other', none PLA.
 
Bobby_M said:
I use better bottles, I already have them, sunk cost, so I don't really care either way. However, I would suggest that there are probably 20 other factors in your brewing process that would affect the flavor of a batch moreso than any difference in fermenter makeup (unless we're talking about something highly porous like wood or unglazed ceramic). If buckets are marginally acceptable, I'm sure you'll be fine with your #7 water jug.

I don't think buckets are "marginally acceptable", I think they are the standard of the homebrew industry. The upgrade to glass or Better Bottles is NOT sold for chemical reasons, but for esthetic purposes. PC is better than the buckets, but the myth is that they are the worst thing you can do short of peeing into your beer.


Bobby_M said:
What I'm trying to figure out is what your goal is. Are you looking to convince everyone to stop wasting money on PET bottles?

No. Spend YOUR money however you like. My goal is to demystify homebrewing for the noobies. Making the hobby seem more technical (and more expensive) than it has to be scares folks away. Maybe I'm tilting at windmills. Oh well.

Keep in mind that the responses here are from the Choir member. Many devotees are lurkers, usually about 10 to each choir member. So forum discussions are educating more parishoners than you may realize.

All of these myths seem to make life more difficult for the noobs, and are FALSE:

Aluminum pots are bad. (Totally false)

Sucrose is bad. (partially false. Generally 20% is acceptable, but it's the lack of nitrogen that causes the off taste. Refined extract is as much the culprit as too much sucrose, which is glucose and fructose, without which you wouldn't have beer)

AG costs will send you to the poorhouse (if you believe all these myths)

Lead in brass fittings is bad. (How many cases of lead poisoning are reportedly due to lead in water lines?)

You have to mash in an insulated MLT. With $40 worth of fittings.

$1 worth of chlorine? NOoo, you need $16 worth of _____!

"Food Grade" anydamnthing.

Oxygenate, or else.

Lager is better than Ale.

Ale is bettter than Lager.

Keggers are better than bottlers.

Beer should taste like grapefruit peels. ( I'm a malt head, and just thought I would throw that in)

In the words of one of our heroes: " Just Brew It!" And try to be supportive to those disadvantaged members of the group who have lesser knowledge. Like me?
 
I have been using a water bottle with a #7 in it for a while and it makes good beer. Dont knock it Unless you have tried it.
 
casebrew said:
I don't think buckets are "marginally acceptable", I think they are the standard of the homebrew industry. The upgrade to glass or Better Bottles is NOT sold for chemical reasons, but for esthetic purposes. PC is better than the buckets, but the myth is that they are the worst thing you can do short of peeing into your beer.




No. Spend YOUR money however you like. My goal is to demystify homebrewing for the noobies. Making the hobby seem more technical (and more expensive) than it has to be scares folks away. Maybe I'm tilting at windmills. Oh well.

Keep in mind that the responses here are from the Choir member. Many devotees are lurkers, usually about 10 to each choir member. So forum discussions are educating more parishoners than you may realize.

All of these myths seem to make life more difficult for the noobs, and are FALSE:

Aluminum pots are bad. (Totally false)

Sucrose is bad. (partially false. Generally 20% is acceptable, but it's the lack of nitrogen that causes the off taste. Refined extract is as much the culprit as too much sucrose, which is glucose and fructose, without which you wouldn't have beer)

AG costs will send you to the poorhouse (if you believe all these myths)

Lead in brass fittings is bad. (How many cases of lead poisoning are reportedly due to lead in water lines?)

You have to mash in an insulated MLT. With $40 worth of fittings.

$1 worth of chlorine? NOoo, you need $16 worth of _____!

"Food Grade" anydamnthing.

Oxygenate, or else.

Lager is better than Ale.

Ale is bettter than Lager.

Keggers are better than bottlers.

Beer should taste like grapefruit peels. ( I'm a malt head, and just thought I would throw that in)

In the words of one of our heroes: " Just Brew It!" And try to be supportive to those disadvantaged members of the group who have lesser knowledge. Like me?

Great post :cool:
 
Crabmeat said:

Now that is cool! Would a more classic shape settle the trub better- drain often, shake a bit form time to time to get the settled gunk off the 'shoulder'?

How is the leakage at the mouth?

It's disposable, when you make the next one you can us the old one to make a stand? Cut it in half, cut a valve access hole in the side, set the new one on, stand by for fermentation!
 
haven't used it yet, I plan to use it for my first all grain. No leak on the inside, peer close and you can see a 7/16 o-ring. As for the trub that will settle below the opening of the pvc on the inside, I plan on using the cap from a juicy juice bottle to block trub from settling below the pvc because it fits perfect in the neck. I just need to drill a hole in the juicy juice and kill a bottle off.
 
Crabmeat said:
haven't used it yet, I plan to use it for my first all grain. No leak on the inside, peer close and you can see a 7/16 o-ring. As for the trub that will settle below the opening of the pvc on the inside, I plan on using the cap from a juicy juice bottle to block trub from settling below the pvc because it fits perfect in the neck. I just need to drill a hole in the juicy juice and kill a bottle off.

I wouldn't worry about that. The small surface area of the trub in the neck won't hurt. Especially when you will still get a small build up on your juice cap. Perhaps conicals don't even need to be drained of trub? The cone shape reduces the suface area of the trub that is exposed to the beer. But OH, you still need to get the beer out...

Did you make your hole in for the bubbler big enough to take hydrometer samples? And/Or a blow-off tube?
 
Ideally all of the trub would come out with minimal wort loss.

What can happen with this design is this is that when you try to rack off the trub, the pressure punches a hole in the trub, so alot of it remains in the carboy.

This can happen with SS conicals. I think that people hit the outside of the SS conical with a rubber mallet to ensure the trub gets racked.

Please let us know the outcome.
 
Back
Top