Oxygen Permeability of #5 PP (polypropylene)

[blazie151]

I've searched around and seen the differences between PET, multi-layer PET, HDPE, LDPE, and glass, but found almost nothing about the oxygen permeability of PP (polypropylene). I'm planning on aging a couple gallons of my current brew for around 8 months or so and am looking at what type of container I can use. I was originally going to use PET 2l bottles, thinking that since recipes like Apfelwine are aged for months in better bottles (PET plastic) it'd be fine, but now I'm convinced that the thickness of better bottles is a multi-layer PET with some other plastic providing the oxygen barrier and 2l bottles would end up leaving the brew oxidized and ruined. So I looked into HDPE and read that people are having issues with oxygenation after only a couple months. Now I'm looking into polypropylene, but can't find any good data on it. I ask about these because I get these buckets for free and would prefer to use them over spending money on better bottles I'll almost never use. All my brew buckets are HDPE or PP, cheap or free, and most importantly, stackable. I'd like any bulk aging containers to share some of those characteristics. FYI, I'm not concerned with bottle carbing at all, so pressure requirements are null.

 

[alien]

For oxygen permeability

PET << HDPE < PP

PET is the best of these by a factor of 10.

 

[blazie151]

That was the most useful reply you could have ever posted. Thank you very much! That shows the exact data I needed and couldn't find, and for every common plastic on the market. I'm surprised some people are having issues aging in single layer PET due to oxygenation. I wonder if covering PET bottles in a layer of Saran would help, since it's oxygen barrier is the best on that list.

 

[sablesurfer]

LOL...saran wraping your plastic fermentors...very interesting. I found this thread looking for info on LDPE as a primary. Anyone have a thought on those permability numbers and how long is safe? Hmmm.

 

[alien]

For primary I would guess it doesn't matter much - it's in not there long enough.

 

[dlester]

blazie151, You may be relying on comments about permeability problems that are not data related. Some people don't know how to properly transfer wort and may have aerated the wort prior to, or during transfer. For instance, I use C02 as a barrier that would solve aeration problems during transfer. That said, I would be interested to see the results after the long term storage using PP & PET as containers. Even if it is a small one if your unsure of the results.


Cheers,