Gas/Water Permeability of Plastic Containers

[stormhawk]

Most of us here use the cheap disposable food-grade plastic containers to house everything from microworm cultures to even adult killies. I have always wondered as to how permeable are these containers to oxygen and CO2 exchange. Here's a website that I found which states the qualities of each type of commonly used plastics. From what I've read and learnt so far, I think the containers we use, which are usually made of polypropylene (PP) are permeable to oxygen and CO2. This means that I don't need to keep opening the containers every now and then to allow fresh air into the containers. Moisture loss is also at a minimum! :wink:

http://www.containerandpackaging.com...astic-comp.asp

[Ptarmigan]

http://www.containerandpackaging.com...astic-comp.asp

Thank you for posting that Jianyang, very interesting.
I also do homebrew beer and wine and the question of oxidation, moisture loss etc during bulk storage has importance in that hobby as well !

best wishes,
Malcolm.

[RonWill]

Jian Yang,

I did a check on all the containers in use and beneath every container, next to the 'recycling symbol', is stamped 05 (zero five) and PP (Polypropylene) but I'm maintaining too many cultures to reliably rely on permeability claims from the manufacturor.

IMHO, while it may be ok for a starter culture with few worms, the gaseous exchange is inadequate for the needs of a thriving culture.

That said, to minimize culture crashing due to suffocation and to reduce the 'breathing sessions' (ie. opening the cultures' lids), I've taken to making 'breathing windows' and applying a thin film of breathable material to seal this window from mites and ants.

The 2-week trial with 3M's 'Micropore' surgical tape and Smith+Nephew's 'Opsite Flexigrid' has been encouraging and I may convert or add windows, to all my current culture containers. YMMV, of course.

BTW, Malcolm, I'm glad you're still with us (will catch up with you on the home brew... I'm toying with the idea of buying a Coopers Micro Brew Kit and yes, I prefer a darker brew :wink: ).

[Ptarmigan]

BTW, Malcolm, I'm glad you're still with us (will catch up with you on the home brew... I'm toying with the idea of buying a Coopers Micro Brew Kit and yes, I prefer a darker brew :wink: ).

Hi Ron, yep, I'm still lurking :-)
I didnt reply to this earlier cos homebrew is a wee tiny bit OT so I waited a while to see if KL would be adding a chat/natter/relaxing-room to the site (as earlier discussed) in amongst the changes that he is contemplating.
Briefly, and for anyone else contemplating homebrew -
I have not used that particular kit from Coopers ( I am not fond of lager - my tipple is beer) , but I have used other Coopers stuff and have been well pleased with the results. So I wish you good luck etc. At the rate at which our government taxes our booze over here it is an enterprise well worth the effort for us ( no tax on homebrew ! only on the commercial beers and wines)
By the way, guess who has 3 hop plants growing in his garden :-)))

Cheers,
Malcolm.