Long Term Secondary in Plastic Carboy??

I would not recommend a long term secondary in a ‘regular’ plastic carboy since it is not oxygen impermeable; the beer will get oxidized.

You could purchase a ‘special’ plastic carboy of Better Bottle carboy if you want to conduct a long term secondary in a plastic vessel. The plastic used to make Better Bottle resists oxygen diffusion across the material.

Cheers!

 

agree with Jack...but several factors to consider. For PET (Better Bottle), the oxygen diffusion rate is something like 1/10th that of HPDE (brew buckets). But that is not factoring in the width of the walls. Obviously HDPE that is say 20mm wide is about the same diffusion rate as PET that is 2mm wide:
http://www.faybutler.com/pdf_files/HowHoseMaterialsAffectGas3.pdf

 

There was a white paper on the Better Bottle website which listed the Oxygen Permeability Coefficients in units of cm3 mm/m3 day Atm 20° - 25°C for various materials. Below are the values for Better Bottle PET and HDPE

The Better Bottle PET had a value <1

HDPE had a value of 44—91.

Assuming a value of 1 for the Better Bottle PET it seems to me that this material has an oxygen diffusion rate of something like 0.022 to 0.011 that of HPDE (brew buckets). Needless to say but this is smaller than the 0.1 (1/10th) of the material you sourced.

I am not a Materials Engineer so I am not sufficiently educated to reconcile the various values and I do not know if and how material thickness plays into the overall discussion.

Cheers!

 

My understanding is that transmission rate and thickness are inversely proportional.

 

This may also be of interest to you.

http://www.mocon.com/pdf/optech/Closures - Oxygen Passage Study.pdf

 

As far as my experience go's, plastic buckets works grate for two month on secondary . The issue is not "off flavors" it's beer oxidized and long term light exposed.

 

Are you doing a sour? If not, I think it would be acceptable to put the beer on the chocolate and cherries for about a month and move on to packaging.