I have 15 gallon plastic drums, like what LME comes in. I would really like to use them to age my sours in but I'm concerned with O2 permeability. Has anyone tried this or have any good resources on types of plastic/permeability...
According to the guys at this sour-only brewery they use only glass, stainless or wood. Plastic lets in too much oxygen, leading to acetic acid.
Also, the shape of a barrel allows them to eliminate the air space above the beer by topping up periodically with fermented beer.
BTW that link is a 3-1/2 hour podcast, but I'm 95% confident the content is in there somewhere.