UncleDave

Recipes 

The reason I ask is if it is so important, why aren't primary fermentation/bottling buckets also made out of the material? Seems like it would be counterproductive to primary for two weeks in a food grade poly bucket and then transfer to a PET bottle for secondary. I wonder if PET is really a better material for use as a fermentation vessel or if this is a way to market a higher priced item to homebrewers?

david_42

Recipes 

PET bottles are mainly used as fermenters, because they don't want to use buckets and are concerned about glass breakage. I doubt many people use PET bottles for exclusively clearing.

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jkpq45

Recipes 

PET's cool 'cause it's clear/transparent. As long as you're food safe and your polymer isn't leaching chemicals (meaning it's made of #1 or #2 polymer) you'll be golden.

Or so says the HBT research I've been doing concerning polymer-type fermenters....

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Cpt_Kirks

Recipes 

Better Bottles are a big reason I returned to homebrewing after a 15 year hiatus. If you have ever had the bottom of a glass carboy full of wort come off you would know why.

I LOVE me some Better Bottles!!!

MSUConrad

Recipes 

I have 12 glass carboys (love Craigslist) and one better bottle. I never use the better bottle. The first time I picked it up, I guess I accidentially squeezed it. And then when I set it down, all of the sanitizer in the airlock sucked into the carboy.

I'm super-over careful with the glass ones becuase they can certainly become a danger, but I feel they are superior when handled correctly.

CBBaron

Recipes 

During primary the yeast are active using O2 if available and out gassing CO2. This prevents and oxidation problem.
During long term aging the beer will oxidize if exposed to much O2, which will lead to off flavors.
PET is nearly impermeable to O2 while food grade buckets are quite permeable.

So PET is good for long term storage of a stable beer or wine. It can be used for primary if you prefer to visually see the beer, and have a material less scratch prone but it is not necessary during active fermentation.

So O2 permeability is the main reason for using PET or glass over food grade buckets. For comparisons of PET and glass see the many threads on that subject

Craig

UncleDave

Recipes 

Thanks everyone. I do find the outgassing of CO2 explanation to be compelling. Not trying to do another PET vs. glass debate, but rather PET vs. poly. I wonder which would introduce more oxidation into a batch... keeping it in a poly bucket for 4-8 weeks or transferring into a PET secondary vessel for aging/conditioning.

Cpt_Kirks

Recipes 

Poly buckets are fine for use as primaries and for beers that finish quick.

I often use an ale pail for wheat beers.