Plastic or Glass

Question

Plastic or Glass fermentors? (Lets keep stainless steel out of this debate for now) Each has ups and downs.

What are the main differences for the following aspects:

• Shapes and configurations
• Heat transfer and stability
• Oxygen permeability
• Weight
• Clarity
• Ease of cleaning
• Resistance to cleaning method/products
• Popularity
• BEER QUALITY!!!

Answer 1

Shapes and Sizes:
Buckets and Carboys for Glass is available. You can also get plastic conical type fermentors. For total variety, plastic wins here.
Heat Transfer and Stability:
Glass is slightly quicker to give up and take heat than a plastic walled vessle. However, glass doesn't always like rapid changes in temperature and can break as a result. Depending on the thickness of the plastic being used, heat stability would likely be higher in plastic.
Oxygen Permeability:
Glass has zero pass through of O2. Most plastic food grade HDPE buckets do allow some O2 transfer. The better bottle which is PET has a much lower rating to O2 transfer across the wall however. But how much is too much still leaves this question unanswered I think. With most primary ferments being 3 weeks or less, its probably a non-issue. However if you wanted to do a year long primary for something like a Flanders or a lambic... Glass would be your best choice here.
Weight:
Platic wins here when comparing vessels volume against volume usually.
Clarity:
Non-colored glass is probably superior to even the Better Bottle. But all things being equal, this is a tie likely.
Ease of Cleaning: For physically cleaning it out with your hands, I haven't seen to many glass buckets around, so plastic buckets win out here.
Resistance to cleaning method/products: Even though you can reach into a bucket and scrape it out with a chisle if you so desire, its not recommended to scratch up plastic. And it will scratch easily. So if yo were going to use a normal cleaner like PBW the two materials probablt tie. But if you wanted to used some sort of professional grade caustic... glass would win depending on its concentration. At least glass eliminates the worries of plasticizers leaching out of the bucket during a good soak with said cleaner.
Popularity:
Likely a tie here too. Many starting brewers use buckets and make great beer for a long time. I haven't seen any hard data that mentions how many people switch to glass carboys, but I think the better bottle has stolen some of those stats back to plastic.
Beer Quality: In the end isn't this all that matters. The only comment I have here is that when the AHA posts its National Homebrew Competition winners they often have fermentor type listed in with the winning recipes. I have never seen someone say they used plastic. Either they don't want to admit it or year after year people win in part because of glass (that's a big leap in assumptions though.) This may speak to popularity.

Here is a short piece from my blog on this topic: Plastic or Glass for Competition

Answer 2

An as-of-yet unmentioned pro for plastic, when used in bucket form, is that it has a standard bucket handle which really helps when transporting a full fermenter. To safely transport a full carboy (glass or plastic), you need to attach something like a Brew Hauler.

An as-of-yet unmentioned con against plastic buckets is that removing the lid can be very difficult. I always had to fight with it, and I'm not the tiniest guy. It could be nearly impossible for some people. Removing the rubber stopper from a carboy takes little effort. They do make bucket lid removers, though. One more thing to buy.

I use carboys because:

• The rubber gasket in the airlock hole in the lid of my bucket dry-rotted. I had to replace the bucket lid. That's $3. Then I noticed that my bucket had become quite scratched because I stored my other gear in it. It was due to be replaced. Another $11. So I decided to spend $30 instead of $14 for what seemed like a step upward.
• My bucket always smelled funky due to the plastic's absorbing the smell of fermenting beer.
• I really like being able to see what's happening in the fermeneter. I still love seeing the krausen and watching the yeast chunks swirl around during the most active days of primary fermentation. That's an intangible benefit for me. A better bottle would meet this criterion.

NOTE: PJ - you can replace the Amazon links with this site's Amazon referral links and remove this note.

Answer 3

For ease of cleaning, glass wins since it isn't easily scratched, and will withstand harsher cleaning methods over time. Also, plastic will have to be replaced periodically as it can get stained and / or leach over time.

Plastic isn't nearly as fragile or heavy as glass, so it wins on those fronts. It's much less expensive than glass, which is why so many brewers start with plastic. It's also much more versatile, and can be used both for fermentation, as a cleaning bucket, a bottling bucket and for storing all your kit in between brewing.

Both work fine for basic fermentation without effect on the finished quality of the beer. What's more important is sanitation of the fermenter, not whether it's plastic or glass (unless you are aging, which you should never do in plastic).

We've only just begun selling Better Bottles at our shop, so don't have any customer feedback on how well they hold up over time.