Unless you’re one of the lucky few who have the extra cash and space for a stainless steel cylindroconical fermentor, chances are you ferment your homebrew in glass or plastic. The debate over which is better is as old as the hobby itself, and you’ll find loyalists on both sides of the divide. As with most things, choosing one over the other is largely a matter of personal preference, but here are a few things to keep in mind.
Glass
A 6.5-gallon glass carboy is the time-honored fermentation vessel of choice, while 5-gallon carboys are favored for aging. Glass is rivaled only by stainless steel for ease of sanitation and, with proper care, a glass vessel can last a lifetime.
Pros
- Glass is impermeable to oxygen.
- Glass doesn’t readily scratch and is therefore less prone to contamination than plastic.
- Tough surface residue may be scrubbed off with stiff brushes that could damage plastic.
- The transparency of glass lets you observe fermentation.
Cons
- Glass vessels are heavy and can be awkward to carry, especially when full of liquid.
- Glass is usually more expensive than plastic and can incur high shipping costs.
- Wet, heavy carboys need to be handled with care. Some homebrewers have ended up in the emergency room after dropping slippery carboys.
- Glass needs to be kept in a dark location or draped with a cloth to prevent skunking from direct sunlight.
Fermenting in glass used to imply narrow carboy necks that could make cleaning and dry hopping difficult. But new products such as the Big Mouth Bubbler make this less of an issue than it used to be.