In period, fermenters ranged in size, shape, and function. In Western Europe, in the later half of period, fermenters were large wooden vats or tuns, with little or no attempt to isolate the contents from the outside world. This proved to be beneficial - with no knowledge of how yeast worked, brewers didn't physically add it to a ferment until late in period. Yeast was usually introduced to a ferment as wild yeast, or as a pre-existing culture living in the fermenter. This tradition is continued in the Lambic style of beer in Belgium.
Today, the SCA brewer has a little more control over what goes into a brew. If you're willing to experiment with open air brewing, it is possible (Cooper's Brewery claims to do it on a commercial scale), but for ease and convenience, you're probably better off getting a standard fermenter. It's easiest to buy these at your local brew store, in order to buy all the appropriate fittings.
The main decisions to be made are in choosing the material and size.
Glass provides a nice hygenic surface, which is easy to keep clean. Glass doesn't impart any flavour to beverages that require a long maturation, such as slow meads or wines. Glass is also useful for inspecting a brew for clarity and appearance. Important things to consider before purchasing a big glass fermenter are:
- glass is heavy
- glass fermenters don't come with a convenient handle
- they need covering during the ferment (to prevent light strike)
- they need a siphon for racking or bottling
- can smash/explode in a spectacular/dangerous fashion
- price (carboys can be relatively expensive)
American brewers tend to favour glass fermenters, and frequently recommend them - glass carboys from water fountains are common and inexpensive. Glass fermenters come in several sizes - the rounded demijohn, the larger carboy, and other random sizes.
Plastic is cheap, convenient, and very available. A tap can easily be added to a plastic fermenter, allowing easy bottling and racking. Important things to consider before obtaining a plastic fermenter are
- the plastic must be food safe
- that damage/scratches on the inside of the fermenter can cause hygiene issues
- plastic fermenters can add a 'plastic-y' taste during long fermentations
- that the handle isn't indestructible - be careful when lifting a plastic fermenter
- transparent plastic requires covering during fermentation (to prevent light strike)
2 litre softdrink bottles are often used with some success by the beginning brewer.
Think about the size of your average brew before purchasing a fermenter. While a decent safety margin is important, excessive air space may cause problems with oxidation.