Wines ferment in two stages. During primary fermentation, a great deal of gas is generated as yeast consumes sugar, and for this aerobic process to happen most efficiently, the must (juice, sugar, yeast and water mixture) needs exposure to the air. Leaving the liquid in a plastic pail covered with plastic wrap permits oxygen to enter and carbon dioxide to escape, at the same time preventing microorganisms that might spoil the wine from getting in. After the length of time specified in the recipe, typically three to five days, plastic soda bottles can be used to hold the wine during the secondary stage of fermentation.
Siphon the must from the pail into clean, odor-free plastic soda bottles. As much as possible, avoid siphoning up the sediment settled in the bottom of the pail.
Place the air-lock stems into the holes of the rubber stoppers.
Insert the stoppers into the mouths of the bottles.
Fill the air-lock stems half full with water and put the dust cap back on it. The water creates a barrier, allowing gases generated by the ongoing fermentation, which will be reduced from the primary stage to be released, but blocking out contaminants.
Leave for the length of time specified in the recipe in a warm, dimly-lit place. The ideal room temperature is 70 to 75 degrees Fahrenheit.
Rebottle the wine. Avoiding the sediment at the bottom, siphon the wine out of the fermentation bottles and into two clean soda bottles.
Drop one Campden tablet into each bottle. When wet, these tablets release sulfur dioxide, which sterilizes the wine, helps preserve the color and stops the fermentation process, but doesn't affect flavor. Screw caps on the bottles and leave them to age for the length of time recommended in your recipe.
Air locks and rubber stoppers in a range of sizes are carried by craft wine shops and on average, cost about $2 (or less) each as of 2010. If a stopper is too large, reduce the size by paring with a sharp knife. The prices of siphons vary according to models, but most are under $10 as of 2010. It is also possible to make all of these yourself. To find out how, type "DIY air-locks (or) wine stoppers (or) siphons" into a search engine.
According to wine-making products supplier E. C. Kraus, the belief that wine should be isolated from air during primary fermentation is a common misconception. During this stage, more carbon dioxide is produced than any air lock can handle.
Brewery Lane notes that some people complain that the taste of wine in plastic bottles is inferior and cautions that wine shouldn't be stored in them longer than 12 months.