Campden tablets are manufactured from either sodium metabisulfite or potassium metabisulfite. We had sold the sodium variety several years ago but have switched now to exclusively using the potassium variety mostly because of thoughts of my doctor preaching to me about the benefits of reducing my sodium intake. In the same vein, we no longer sell the powdered form of sodium metabisulfite either. We now sell only powdered potassium metabisulfite.
The thought behind Campden tablets is that it provides a premeasured dose of sulfites for your homemade wine. The tablets should not be matched one to one with the powdered form of metabisulfite as the powdered variety is much, much stronger. Campden tablets are made with a considerable amount of inert material so that the home winemaker can precisely control the amount of sulfur dioxide (SO2) being added to their wine.
One Campden tablet will provide 65mg/L of sulfur dioxide if added to one gallon of wine must (or 13mg/L if added to five gallons of wine must).
Campden tablets are used for several reasons. First, when used in conjuction with backyard fruit, they help stifle the wild yeasts that are always present. This helps create a good, clean environment for the wine yeast you will be using. Second, sulfites can be used to slow the growth of bacteria which can get started in your wine (especially during the very early stage prior to the presence of much alcohol). Third, sulfites can be used to sanitize your winemaking equipment. In actuality, the powdered (or crystal) potassium metabisulphite works much better for this because this powder is much more concentrated than Campden tablets.
If Campden is added to wine (one tablet per gallon) at bottling, it will help to increase the shelf life potential of your wine.
To add Campden to wine must (or wine) simply crush one tablet (per gallon) and add the resulting powder to a small amount of hot water to help the tablet(s) dissolve. Stir until it is completely dissolved and then stir into your must or wine.
Visit us on the web at www.bluestemwine.com for a complete line of winemaking ingredients and home brewing supplies including both Campden tablets (the potassium variety) and Potassium Metabisulfite in crystal (powdered) form.