How to Size Carboy Corks
- 1). Measure the diameter of the spout of your carboy.
- 2). If you did not use a metric ruler to make the measurement, convert the inch measurement to millimeters by multiplying it by 25.4 and rounding. For example, if the measurement is 1.5 inches you would multiply that by 25.4 to get 38.1 mm. Then you would round that to 38 mm. Most corks are measured in millimeters.
- 3). Choose the corresponding sized cork. All corks are sold according to their diameter measurement. If they are tapered they will include the diameters of both ends of the cork. If you are choosing a non-tapered cork, choose a cork of the same diameter as your measurement. If you are choosing a tapered cork, which is recommended for brewing, choose one that has a small diameter that is smaller than your measurement and a large diameter that is larger than your measurement. This will allow for a tight fit on the carboy.
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