THE PROPER USE OF CORKS
This information is courtesy of JUVENAL DIRECT, INC. Napa, Ca.
CORK STORAGE: Corks should be stored in a cool place, away from chemicals or liquids. They should be sealed in plastic bags and treated with SO2 to prevent mold growth. They should not be stored for more than three months without reprocessing.
COMPRESSION: Corks should not be compressed more than 33% of their diameter. If they are compressed beyond 16mm (for a 24mm cork) the internal structure of the cork may be damaged, and they will not expand properly to make a good seal. This is particularly true of drier corks.
CORKING JAWS: Inspect the corking jaws regularly for scratches, nicks or flaws. These will cause creases or other damage to the cork, allowing leakage or seepage.
FILL HEIGHT: Leakage often results from fill heights that are too high. There must be a head-space of at least 5mm after bottling. This allows the wine to expand due to temperature variations without affecting the seal of the cork..
INTERNAL PRESSURE: This is a critical factor in bottling. Pressure above one bar will exert pressure on the cork and may cause leaking. Never bottle a wine whose temperature is below 15oC (59oF). Once that wine is stored at a warmer temperature, the pressure will force wine past the cork. In addition to the use of a vacuum corker, a pressure gauge to manually test the accuracy of the vacuum is strongly recommended.
BOTTLE STORAGE: Please help the cork to protect you wine by storing the bottled wine in a cool cellar, not to exceed 20oC (68oF). Keep wine away from sunlight, and avoid extremely low humidity which will dry out the cork and reduce the effectiveness of the seal.
MOISTURE LEVEL: In terms of the performance of the cork, moisture level is the most critical factor. If the cork is too dry, it will be too rigid to make a good seal. If it is too moist, it may allow mold to grow, creating cork taint and other undesirable characteristics. Variable moisture levels will also affect proper insertion depths of the cork during bottling. The ideal moisture level is from 5% to 8% and should be measured with an Aquaboy or DC20-11 meter.
SENSORY ANALYSIS: To avoid bad lots of cork, it is important to test the corks for sensory contamination. Using mil spec standards, soak each cork in 100ml of de-ionized water for 24-48 hours. Then smell the wine samples for contamination, sensory neutrality and consistency.
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