They should be sealed in plastic bags and treated with SO 2 to prevent mold growth. They should not be stored for more than three months without reprocessing. This is particularly true of drier corks. Inspect the corking jaws regularly for scratches, nicks or flaws. These will cause creases or other damage to the cork, allowing leakage or seepage.
Leakage often results from fill heights that are too high.
There must be a head-space of at least 5mm after bottling. This is a critical factor in bottling. Pressure above one bar will exert pressure on the cork and may cause leaking. 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.