The Proper Use of Corks

Bottling Techniques

CORK STORAGE: Corks need cool, dry storage away from chemicals. They should be “sealed in plastic bags and treated with SO2 to prevent mold growth” and shouldn’t sit unused for over three months.

COMPRESSION: The cork diameter should compress no more than 33%. Exceeding 16mm compression on a 24mm cork risks damaging its internal structure, preventing proper expansion and sealing—particularly problematic for drier corks.

CORKING JAWS: Equipment should be inspected regularly for damage. Scratches or nicks on the jaws transfer to corks, creating creases that allow leakage.

FILL HEIGHT: Inadequate headspace causes leakage. “There must be a head-space of at least 5mm after bottling” to accommodate wine expansion from temperature fluctuations.

INTERNAL PRESSURE: Temperature control during bottling is essential. Wine should never be bottled below 15°C, as warming it afterward forces liquid past the cork. Using vacuum corking equipment with pressure gauges ensures proper sealing.

BOTTLE STORAGE: Keep bottled wine cool (under 20°C), protected from sunlight and excessive dryness, which compromises cork integrity.

Quality Control

MOISTURE LEVEL: Optimal cork performance requires 5–8% moisture content, measurable with specialized meters. Too dry causes rigidity; excessive moisture invites mold and cork taint.

SENSORY ANALYSIS: Test cork batches by soaking individual corks in deionized water for 24–48 hours, then evaluating the water for contamination and consistency.