Natural Corks

Allying “nature” and “technology,” Evolution 2 is a natural cork washed with hydrogen peroxide, following an exclusive Gültig process. With its resin coating, the E2 offers the best corking characteristics–a better seal as well as an additional protection against “off-flavors.” The Gültig quality assurance SYSTEM guarantees complete control at every step of the cork production.

Natural Wine Cork

Length: Standard 38 mm, 44.5 mm and 49 mm
Diameter: Standard 24 mm
Tolerances: Length: average +/- 0.5 mm, standard deviation max. 0.4 mm, Diameter: average +/- 0.4 mm, standard deviation max. 0.3 mm
Wash: Environmentally friendly, without chlorine and oxalic acid
Sterility: Wine sterility by SO2 treatment according to Gultig’s process
Residual Peroxide: < 0.2 ppm
Extraction Force: Average 200- 400 N
Humidity: Adjusted to the customer’s bottling requirements +/- 1.5 %
Surface treatment: Silicone polymer, comply with FDA 21CFR § 175.300 and § 177.2600, EC 1935/2004
Option: Fire branding on the ends, branding on the side, resin coating
Other: Special sizes
Advised bottle storage: Upright or horizontal in a warehouse preferably at constant temperature
Advised period of storage: Depends on selected quality grade

Handling and Processing

Storage: Natural corks should be stored in a well-aired odor free area at about 18°-20°C.

  • If stored below 15°C, natural corks can become hard and brittle resulting in imperfect sealing.
  • If stored above 25°C, natural corks can become too soft. This could result in the corks coming out of the bottleneck.

Storage before bottling: Natural corks should be stored at least 24 hours before being used at 18°-20°C.

Bottles: Use only bottles whose neck has an inside diameter that corresponds with the following standards:

Wine bottles: DIN EN 12726
Champagne bottles: DIN 6094-5

Corking jaws: The corking jaws should be regularly examined for damage before and during use. Damaged jaws may cause creases and other irregularities to the cork; leakers and increased cork dust may result. When fully compressed, jaws should not close to more than 16 mm.

Corker: In order to avoid cork dust, the following parts of the corker should be carefully examined before use:

  • Hopper, or any moving parts of the hopper: to determine if any sharp edges are detected
  • Cork shoot or tube: to determine if any sharp edges are detected
  • Corking jaws: (see above)
  • Heated jaws should not exceed 80°C
  • Star wheel should be appropriate for the bottle diameter

The centering cone and plunger should be examined for exact placement above the bottle resulting in an optimum seating of the cork in the bottleneck.

Filling height: The filling height depends on the type of bottle, the cork length and the temperature of the wine at bottling: For a standard claret bottle with a 44 mm long cork at 20°C, there should be 55 mm of space between the lip of the bottle and the wine itself; this would be about 11 mm head space. With a cooler wine, the filling height is correspondingly lower; with a warmer one, correspondingly higher. (Please refer to our bottling fill level chart).

Internal pressure: The internal pressure of the bottle should be examined at regular intervals. For vacuum corkers, once per hour is advised. The needed resting time after corking depends on the internal bottle pressure.

Bottles neck up or laid down: About three hours after corking, the natural cork regains 95 % of its original diameter; after 24 hours 99 % of its original diameter. (Depending on the cork’s moisture, these times may vary slightly).

Ideally, to avoid leakers due to positive head pressure in the bottleneck, bottles should remain upright for 24 hours. In the case of pressure reducing devices such as CO2 injection or vacuum corkers, maintaining bottles upright for 5 minutes is adequate.

Storage and transport of bottled wines: Great variations in temperature during the storage and transport of bottled wine should be avoided. The changes in volume causes by temperature variations may result in corks moving up or down the bottleneck resulting in leakers.