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La newsletter de ProCork

L’alliance de la Technologie

et de la Tradition


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Natural Cork with Oxygen Transfer Technology

Cork is a natural product that elevates the spirit and can be perfection in a bottle.

It is the classic wine closure and precision and care is required when bottling.

Here are some handy tips for when you use it.

  1. Check the diameter of the bottle necks at the depth of the cork.

    • Check the inside diameter of bottles that leak. We have a hand held device to do that, so save some bottles and we can check it for you.

    • Cork’s ideal compression is 5 to 7 mm so if you have bottles with diameters significantly greater than 20 mm you need to change bottle supplier. It is worn out production molds causing the deviation.                                                                                                                           

  2. Check the bottle number.

    • The bottle must suit the cork length otherwise legal fill height will force you to overfill the bottle. We can help you match the numbers. (see here)                                                                                                                                   

  3. Check the dissolved CO2 in the wine

    • High levels of CO2 can cause over pressure in the bottle even before the wine becomes slightly fizzy and it can get very high if the temperature rises.

    • Ideally keep the CO2 less than 0.8 g/l

    • Also remember the ProCork OTR technology retains CO2 better so there less need to start with higher levels                                                                                                                            

  4. Check fill height during bottling. There is a simple trick to compensate for the wine temperature.

    • The best head space to leave is 15 to 20 mm at 20 C. That allows for short term reasonable temperature increases during delivery and storage.

    • If the wine is 10 C when filling the head space at bottling needs to be around 25 mm. There are temperature tables available. (see here)

    • The old practice of filling the wine close to the cork is technically flawed. We are happy to talk to you further about this.                                                                                                                                                                           

  5. Check the bottle vacuum every 30 minutes during bottling.

    • The benefits of vacuum in the headspace at bottling are significant, numerous and technical. We are happy to talk to you about this.

    • The vacuum needs to be minus one atmosphere for the best leakage performance.

    • The vacuum line needs a strong vacuum pump, reservoir tank, good diameter piping, not to many bends and no leaks to deliver the high burst of reverse gas flow required to evacuate the 8 ml of gas in the bottle neck in the split second after the cork seals the top of the vacuum head and before the cork then closes off the small vacuum hole.

    • There is a hand held pressure device to test the vacuum and it is critical to use it.

      • The bottling company should have one and if they don’t then change contractor immediately because they are not professional enough for the ProCork product you are trying to use.

      • You can buy your own hand held device for 80 euro.

    • If you cannot vacuum bottle for some reason talk to us about some other techniques to help reduce the leakage problems.                                                                                                                                                                       

  6. Check the storage temperature

    • Storage temperature ideally should not fluctuate and sit between 12 to 18 C.

    • Ship in winter so that temperatures do not exceed 25 C for significant lengths of time.

It’s a long list and that is why ProCork is a natural fit with precise and professional winemakers.


Contact: Dr Gregor Christie

Ave Santiago 84                 

Rio Meao Portugal              

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