The right humidity in a wine cellar: differences between barrel cellars and bottle cellars
Why humidity is so high in historic Bordeaux wine cellars
Anyone visiting historic wine estates in Bordeaux will quickly notice that humidity levels in many traditional cellars are significantly higher than in modern wine storage facilities. Relative humidity values between 80 and 90% are not uncommon. This often leads to the assumption that such high humidity is required for the optimal ageing of wine. In reality, however, the high humidity is primarily due to historical and practical reasons closely linked to barrel ageing.
High humidity protects oak barrels
In the classic Bordeaux châteaux, wine is often aged for many months in oak barrels known as barriques. Wood is a natural material that reacts to its surroundings. If humidity drops too far, the barrel staves can dry out and shrink. This increases the risk of leaks and evaporation losses.
High humidity keeps the barrels in a stable condition while also reducing the so-called "Angel's Share", the natural loss of wine through evaporation. For this reason, many barrel cellars were deliberately built underground, where high humidity levels remain stable throughout the year.
| Area | Typical humidity |
|---|---|
| Barrel cellar (barriques) | 80-90 % |
| Bottle storage | 60-75 % |
| Modern climate-controlled wine cellars | 60-75 % |
The frequently cited high humidity levels of historic Bordeaux cellars therefore serve primarily to protect the wooden barrels and not the later storage of bottled wine.
Much lower values are sufficient for bottle storage
Once a wine has been bottled and sealed with a cork, the requirements for the storage environment change significantly. The wine is now contained within a closed bottle and is no longer in direct contact with the surrounding air.
Humidity now mainly serves to protect the natural cork from drying out. However, extremely high levels are not necessary. A relative humidity above 50% is already sufficient to ensure that natural corks retain their elasticity. In practice, values between 60 and 75% have proven ideal.
Excessive humidity can even have disadvantages
While high humidity is beneficial for barrique barrels, it can have undesirable effects during bottle storage. At levels consistently above 80%, labels often begin to wrinkle or develop mould. Cardboard boxes, wooden cases and other packaging materials can also be affected by excessive moisture.
Collectors of fine wines often place great importance on the condition of bottles and labels. To preserve the value of a collection, humidity levels between 60 and 75% are generally far more suitable than the conditions found in a traditional barrel cellar.
How can I increase the humidity in my cellar?
In wine cellars that are too dry, with humidity levels below 50%, a Hygromaster or humidifier can be used. However, it should be noted that such devices generally achieve a humidity level of around 65% at a typical wine cellar temperature of approximately 12°C. This value lies within the optimal range for wine storage and helps prevent corks from drying out.
Temperature is more important than humidity
A common misconception is that particularly high humidity improves the ageing of wine. In reality, the actual ageing processes take place inside the sealed bottle. Humidity has very little direct influence on these processes.
Far more important is a storage temperature that remains as constant as possible. Temperatures between 10 and 14°C are considered ideal. The higher the temperature, the faster ageing processes occur within the wine. Significant temperature fluctuations can also place stress on the cork and negatively affect storage conditions.
A cool cellar with a stable temperature therefore contributes far more to optimal wine ageing than exceptionally high humidity levels.
Oak wine racks are ideally suited for wine cellars
The question is often asked whether oak wine racks can be used in wine cellars with higher humidity levels. In fact, oak shelving, beams and barrels have been used in wine cellars for centuries.
Solid oiled oak wine racks present no issues at the currently recommended humidity levels of 60 to 75%. Even at higher levels, no structural problems are to be expected, provided that adequate air circulation is maintained and condensation does not form.
For modern wine cellars, both high-quality oak wine racks and combinations of wood and metal are popular. They combine attractive aesthetics with high stability and durability.
Conclusion
The high humidity found in historic Bordeaux cellars is primarily the result of traditional barrel ageing. Oak barrels benefit from a humid environment because they dry out less and experience lower evaporation losses.
However, such humidity levels are not necessary for storing wine bottles. Humidity above 50% is already sufficient to keep natural corks adequately moist and elastic. Modern wine cellars are therefore generally operated with a relative humidity of around 60 to 75%. This keeps corks protected while preventing mould growth on labels, cardboard boxes and wooden cases.
For the long-term ageing of high-quality wines, the most important factors are a constant temperature, minimal temperature fluctuations and consistently stable storage conditions.