All About Propylene Glycol, The Correct Humidor Liquid

All About Propylene Glycol, The Correct Humidor Liquid

Maintaining the proper humidity level in your humidor is essential for preserving the quality and flavor of your cigars. Propylene glycol (PG) is a popular solution for achieving this goal, ensuring that your cigars remain in optimal condition. Whether you are a seasoned cigar aficionado or a beginner, understanding the role of PG in your humidor can significantly enhance your cigar storage experience.

Cigars are hygroscopic, meaning they absorb and release moisture based on their environment. If the humidity is too low, cigars can dry out, leading to a loss of flavor and an uneven burn. Conversely, if the humidity is too high, cigars can become oversaturated, which can result in mold growth and a poor smoking experience. Using propylene glycol helps to maintain the perfect balance, keeping your cigars fresh and ready to smoke.

What is Propylene Glycol?

Propylene glycol is a synthetic chemical known for its hygroscopic properties, meaning it can absorb and retain moisture. It is widely used in various industries, including food, cosmetics, and pharmaceuticals, due to its ability to maintain moisture levels. This versatility makes PG an ideal component for maintaining the humidity in cigar humidors, ensuring a stable environment for your cigars.

In the context of cigar humidors, propylene glycol is typically used in a 50/50 solution with distilled water. This mixture helps maintain a stable relative humidity (RH) of around 70%, which is considered optimal for storing cigars. The PG solution not only helps in regulating humidity but also possesses antifungal properties, reducing the risk of mold growth inside the humidor.

How Propylene Glycol Works in a Humidor

Propylene glycol works by absorbing excess humidity when RH exceeds 70% and releasing moisture when RH falls below this level. This two-way humidification process ensures that your cigars are kept at a consistent humidity level, preventing them from drying out or becoming oversaturated. The stable environment provided by PG helps in preserving the flavor, aroma, and overall quality of your cigars.

Using PG in your humidor also helps prevent mold growth, thanks to its antifungal properties. Mold is a significant concern for cigar enthusiasts, as it can ruin an entire collection if not managed properly. The presence of PG in the humidification solution mitigates this risk, offering an additional layer of protection for your cigars. This makes PG a superior choice compared to using distilled water alone.

Benefits of Using Propylene Glycol

One of the main advantages of using PG is its ability to stabilize humidity levels. Unlike distilled water, which can cause fluctuations in RH, PG helps maintain a consistent environment for your cigars. This stability is crucial for aging cigars properly, allowing them to develop their flavors over time without the risk of drying out or becoming too moist.

Another benefit is mold prevention. The antifungal properties of PG reduce the risk of mold growth in your humidor, ensuring that your cigars remain in pristine condition. Mold not only affects the appearance and smell of cigars but can also pose health risks if inhaled. By using a PG solution, you can significantly minimize the chances of mold contamination, giving you peace of mind.

How to Use Propylene Glycol in Your Humidor

To use PG in your humidor, you will need to mix it with distilled water in a 50/50 solution. This can be done easily by combining equal parts of PG and distilled water in a container. Ensure that you are using distilled water to avoid introducing minerals and impurities that could clog your humidification device or promote mold growth.

Once the solution is mixed, pour it into your humidor’s humidification device. Make sure to saturate the device thoroughly, allowing it to absorb the solution. After filling, remove any excess liquid to prevent oversaturation. Place the device back into the humidor and monitor the humidity levels regularly using a digital hygrometer. This will help you maintain the ideal environment for your cigars.

For more information regarding seasoning a new humidor and using this PG solution effectively, please see our Humidor Seasoning Guide.

Maintenance Tips for Humidor Liquid

Regular maintenance is crucial for ensuring your humidor functions correctly. Check the humidity levels frequently using a digital hygrometer, and refill the humidification device every few weeks as needed. Consistent monitoring and maintenance will help you catch any fluctuations in humidity early, allowing you to make necessary adjustments before your cigars are affected.

Using PG solution requires less frequent maintenance compared to other methods, but it is still essential to monitor your humidor’s environment and make adjustments as necessary. Ensure that you clean your humidification device periodically to remove any build-up of residues or impurities. This will help maintain the effectiveness of the PG solution and prolong the life of your humidor.

Common Pitfalls and Misconceptions

A common misconception is that pure PG can be used directly in humidors. However, pure PG is not effective and can damage your cigars. Always use a 50/50 mixture of PG and distilled water for the best results. This specific ratio ensures the correct balance of humidity control, preventing oversaturation or drying out of your cigars.

Another pitfall to avoid is using tap water. Tap water contains minerals and impurities that can clog your humidification device and promote mold growth. Always use distilled water to ensure the longevity and effectiveness of your humidor solution. By avoiding these common mistakes, you can ensure that your humidor remains in optimal condition, providing the best environment for your cigars.


Using propylene glycol in your humidor is an excellent way to maintain the ideal humidity level for your cigars. It provides stability, prevents mold, and requires minimal maintenance. By following the proper mixing and application techniques, you can ensure that your cigars remain in optimal condition for a perfect smoking experience. Proper maintenance and understanding of PG’s benefits will help you get the most out of your humidor, ensuring your cigars are always ready to enjoy.


Q: Can I use pure propylene glycol in my humidor? A: No, pure PG is not recommended. Always use a 50/50 solution of PG and distilled water.

Q: How often should I refill my humidification device with PG solution? A: Refill your device every few weeks or as needed, depending on the humidity levels and the size of your humidor.

Q: Why is distilled water necessary for the PG solution? A: Distilled water is free from minerals and impurities that can clog your humidification device and promote mold growth.

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