How does cigar juice work?

Answer 1

The "juice" is a solution you add to your humidification jars in the humidor. This product helps regulate the humidity inside the humidor.

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"Cigar juice" is propylene glycol diluted with distilled water. All glycols (which are complex alcohols) absorb moisture from the air, or release moisture to the air, until the moisture level in the air and the water bound in the glycol are equal. Unlike almost all glycols, propylene glycol won't kill you if you ingest any. (It's used in medicines and some foods.)

If you have a compounding pharmacy in your area--it won't have the name of a chain on the door, and it'll probably be by the hospital--they will sell you a quart of pure propylene glycol cheaper than a bottle of cigar juice is. Add distilled water to it in a 1:1 ratio and put it in your humidifier. When you need to add more moisture to the humidifier, just use plain distilled water.