A cigar hygrometer can work in various different ways, but the two most common types use a synthetic hair, or two separate metal plates that use water to produce electricity, to control when the humidor turns on and off. The humidor is a component within most cigar cases that maintain the level of humidity within the enclosed structure at the optimal levels that allow the cigar to retain its original air dried flavor. One common problem associated with cigars is that they dry out very easily, which changes their flavor and smoothness. The humidor ensures that the cigar is fresh, and the cigar hygrometer acts as an on and off switch for the mechanisms that work the specific humidor.
One of the most basic types of humidors available is the analog type. The cigar hygrometer in this applications works by applying a scientific concept to a basic humidor. Science has shown that hair, synthetic or real, when dried out, will take in moisture from the air in order to increase its moisture content. With people and animals, this allows the hair to grow properly by causing it to lengthen. The analog cigar hygrometer uses this phenomenon by having some type of synthetic hair wrapped around the bottom of a spring loaded switch. As the hair dries out and begins to take in moisture it will lengthen, which activates the spring loaded switch to open. After the moisture levels within the hair rise to the maximum set heights, the hair will begin to dry out again, shutting the switch off. This cycle while continue for as long as the humidor is used, or until the parts wear out and need to be replaced.
The second type of humidor that is used, which most commonly is found in specialty retail stores throughout the world, is the digital variety. The digital cigar hygrometer works by having two metal pieces placed separately, but still interlocking, and using the principal of water as an electrical conductor. These metal pieces are mounted onto a silicon plate where wires connect the battery to a computer chip that stores programmed information. When a set humidity level is needed, the chip will be set to a specified level, and when the humidity needs to increase, droplets of water will fall onto the silicone plate. The more water that is present on the plate, the higher the humidity levels will rise. Once the given humidity levels are reached, the water will stop falling onto the plate, cutting off the electrical connection until the humidor once again needs to turn back on.