How to calibrate and measure accuracy of the hygrometer Share on Facebook Share on Twitter Share on Google+ Share on Reddit Share on Pinterest Share on Linkedin Share on Tumblr Calibrating the hygrometer It is important to take into account that this step is not necessary if a hygrometer is pre-calibrated, and it is only necessary in case it has been hit during its transport.There are two methods for calibrating an analogical hygrometer:The most recommended and accurate method is to put the hygrometer with a salt solution in a little plastic box. A spoon of salt should be added and it has to be dampened with a few drops of water.The salt should not be dissolved, but absorbing the water. After that, place the hygrometer and the salt in a plastic box well sealed and wait for 8 hours until the box reaches 75% humidity. Later, fit the hygrometer hand with a screwdriver to indicate the 75% humidity.Another possibility is to take the hydrometer off the humidor and wrap it in a damp cloth. You have to wait for 1 hour approximately and then, adjust the hygrometer with a screwdriver in 96% relative humidity.How to measure accuracy of the hygrometerIt is necessary to calibrate analogical hygrometers before its first use. Although some hygrometers are not necessary because they are calibrated before shipment.Even calibrated hygrometer may be re-calibrated in case of damage during its transportation. As said before, the accuracy of hygrometers of metal springs is limited. On the contrary, the accuracy of digital hygrometers is higher and they are optimized for the high humidity level of the inside of a humidor.Even though it is important to notice that in comparison to measuring temperature, humidity is difficult to measure. Even hygrometers for professional laboratories, at prices of more than $ 100 have only an accuracy of 2% approximately. Analogical hygrometers should be re-calibrated once a year.If a humidor is equipped with the traditional hygrometer of metal spring, it is important to pay attention to changes in the humidity level. If it is used acryl polymers or sponge-based humidifiers with propylene glycol solution (see explanations about humidifiers), humidity must be stabilized automatically at about 70%.It will be only necessary to refill the distilled water or propylene glycol (for sponge-based humidifiers) as soon as a humidity drops. If there any doubt, when touching cigars will allow to know if they are stored in an appropriate environment.After buying a humidor, a group of preparation steps must be followed before the storage of cigars because on the contrary, the cedar lining will extract the humidity of cigars. Best humidors are available in two variants.The standard variant consists of a spiral hygrometer and sponge-based humidifier with the propylene glycol solution.The premium equipment includes the precision of the hygrometer of acryl polymers that uses distilled water.