How the Oasis Digital Hygrometer/Thermometer Works
To get an accurate humidity reading for the guitar body, we recommend that you first lay the guitar case with the back to the floor and open the cover. Take a small piece of cloth, and place it on the guitar top to prevent the hygrometer from scratching your instrument. Or better yet, use the Oasis Guitar Hygrometer Holder specially designed for this purpose. Place the hygrometer on the protective cloth or holder so the sensor sits near the edge of the soundhole, and close the case. Since the hygrometer is not secured, take special care NOT to move the case while the hygrometer is in this position. For best accuracy, allow 4 to 6 hours for the humidity to stabilize and then take the reading immediately after you re-open the instrument case.
Because the presence of a humidifier may somewhat distort the humidity reading, take readings both with the Oasis humidifier in place and without the humidifier. A well-humidified guitar in its case will have relatively stable humidity readings, so you don’t have to measure the humidity all the time.