Last spring I bought two humidifiers for my house. The main thrust was for health benefits, but I also wanted to see how they would affect my guitars. Up to that point, I was keeping the guitars in their respective cases, with a case humidifier when not in use. When spring rolled around and the furnace was turned off, the guitars came out of their cases, and were placed on stands where they currently remain. Fast forward to this fall, and I've had the humidifiers on now for a little over a month. The temperature out side hasn't been crazy cold yet, so the humidifiers are managing to keep the relative humidity on the main floor at about 45%, and in the family room at about the same. As a result, I've been able to leave both of my electric guitars and my acoustic on their stands. At what humidity drop would you put the guitars back in their cases?