Difference between old-fashioned and Modern guitars br br Humidity advises br br br 1) br You should have a hygrometer (a simple one like this: br (*do not leave this sensor inside the case, it should be outside in the room you keep the guitar) br br br br and only if it is under 40 humidity place (generally in winter time) the simplest humidifier in the head of the guitar case re-filling it with water every 2 or 3 days. br br 2) br Here is the link for the humidifier: br br br ( this may be an useful link ) br br The difference between Classical and Flamenco guitars br br br ............. br br br br .......