Humidifying Guitars

Are case humidifiers good enough? I decided to find out for myself. Reluctantly, I drilled holes in one of my Taylor cases, so I could feed hygrometer leads inside with probes placed at various positions in the sound hole and around my guitar. The goal was to allow the case to close tightly, without pinching the leads or having the case cracked partially open.

I placed my 414CE, that I normally maintain at 45 to 50% relative humidity inside a Musik Tent, into the case and inserted a wetted, dampit style, humidifier inside the soundhole. Next, I placed hygrometer probes in the headstock area (1), near the neck/body (2), inside the soundhole (3), and on top of the body near the strap button/output jack(4). I placed a another probe outside as a reference. I then latched the case shut and left this setup to stabilize overnight. 

The next day, I noted the outside probe measured the ambient room at 32% RH. Normally, this time of year the inside humidity in our home located in Pennsylvania would be below 20%, but we're experiencing a mild winter as of Jan 13, 2019.

The initial results were a bit unexpected. Most of the readings inside the case were at about the same humidity as the room. Probe 1 read 29%, probe 2 read 32%, and probe 4 read 31%. Probe 3, inside the soundhole, read 40% RH. I'd expected this value to be considerably higher. 

I added a second dampit, which after a few hours increased the humidity to about 41% RH. This meant the overall variation in the case measured 11%, lowest at the headstock and highest inside the soundhole.  My preliminary observation is that even a fairly high quality, original Taylor case, does not offer much of a seal with the outside ambient relative humidity. Additionally, two dampit style humidifiers are unable to achieve a 45 to 50% RH target inside this case when the room is around 30% RH. It will be interesting to see if the difference in case and ambient humidity continues throughout Jan and Feb. More to come.