understanding relative humidity...and our guitars

[prezmc]

Question, well, several questions that start with a little background:

I have several hygrometers in a small room. One is built into the humidifier, and is set to 45% RH as a target (from it's perspective it maintains 43-47%). The other two just measure humidity and temp.  One is Acurite, the other Daddario.

The acurite often matches, or stays within 1-2% of the one on the humidifier, and the other always shows much lower...and eats batteries.  Since the first 2 tend to match, i base my room humidity on them. 

The other day - I ordered a TaylorSense.  It's a multisensor that tracks humidity, temp, impacts, etc.  Great idea.
I installed it this morning, and setup with my phone was super easy.

BUT.....

It reads 49-51% humidity all the time.  I moved it to another room, that the other sensors read @ 39%....and the TaylorSense...reads 48% after being there over an hour.

So here are my questions:

1: Is it normal for a humidity sensor inside a guitar to read 5% higher than an ambient room sensor?
2; Does a guitar hold onto humidity for a long while before dropping to whatever a room is at?
2: Does anyone here have experience with the TaylorSense?

Thanks!

[gfowler]

My experience is that each of my hygrometers read differently in the same settings. Wondering if a more expensive hygrometer would be worth it. Inside the case, the readings usually seem to be higher than the room. I ordered the TaylorSense about a month ago and like the concept -- though, every few weeks it loses the bluetooth connection and the battery needs to be pulled to reset. Be interested in what others have to say on this topic. :-)
 

[Earl]

A man with two watches never knows exactly what time it is.....  I pay attention to the room conditions because the case will eventually equalize with the room.  No case is truly airtight or moisture-proof. 

After chasing the readings inside cases for a long time, I gave up on in-case hygrometers and the weird readings.  I watch my guitars for symptoms of dryness and add moisture as needed.  Where I live excess humidity is never a problem.  In the lab I have calibrated hygrometers using a sling psychrometer to measure wet bulb and dry bulb temperature, then you can look up the RH reading and adjust your device accordingly.  These days, if there is a question about a given device, I put it outside for a couple of hours to stabilize and look up the National Weather Service hourly observation - it's nice being just three miles from an airport and having access to official calibrated observations.  If they say 45% and my device reads anywhere between 40-50%,  that is close enough for my guitars.

My car has a display of instantaneous gas mileage, which fluctuates wildly as I accelerate, decelerate, go uphill or downhill, etc.  But all I really care about is how many miles are left in the tank at the moment and the average mpg at refills.  There is such a thing as too much data.

[prezmc]

Yea, my testing isn't within a case @ the moment. Guitars left in cases tend not to get played much in my house.

Just trying to understand more and achieve some amount of consistency in a common space (my office).  The whole point of this taylorsense thing is to alert you when conditions go outside of normal - like when I pack it up and go somewhere to play, and it may sit out for a long period.  The problem where I live is winter.  Temps get extreme, and heating causes inside humidity to drop like a rock, irrelevant of outside conditions (which are quite warm compared to the past month: 27° F 70% RH).  If a hygrometer is incorrectly reading much higher than real RH, by the time it alerts about things getting too low - you might already have buzzing or a crack. Like right now, the nest thermostat in my front room says RH is 34% (well below the 45-55% that the manufacturers recommend for storage).  My guitar is currently sitting on a stand in that room, and is saying 51%.  That's a staggering discrepancy. Far beyond a 1 minute discrepancy in two mechanical watches!

I get the too much data / analysis paralysis reality.  But, this is an experiment for me and experiments lean on data and understanding.  So, I brought it here for other people's experience.

[Earl]

I did not mean to dismiss your inquiry, so I'm sorry if it came across that way.  I'm just pointing out that plus/minus 5% indoor RH on an extended basis is close enough, and don't get hung up on temporary hourly excursions.  My indoor hygrometers routinely read 37% in the morning when the heat is turned down, and my guitars have suffered no damage.

Outside RH is mostly irrelevant to indoor RH.  I can easily believe your 35% RH at room temperature.  Google the psychometric chart (used in HVAC) and it will show the RH at two different temperatures.  At 27° and 70% RH outside, by the time you heat that air up to 70° indoors, my chart gives me about 17% indoor RH -- assuming constant mass of water per cubic foot (closed system).  But homes are really not closed systems.  We breathe, shower, cook, and have potted plants that we water.  The important point is that wood's moisture content is governed by RH, not absolute humidity.  RH of 50% means that at that given temperature, the air is holding 50% of its saturation value - its maximum capacity for water vapor without condensation (dew point).

[prezmc]

No worries! no offense taken.  just realized I never explained my goal in this effort.

That chart is interesting, I have never seen that. Very helpful info. Now down a rabbit hole of YouTube videos on the topic.

thanks!

[Frettingflyer]

One thing to consider is that many of us never knew about proper care for years and our older guitars mostly survived. That said I found my solution is a humidified cabinet instead of cases so they are all easy to grab. I also installed 4 Taylorsense units before resorting to the cabinet solution so thought I would chime in on them. Currently with only 3 connecting from here(4th battery getting low) I have 2 at 47% and one at 49%. I would be the 4th would be around 53-54% because it is always a bit higher than the others even though they all live in the same cabinet which currently shows 46% on it’s meter.
In short I have 3 that largely agree and one that mostly reads high out of 4 Taylorsense units. This time of year I keep my CF instruments out but I may drag out a Taylor for a few hours in the house and see how it changes to update this post.
Too much data can just lead us to worry too much though.
update- after sitting out an hour and a half or so my guitar is down from 49% to 43% on the Taylorsense.

[prezmc]

thanks for the info. Mine is definitely reading on that higher side, and doesn't really change much even with putting in a dry location.  The other hygrometers around definitely change when moved to non-humidified rooms! the meters are saying 35%...guitar says 46%.  rofl.  I've emailed Taylor to ask their thoughts. 

Speaking of proper care, and what sort of sparked my interest in the data - I spend time @ my local guitar store every week.  My son has been taking lessons for a while, and I've recently started some lessons again to get over a slump I've been in.  Every winter here, the repairs that show up from lack of humidity are staggering.  The number of really nice acoustics that are severely recessed and often have related cracking in one or more places blows my mind. 

About a year ago, a friend of mine said his OM-28 was buzzing all over, so I took a look @ it, and it was pretty dried out, causing the top to sink a bit, thus his issues.  This guitar would spend time in a somewhat humidified office, or a case....but often sit open on a stage in a very dry building for several hours, multiple times a week.  I took it home, and put it in my office....and it took a week for it to come back to shape. Thankfully, no cracks. He didn't realize the issue, until the buzzing got too annoying. I think many players are similar.  The idea of an automated alert to tell you when the guitar is getting too dry, is great idea, I think.  His office now runs a large humidifier all winter, keeping his collection of guitars happy.

[Strumming Fool]

I live in Arizona. My six Taylors (each humidified with two Oasis case Humidifiers) register at 40-44 % RH on their case hygrometers, while the room RH is 28-35% on the room hygrometer. These ranges cover all four seasons.  As a casual observation, it appears that my older guitars (1997, 2011 and 2014)  "drink" less than the newer guitars (2018,2019 and 2020), which would make sense as the older ones are more stable at their ages. The new ones should catch up in a few years. Hope this helps.