Yeah, yeah.... I know not yet another "the importance of humidity control" threads but hey tis the season and in our busy repair biz we are already seeing the results of the ravages of humidity swings on guitars and other wooden instruments...
I also just read a thread about a recently built parlor that has strangely developed back back bow even when the builder observed strict RH control. Even though I know in the case of the parlor RH is not likely (but still possibe....) an issue I wanted to restart or jump start the conversation about how important it is to pay attention to humidity when building so that your creations don't grace our shop's door step in need of care to deal with cracks, poor action, sharp fret ends, loose braces, and most importantly, always....., unhappy clients.
I know that in the case of the parlor with back bow the OP said that they have their RH in check but I wanted to post this anyway because what you are experiencing with your parlor we see a lot of this time of year. And of course there are newer members here who may not have been subjected to a healthy dose of RH rant syndrome so this post is mostly for them.
Summers over, it's getting colder, furnaces are on and homes (and shops...) are drying out. Folks including our clients at times believe that they have RH control in place because they have a hygrometer, often a digital, that they rely on that says that everything is honky dory... So they or we believe that all is well until we get out our ax and low and behold the neck is in back bow, the top's dome is less than it used to be in prouder days..., and perhaps some fret ends are now proud of the neck just waiting to be annoying when the current steward plays the thing. The guitar has dried out OR was built with RH higher than the desired regional range and because of reliance on a standard, a hygrometer that is not accurate, all of this rears it's ugly head now with a seasonal change.
Last weekend I did my annual hygrometer check with my lab standard Psychro-dyne and the results were humbling... A Caliber III hygrometer with new battery read 8% low... a no name digital ready 11% high... my primary humidifier with digital display was 5% high and my Abbeon Cal that is my go-to hygrometer was 1% high indicating that it did not need calibration at this time.
At our shop my old Caliber III was also checked and was 15% out of range. I used to think that these Caliber III's were pretty good and bought three of them. My experience has been different though in so much as the CIIIs do seem to be pretty close when new but because they reply on an electro-chemical reaction over time the chemicals used seem to break down causing substantial drift that we can and have measured with lab standards such as the Psychro-Dyne. Additionally with the CIII hygrometers when new they can be pretty accurate in the range of say 40 - 50% but out side of that range the ones that I have were way off....
Most importantly though the point is that unless we have a quality way to measure RH and see how accurate or not... every hygrometer we are using really is the RH in the guitar's environment may not be what we think that it is and this includes when it was built.
Our clients tell us that they have whole house humidifiers, you know the ones that the belts or wicks get all nasty in a month and stop working.... or they have a K-mart hygrometer or this one or that one, etc. but in all truthfulness unless one utilizes testing such as a wet bulb test or other quality lab standard methods or devices you will never really know what you have and subsequently how well your instruments may hold up over time and with the abuse that most instruments experience at at least some point in their lives.
There are lots of threads on the OLF about humidity, I know long winded me participated in many of them. You will find, if interested, simple ways to know what you are dealing with in terms of how accurate your hygrometer is.
And for those who fancy building without any sort of RH control be advised your 100 - 200 hours of lovingly laboring to create your heirloom instrument may not result in the intended great instrument if the thing is sensitive to RH swings, prone to cracking or playability issues. So please as someone who has to be the one to tell Mr. and Mrs. Customer that the reason they need to pay us or someone else to repair the top crack, file down sharp fret ends, or rehumidify their instroment before it can be set-up again is that it was built without observing RH control let's get it together for everyone's sake. Commercial builders also do not need the warranty claim nightmares that result as well....
Here is a pic of my Psychro-Dyne: a couple drops of water on the wick and let it run for 5 minutes and I know what the RH is at the moment. Easy, accurate, and helps me sleep better at night knowing that my own creations were built with RH control in mind.
Thanks!
![[headinwall]](./images/smilies/headbangwalluf8.gif "Mad")
and second because many of the things that we use such as finishes, glues, etc. can have issues curing in cooler temps. Since we use HHG frequently too the warmer the longer the already short open time is. There is a reason why some of the violin guys have hot rooms, closets kept at around 100F to extend working time for difficult glue-ups.
I do love the visibility from a distance.
Flatsawn ebony might, but I'd doubt it with quartersawn spruce/rosewood/mahogany.
.......!!!