Relative Humidity Ranges for Solid Woods

[UkeinPDX]

I apologize if this has been asked before.

We all hear a lot talk regarding humidity and cracking solid woods if it gets too low. I hope someone has an answer for what ranges are acceptable for most woods, perhaps what woods have different ranges, etc.

In my house in Portland, relative humidity stays at around 33-45%, which I am hoping is decent for longevity of my nice uke. I keep mine hung up for decoration and easy access for daily play, and it would be a real shame if I had to keep it in the case with humidifier to keep it going long-term.

 

[robinboyd]

I've been told the humidity should be between 40% and 60%. My house sometimes drops to 35% and I get a bit nervous, but it has been OK so far. It is usually around 45%.

 

[Jim in Oregon]

Hi PDX:

Everything I've read suggests your ukes want to be kept in the 40-to-60 range. Of course, a lot depends on whether your instruments are of solid wood or laminated construction. Laminates don't require nearly as much care.

I have several ukes, guitars and mandolins made from solid woods, therefore want to be safe rather than sorry. I try to keep the whole area where instruments are kept in that range by using a household humidifier.

Also I have several ukes, etc. with humidifiers in their cases.

In a perfect world, I would hang up a uke or two that were made with laminated woods, but keep the others safe in their cases.

Jim

 

[hendulele]

It also depends on how your home is heated. If you have forced-air heat, make sure your ukes aren’t near the registers. The heated air is very dry and can cause problems.

 

[Kenn2018]

Great suggestions from the previous comments.

This is a recommendation I got from a luthier if I just had to keep my ukuleles out of their cases:

If you have new solid wood ukes that were made in a tropical or very humid climate, keep them in a case with a humidifier. Or, in a room with a whole house/room evaporative humidifier going. (Ultrasonic humidifiers leave dust.) Keep the room at 50% RH ± 5%. Get a good hygrometer.

Dial the humidity back to 45% after several months to a year. Then to 40% and you should be okay after a year or so. Your uke will have shed some of the water from the wood and it will be acclimated to it's new home.

Check for fret sprout regularly. That's often the first sign that the air is too dry. Also feel and look at the top and back for cupping and bellying, a wavy surface. Sure signs of too little moisture. (The top and back can also warp due to too much moisture.)

I had two Pono tenors that I kept out in a room that was usually at 37% RH in the winter. They handled it just fine. The used Kanile'a K1-T I bought started getting fret sprout within a few weeks and I had to keep it in a case with an Oasis humidifier. Later I switched to a Boveda HumidPak. I now use Humid Pak humidifiers in all of my ukulele cases.

 

[Dohle]

The used Kanile'a K1-T I bought started getting fret sprout within a few weeks and I had to keep it in a case with an Oasis humidifier. Later I switched to a Boveda HumidPak. I now use Humid Pak humidifiers in all of my ukulele cases.

I don't have much to add to the discussion as there's been lots of good suggestions already and humidity issues are discussed often in the forum anyway, but I wanted to focus on the comment above. In addition to the type of wood used (which was the subject of the OP in the first place), the condition of the wood is also a factor even if the type/species of the wood is the same. Kanile'a is a great example of which I have some personal experience myself. I've had two different Kanile'a ukes and both developed fret sprout even with proper humidification. And even when I brought one of them for fret work to my local luthier, who of course has a climate controlled workshop, there was further fret sprout which I found very curious. This lead to a couple of assumptions of the ebony Kanile'a had used for the fretboards of those ukes. Either they are using a different type of ebony / source of ebony for their fretboards or the ebony they use is simply not as old and matured compared to other manufacturers. Apparently, the stripy ebony that you can observe, e.g., on Pono ukes is generally older and more stable than ebony that is more uniform in its colour. Of course Kanile'a might be heavily staining their fretboards. As I said, this is mostly speculation. What is definitely certain according to my own experience, the ebony Kanile'a used on my two ukes was noticeably less stable than any other ebony fretboard on any of my other ukes.

 

[Peter Frary]

My Kanile'a K-1 (premium koa and ebony board) is of early 2020 vintage and hangs out in my living room at typically 55-70% humidity. During the rainy season here on Oahu it may hit 75 to 90% for a few days. No problems whatsoever with it or any of my many guitars and 'ukuleles. However, being built nearby, I suspect higher humidity is the norm for these woods.

The times I took my better instruments to the mainland where humidity was considerably lower—20 to 40%—all sorts of little buzzes appeared as the frets danced around. One guitar suffered spider cracks in the finish, even with a humidifier in the case. What I learned is luthier made instruments with French polish or nitrocellulose finishes and unfinished/unsealed ebony fingerboards don't fare well in humidity changes—the wood breathes too much. Factory/workshop instruments with solid woods but with plastic based finishes and finished/sealed fingerboards are nearly bulletproof and can even take beer splashes and light rain to no ill effect. My Hirade classical guitars even have a finished interior!

 

[UkeinPDX]

Wow this is great info everyone, thank you. I wonder if taking an instrument out of a humidified case and into dry air for a few hours during playing, and repeating every day might have some impact as well? Or would the instrument retain moisture for long enough for this to have no affect?