General Humidity and Care Questions

I have 3 wood ukes and I keep them in cases with humidifiers. When I practice, I do so in my basement. I have a dehumidifier in my basement that keeps the room at 45% humidity when it's running. When it's not running, the room can get to 75%-90% humidity, but it's always running because we have basement moisture issues when it isn't running.

I am basically asking if I can hang the ukes on the wall in the basement in a 45% humidity room because I'd rather have them seen than closed up in cases. I am willing to experiment with the dehumidifier and maybe increase to 50% humidity, but I would rather ruin my ukes than my home's foundation so if 50% isn't enough, I don't think I want to go any higher and I'd just keep them in cases.

My ukes have the kind of humidifiers that sit on the strings and dip into the body. I would be fine with keeping these humidifiers clipped to the strings while the ukes are on the wall, so the inside of the body is still being humidified. Of course this would mean more frequent refills of the humidifiers if they're exposed and the dehumidifier is running in that room all day, but I don't mind that maintenance step.

Also, I'm expecting a banjolele in a few days. Does this need to be humidified?

To be clear, they would be out of their cases on the wall.

I don't understand why you want to humidify your ukes when you dehumidify your house. You need soundhole humidifiers when your house is too dry. When your basement is at 45% that's about perfect for ukes.

merlin666 said:

I don't understand why you want to humidify your ukes when you dehumidify your house. You need soundhole humidifiers when your house is too dry. When your basement is at 45% that's about perfect for ukes.

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It is possible I have a general misunderstanding of when and why one should humidify a uke. I started humidifying on the recommendation of a Guitar Center technician when one of my ukes was playing inconsistently up the neck when I first got it. For what it's worth, the sound of the uke did improve once I added the humidifier (they gave me a free one) so I began putting them into my other ukes too.

Sounds like I'm probably ok to hang these down there with the soundhole humidifiers in?

A RH of 45% is just about perfect. A stable 40% or even 35% is ok as well, big swings and lows of below 30% is what can cause damage. Feel free to keep those ukuleles out. I keep all solid wood instruments out of their cases with anything above 35% and no issues in over 6 years

DownUpDave said:

A RH of 45% is just about perfect. A stable 40% or even 35% is ok as well, big swings and lows of below 30% is what can cause damage. Feel free to keep those ukuleles out. I keep all solid wood instruments out of their cases with anything above 35% and no issues in over 6 years

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Thank you all for your responses, this makes me really happy.

DownUpDave said:

A RH of 45% is just about perfect. A stable 40% or even 35% is ok as well, big swings and lows of below 30% is what can cause damage. Feel free to keep those ukuleles out. I keep all solid wood instruments out of their cases with anything above 35% and no issues in over 6 years

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This is about where I keep my instruments as well. 40-45% or so. If 30-35% is at the lower limit, what would you say is the upper limit? I would imagine @donboody’s 75-90% before dehumidifying is too high.

The concern with humidity is foremost about dry air where the wood shrinks and then has a high risk of cracking, and frets can stick out of the neck and cause injury. The second concern is changes in humidity where repeated swelling and shrinking also can cause damage to the instrument, and aside from the need to retune also leads to changing action and intonation. I don't think that high humidity is a concern, because the wood can only absorb a limited amount of moisture and then stabilizes. If the uke is set up correct for constant high humidity then it is fine. However if moisture is really high then electronics and metal parts can corrode and there is chance of mildew growth.

I'm also curious about temperature changes. Not a big deal in the summer, but in the winter months we use a space heater in the basement that does a great job getting the room up to 70 degrees or higher, but when it's not on (typically overnight) the temperature probably drops to about 60 degrees. (All fahrenheit). I know 70 degrees and 60 degrees are not extreme temperatures, but should I be concerned about a daily 10 degree shift both ways?

In general, wooden instruments do not like extremes. They also don't like fast changes.

The numbers I have heard are that you want your humidity to stay between 30-60%, and you want to sort of aim for the middle as much as possible. But you also want to keep in mind the "fast changes" part. I would gladly take a constant 40% rather than a rapid swing back and forth between 30% and 60%. Fast swings are just bad news.

As for temperature swings, I have much less experience with this one. 60 and 70 degrees are not really extreme as far as temperatures are concerned. If you are riding a 10 degree temperature change over 12 hours, then another 10 degrees back up over another 12 hours, that isn't much of a big deal, I suspect. But do keep in mind that temperature and humidity are related.

What we actually measure is "relative humidity"; that is to say how much moisture does the air currently have *relative* to how much it could hold. Warmer air can hold more moisture, so if we warm the air in your room (without giving it any other source of moisture) the relative humidity will go down. The air could easily hold more moisture, so moisture might make its way out of, for instance, the wood of your instrument.

I stress that part about "without giving it any other source of moisture" because this all might seem a little counterintuitive. In the summer, things feel more humid and in the winter they feel more dry. But if the air can hold more moisture when it is warm (that's why the *relative* humidity drops if we warm the air in a room), shouldn't it feel more dry? Well, in the summer months there are two things happening. We have more moisture in the environment (it tends to be more rainy in the summer) and we have more total moisture in the air (since it can hold more, it does.) In the winter, the opposite happens. Less liquid precipitation, and the air can't hold as much, so it is drier. (That will also dry out instruments, as there is more moisture in the wood than the air, so water makes its way out of the wood.

Modern heating and A/C then come along and muck with all of this. Forced air heating in the winter dries out the air even more, so we all end up humidifying our instrument cases. And A/C systems pull moisture out of the air, so we end up humidifying in the summer too. Basically, I get about 3 weeks in the Spring and Fall when I don't worry about it...

This is all to say that it is somewhat complicated, and I can't promise that everything will be just fine in your situation. The best you can do is take some careful measurements of temperature and humidity where you want to store your ukes, and as long as you are comfortable with both the range of values and the rate at which they change, go for it.

As for me, it isn't one of those three weeks right now, so I am off to check the humidity in my uke cases!

donboody said:

Also, I'm expecting a banjolele in a few days. Does this need to be humidified?

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The neck/fretboard is probably still made of wood. If humidity in your location is an issue (doesn't seem to be), you'd want to humidity the banjolele, too, so that the fingerboard doesn't shrink. Worst case would be that the neck wraps.

donboody said:

I'm also curious about temperature changes. Not a big deal in the summer, but in the winter months we use a space heater in the basement that does a great job getting the room up to 70 degrees or higher, but when it's not on (typically overnight) the temperature probably drops to about 60 degrees. (All fahrenheit). I know 70 degrees and 60 degrees are not extreme temperatures, but should I be concerned about a daily 10 degree shift both ways?

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Small changes like between day and night or inside and outside in summer are normal and no concern, but may lead to your uke going out of tune a bit. But as others mentioned it is good to avoid extreme temperature changes, such as leaving it in a car or outside in extreme cold winter and then bringing it inside to an overheated house. If I have to do that I try to wrap it in a blanket so it cools or warms slowly.

I appreciate everybody's input. I ordered some hooks and I'll be hanging them on the wall this weekend unless somebody wants to tell me I'll regret it. In general it sounds like this is a pretty fine idea given the conditions of my basement.

I had two tenor ukes that absolutely did not like humidity of 55 - 60% RH. The tops and backs started to get wavy to the point I could feel the bracing underneath as ridges. This was from keeping an Oasis Uke Humidifier hanging from the strings in a hard case. Ditto with a Humid Pack hanging from the strings. The hygrometer said the RH inside the body averaged 57%. I moved the humidPack to sit by the heel of the uke and the RH stays at about 45% inside the uke.

I keep a room humidifier going all winter in the rooms where I have my instruments in cases or one or two hanging on wall hooks. They keep the RH at about 43 - 45%. In Late Spring, & Late Fall, the humidity can get up to 65%. We keep the A/C on most of the Summer and the R/H stays at about 47 - 50%.

A sure sign of a uke being too dry is "fret sprout". Where the fret ends start to protrude from the edge of the fretboard.
Too much humidity, over 60% can have bad effects on your ukes as well. The wood swells and can push up frets, bellying or waves in the top or back. And even warp the neck because the fretboard and neck are usually different woods and expand and contract at different rates. As are the glues and adhesives used.

If you see any signs of these when you play your ukes, pop them back in their cases and humidify them or reduce the humidity as needed.

Worst Case: I loaned a friend a Pono Cedar/Ebony tenor to play and see if he was interested in buying it. He kept it in a room all winter (lots of sub zero days that year) at 50 degrees F. When he returned the uke in the Spring he asked if it was ok because one of his had split at the seam on the back. I looked it over and it was fine. I put the case in my room and hung a humidifier from the strings thinking it likely needed humidifying. Two weeks later, I took it out to play it and discovered a 2 inch split in the back from the heel down. I had it repaired. I refilled the humidifier twice and all was fine. The third time, the entire back had split, as well as the seam at the butt. Except, the two inch split I had repaired. It sounded okay when I played it, the back longitudinal brace and the butt block were holding it together. I think the Pono had dried out too much, and the sudden influx of high moisture was too much too quickly and as the wood swelled, the glue holding the halves together failed.

I wound up giving it to someone who had lost his job due to COVID and said he had to sell his ukes to pay bills. So he would at least have something to play until his situation improved. He said he took it to play when he visited his mother who had dementia and was in a care facility.

Cluze said:

The numbers I have heard are that you want your humidity to stay between 30-60%, and you want to sort of aim for the middle as much as possible.

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Kenn2018 said:

I had two tenor ukes that absolutely did not like humidity of 55 - 60% RH. The tops and backs started to get wavy to the point I could feel the bracing underneath as ridges.

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I usually just hear recommendations for a target percentage in the 40s to 50s, but I was curious about an upper and lower boundary. Having a rough range of 30-60%, with some instruments requiring a smaller range is helpful to have in the back of my mind.

Now that I think on it, though, it makes sense that not all ukuleles would be the same. Especially since they’re made from different woods, which come from different climates, and are built in varying controlled environments.

rafter said:

I usually just hear recommendations for a target percentage in the 40s to 50s, but I was curious about an upper and lower boundary. Having a rough range of 30-60%, with some instruments requiring a smaller range is helpful to have in the back of my mind.

Now that I think on it, though, it makes sense that not all ukuleles would be the same. Especially since they’re made from different woods, which come from different climates, and are built in varying controlled environments.

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I don't think that many ukes are built in controlled environments, and don't expect that all from Asia built ones. I know that Kanile'a has climate controlled factory with a setting for compatibility with most of the mainland. But a cheap Indonesian built uke that I received in January started fret sprout within two weeks suggesting that it was built in a very humid environment. I now keep a little sponge below the neck in the gig bag which helps as my house is very dry (10%) in the winter.

Should I be humidifying all laminate ukes or a glossy cedar top with laminate sides and back here in dry Southern California? It’s a beautiful 70F but about 10% RH. I never have yet in over 5 years. Thanks for any input.

socal16 said:

Should I be humidifying all laminate ukes or a glossy cedar top with laminate sides and back here in dry Southern California? It’s a beautiful 70F but about 10% RH. I never have yet in over 5 years. Thanks for any input.

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If everything is fine for 5 years then definitely don't change anything. Laminate is resistant to humidity changes and the neck is likely well adjusted to its environment.

Try to keep the humidity levels fro 42-50% as much as possible. This is difficult to do in some parts of the country, but this is best. 30% is too low and 60% is too high. If the room is 45%, and this is where the ukes live most of the time, you don't need anything else. The moisture content in the wood should be at 5-7%, before the wood is used in construction. If it is higher or lower than this, it will be trouble down the road if the uke leaves the environment is was made.

Sorry if I missed an answer to my question in one of these posts, but my question concerns a house with high humidity during the summer. Today, with the air conditioner off and outside temps at high 70s, indoor humidity is at 55. Which is OK. But in a few weeks, with air running, my humidity commonly goes into the upper 60s, sometimes higher. I use humidifiers with my wood ukes during fall, winter and early spring but take them out when humidity spikes. So my question is what options are there to maintain and protect wood instruments when general humidity hits problematic areas?