Principles of case humidification

[David Eastwood]

Originally Posted by FrankHudson

I use this one. There are others in their line, but these are reasonably affordable.

Govee H5179 wi fi Thermo-Hydrometer

Thank you! Much appreciated.

[ljguitar]

Originally Posted by ethanay

…4. Sealed cases
These are non-breathable, ultra-insulated and they even often have rubber gaskets around their opening to completely seal the inside from the outside. These cases, although typically more expensive, are also much easier to work with in dry conditions because a. they don't absorb nearly as much in the way of moisture and b. they aren't permeable, so the humidity stays put until you open the case. As a result, a bit less humidification capacity is needed to maintain the relative humidity in the case and guitar.

Hi etahnay…
I'm going to elaborate on 'sealed' cases.

I own a variety of hard cases including a pair of Calton cases for guitars, and a large number of completely air-tight camera cases. They are quite different in construction and function.

Better carbon fiber guitar cases would fit into the category I lifted your quote from (above). I'd like to offer some suggested corrections and considerations.

• Most are not air tight, nor sealed from moisture exchange.
• They do breathe (a good thing). In other words, they are permeable.
• Their interior will absorb as much moisture as other cases if they are lined with wood and covered with carbon fiber…albeit at a slower rate.
• I end up 'charging' the internal humidifiers just as often as in my non-carbon fiber Cedar Creek and other wooden-shell based cases.

I'll add the following observations and conjecture…

• If instrument cases did not breathe, mold could/would become an issue (depending on the climate zone one lives in).
• If they did not breathe, they would need an air exchange release valve.
• In a short 5 hour drive from our home to a city 300 miles (485km), I have to release the air release valves on my camera cases to even get them open, because the elevation has changed from 6,350 feet above sea level (1,935 meters) to 2,150 ft (655 meters).

I own 4 air-tight camera cases and all of them have air release valves. I was aboard a flight several years back and we were at 30,000 feet and I had my camera out shooting pictures of some mountains and clouds during the flight. The pilot announced we were landing, and my camera case would not open being sucked slightly concave from the change in air pressure between sea level and 30,000 feet.

I quickly pulled out a coin and removed the air release valve, and the case began sucking in cabin air (whistling)…which it did for the next 10 minutes (with a cabin crew member standing over me in the aisle repeating "please' open the case and put the camera away"). About 10 minutes later when the air equalized enough to pop the lid - I put the camera away much to the relief of myself and one nervous flight attendant.

We do not humidify cameras, specifically so we don't end up with mold and or dust invading the mechanisms, sensors and lenses. In fact, we want them totally isolated from the elements except when shooting in extreme cold or humidity, in which case we want them acclimated before we begin to shoot so the lenses don't fog up with condensation.

Guitars, wooden clarinets, flutes, orchestral instruments all need protection, but not mold. So the better instrument cases have tight fitting, yet breathable seals.

There may be totally air-sealed instrument cases built (with pressure relief valves), but I've not seen any.

There was a forum member (years ago) who as a novice had put his guitars in a garbage bag and sealed it up with a case humidifier inside the bag while on an extended trip, who returned home from his trip to a guitar with mold both inside and outside of it.

I have friends who lived in a tropical environment (in a jungle) for several years, who bought carbon fiber guitars because their traditionally built guitars battled insect infestation, mold and glue turning loose on bindings, and bridges.

More than one forum members over the years who live in Hong Kong (and similar locations) have constructed de-humidifier cabinets (mechanically removing moisture) to keep the humidity levels beneath 90% on their quality instruments. Their guitars hang in a dehumidifier 'closet' during the most extreme conditions.

Hope this adds to the discussion…

[dilver]

I’m fortunate to be able keep the majority of my guitars in a relatively small 12’ x 12’ closed room with a room humidifier. All guitars are on wall hangers and I’m able to control and maintain humidity and temperature fairly easily, by keeping the door closed and keeping the humidifier filled. With a large number of instruments, I think it’s more practical than having individual case humidifiers. I know there are people who are for and against wall hangers, but in 20 years I have yet to encounter any issues due to lack of humidity, with both new and vintage acoustics and electrics.

[jmjohnson]

/\ /\This. I'm with you, dilver, wall hangers and all.

[dwalton]

I don't have a thesis to offer on this topic - only direct experience over several years in a very dry (winter) environment. This assumes a decently tight case that will retain most moisture.

Buy the D'Addario Humidipak kit - three 49% humidification packs, a 2-pack holder for the soundhole, and a 1-pack cover for laying in the headstock part of the case. Also buy a 10-pack of Boveda 49% replacement humidifier packs, 70 gram size.

Install the 2-pack in your guitar's soundhole (hanging from the A and B strings so they don't touch the inside). Lay the single remaining pack in the headstock area of the case. If you want, throw an extra pack into the headstock area.

Store the guitar in the latched case when not in use. Humidity will be fine. You may need to tweak a truss rod but that's expected. When a pack(s) dries out (maybe after a month?), replace it, reuse the dried-out packs if you want, and if not toss them.

This has worked for years for me with my Collings (TKL case) and also my classical. Zero issues.

[rokdog49]

The year around humidity levels in my house are 40-50%.
I don’t do anything…

[ethanay]

Originally Posted by ljguitar

Hi etahnay…
I'm going to elaborate on 'sealed' cases.

[...snip...]

Hope this adds to the discussion…

Yes, it does, thank you! I didn't mean completely air tight, but definitely a much lower rate of vapor and air exchange for fiberglass cases with gaskets. I had recently tried a pretty nice guitar that came with a $$$$ Visesnut case, and when it arrived it had a slight vacuum seal to it and was a little difficult to open.


A sealed case isn't a problem, intrinsically, as long as internal RH is ~40-50% (mold and mildew start to become a concern above 50% RH is my understanding, in which case airflow is necessary) but I think something missing from the discussion is: A sealed case is much easier to overhumidify, whether it's a gig bag in a trash bag or a nicer case with a negligibly small air exchange rate.


Do we sound like we are closing in on a shared understanding?

Originally Posted by dilver

I’m fortunate to be able keep the majority of my guitars in a relatively small 12’ x 12’ closed room with a room humidifier. All guitars are on wall hangers and I’m able to control and maintain humidity and temperature fairly easily, by keeping the door closed and keeping the humidifier filled. With a large number of instruments, I think it’s more practical than having individual case humidifiers. I know there are people who are for and against wall hangers, but in 20 years I have yet to encounter any issues due to lack of humidity, with both new and vintage acoustics and electrics.

Do you use a wicking humidifier, a hot vapour humidifier or an ultrasonic with distilled water (to avoid the mineral dust)? Do you keep them out even when you are not at the house?



One of my major concerns about that is if there's a power outage and I'm away, the whole thing can go to **** really quickly with temperature AND humidity swings. I'd want case humidification AT LEAST as a backup. To me it's not a problem to take instruments out in the morning and put them away at night or when I'm away from the house. I find that's a good compromise.


I will say that pretty functional DIY room humidifiers are relatively easy and cheap to make out of any sort of absorbent towel to use as a wick, something to hold the water and dip the wick (can be a simple bowl), and a fan or box heater (nice in the winter and a bit more effective at increasing humidity). After having done quite a bit of research on room humidifiers I think that's the route I'd go. No dust, no consumables, no distilled water, and about as modular and serviceable as it gets.

[The Watchman]

ethanay, just a note that boiling water doesn't precipitate minerals (unless you boil all the water away), it concentrates the minerals and dissolved solids. Just not enough to worry about in this context.

[Gas]

I use whole home humidifier and Govee humidistats. Two of my guitars in the case