Guitars and Humidity

[fws6]

Serious answer, I live in a dry area too. Or at least, in winter it is. So I have a hygrometer , and as soon as values are dropping my guitars are in a locked display cabinet, with humidifiers

as I do like to take them out and play during winter as well I also have a humidifier in the room. I have Venta lw45 machines with which I am very happy. Others on this forum were less enthousiast so depends a bit on what you want or where you live / quality of your tap water

since you say that you are often away for longer periods , you might want to look at a case humidifier system that lasts a couple of months.

if dont want to store the in the case, it should also be possible to combine such a case hydration system with a small / lockable display case.

and finally , re-hydration certainly is possible. My luthier does a lot of crack repairs, but he always keeps the guitar for 3-4 weeks in his well hydrated shop before doing the repair, so the guitar is rehydrating in its own tempo before attempting the repair

[Patrick2]

All good advice. . except of course the soaking it in a bath tub part. But, important to remember, introduce the rehydration gradually not all at once. That's how the guitar would have dried out . . gradually. Rehydrate it the same way.

The last sentence in fws6's [more serious] post says exactly that.

[fws6]

Sorry about that

hard to resist though

[peskypesky]

[geoffsct]

Thanks fws6 that's good news. I'll start rehumidifying and get the Humicase stuff for when I'm gone.

[ingeneri]

I use humidipaks in the case as I have to ship several guitars internationally every few years and it can take 3-4 months on the boat. Cheaper option than the humidified case (especially since my 18" Super Eagle would need a custom sized case).

[Woody Sound]

Aprilair home humidifiers tie into your heating system. (If you have air heat.). Pricier than standalone devices, but not obscenely.

[Patrick2]

I use humidipaks in the case as I have to ship several guitars internationally every few years and it can take 3-4 months on the boat. Cheaper option than the humidified case (especially since my 18" Super Eagle would need a custom sized case).

Where do you usually store the humidipaks? Are they in the case pocket? The void area between the case pocket and the neck heel? Do you actually put them inside the guitar? Also . . 3 to 4 months on a boat? Wow. Do the humidipaks remain hydrated that long?

[Woody Sound]

[jazzbow]

All sound information, I like the cabinet idea, especially for a valuable instrument that deserves to be seen. Otherwise the case hydrator is sound too.

re-hydration certainly is possible. My luthier does a lot of crack repairs, but he always keeps the guitar for 3-4 weeks in his well hydrated shop before doing the repair, so the guitar is rehydrating in its own tempo before attempting the repair

Re-hydration through osmosis, do-able with solid woods, laminate woods however offer us a challenge:

Ibanez electro acoustic, laminated, restored for sentimental reasons as repair cost was more than value.


Bellying and partial bridge lift.


Drastic action for instant re-action, steam iron set to steam through sound hole


Heavy tool box used as weight to press down belly until flat and dry inside body


Rosewood dust and glue mix, a bridge reset on a painted laminate guitar is a bridge too far IMO (jazzbow knees)


Flatter top and better contact for bridge


So we went from this....


To this (there was bridge and saddle work too)


Finished :-)

[ingeneri]

Where do you usually store the humidipaks? Are they in the case pocket? The void area between the case pocket and the neck heel? Do you actually put them inside the guitar? Also . . 3 to 4 months on a boat? Wow. Do the humidipaks remain hydrated that long?

Patrick, one goes under the guitar's head while the other lays on the lower bout (they're sealed in paper packets and then go inside a cloth casing.

Since the boats have been between DC and SE Asia, lack of humidity has not been the major issue. Part of the appeal of the humidipaks is they work two-ways and can act as a controlled dessicant as well. I'm using them for humidity right now, and keeping the SE snug in its case while my 525 and Vestax D'angelico take up the load.

I try to baby the Super Eagle even though I insist on gigging with it and it's gotten plenty of dings over the years. But a freind plays his Eastman 365 days a year without problems despite the winter cold and humidity drop.

My big guitar that got away was a 1953 ES-175 before the prices increased 25%. I chickened out because I was afraid I'd kill the guitar taking it with me when I was moving to China a decade ago. The salesman at Sam Ash in NY tried to convince me Guangzhou's swampy humidity would actually do the Gibbie good, but I was too anxious to listen. Stupid, it would have been a great player. He who hesitates is lost!

[stringsalive]

You can rehydrate, but never enough to return 100% of the original size. I don't know why this scientifically, perhaps someone with more knowledge in that field could answer that. In Lutherie, a general rule of thumb is rehydrating will only return about 50% of what was lost. Rehydrating a guitar with a crack from drying is standard, and with some you can get it close enough to repair with just glue; most, however, require wood to be added (in the most disguised manner possible) to the gap - which also helps to prevent future shrinking issues - because it will never quite close on its own.

[mr quick]

I'll be moving out this week and the apartment might get a bit more dry than my current setup. I don't have any solid-top guitars, does it even matter?

[ptchristopher3]

no responses huh?

Should have asked about "intonation", that would have gotten a variety of responses,...

Anyway, in my opinion,...:

Humidity does matter, but to a far lesser degree once you get away from solid woods in thin dimensions with modest bracing.

So in short you will likely have limited troubles if your guitars have no solid backs or tops. But,...

Wood has three dimensions. OK, no news there.

They are described as longitudinal, radial, and tangential.

Longitudinal is from the ground to the sky in the tree, and wood moves very little in this axis with humidity changes. But it does move some and, this axis has significant consequences for a neck.

Radial is from the core of the tree out to the bark. This ends up being across the top of your solid topped guitar.

Tangential is perpendicular to radial and ends up as the short dimension through the top of your guitar - so something like 3 mm through the thickness of the top of a guitar.

The trouble with humidity changes is that under VERY dry conditons the wood wood shrinks along the radial and tangential axes FAR more than the longitudinal axis. This can result in tension and eventual splits along the grain from shrinkage along the radial axis in a solid topped guitar.

It can also lead to exposed fret ends due to shrinkage along the radial and tangential axes in a neck and FB. This also can give you split FB bindings as the frets protrude into the abs plastic. So there is some trouble for your non-solid top guitar.

One aspect of timber that is of great concern to the general wood industry is the differential between radial and tangential changes with humidity. This leads to cup and curl in slab cut wood. This can be a problem in some solid body guitars, and slab cut backs and sides, but not often.

And,...

While limited, the changes along the longitudinal axis in your FB and neck will often be different from each other. Ebony FB wood changes more than Rosewood, and notably more than most neck woods such as maple and mahogany. So as the guitar dries out expect to see more neck relief and the need for truss rod adjustments. Notably more with ebony than rosewood FB's.

Sooooooo,...

In my opinion you will be fine, but not entirely without consequence.

If your fret ends protrude, get this fixed in the dead of the dry season where you live (which is about 20 minutes from now in the northeast USA). This will allow your luthiator to get the fret ends at their worst - when the neck wood is at is most shrunk-ed-nest.

Good luck with this and your move.

Chris

[wintermoon]

It matters especially if it's a drastic change in humidity.
Also seeing as how you're in Norway I imagine it's cold and the air is dry from the home heaters.

Makes more of a difference with acoustic/solid wood guitars, but even solid bodies can contract "fret sprout" etc
Buy a hygrometer and monitor the humidity.

ps looks like I was typing while pt was posting

[va3ux]

Getting a good hygrometer that reads fairly accurately is not easy. There are hundreds of hygrometers on the market and many of them a real junk. They'll provide a reading; it just won't likely be accurate.

If you're going to buy a hygrometer and since you're in EU, get one from Fischer or Lufft in Germany. If the RH reads under 40% at room temperature, either humidify the air space or humidify the guitar case (with the guitar in it of course).

Heating systems do not 'dry out the air'. In winter the cold air outside the house has less moisture than it does during warm weather. The heating system in the house simply raises the temperature of the air but does not change the moisture content of the air. For a given moisture content ('humidity ratio'), the RH drops as temperature increases, and visa versa. But the actual moisture content remains the same.

[Jabberwocky]

Shrinkage...gotta keep an eye out for shrinkage.

[oldane]

Still living in Bergen, Norway? In that case I wouldn't worry too much. The air very rarely gets very dry there - to say the least. I live in Denmark where the climate is not too different from yours. In theory central heating could give too dry air in the winter, but despite that, I haven't through 40 years had any dryness problems apart from the protruding frets PTChris mentioned above on one new guitar which was built over a summer (in Maine, US). I filed down and rerounded the fret ends myself in the first winter I had the guitar and haven't had any problems since. I have always lived in central heated houses but have never experienced wood cracks or warps, though I do make minor adjustments of the truss rods of a some of my guitars twice a year.

BTW, the risk of those seasonally protruding fret ends is why I strongly dislike fret nibs. With no nibs, the job to fix them takes less than an hour even for an amateur like me. With nibs, the result will be cracked binding and will call for a bit more surgery which is beyond what I can do on my kitchen table. I still have to be convinced of the practical benefits of nibs from the players perspective, though I know some folks want them (because Gibson did/does them?). Maybe we should insist on having our guitars built during the winter if there's to be nibs. But I'm digressing.....

[Woody Sound]

I had an ebony fretboard split because of low-h. Ebony is particularly sensitive to h.

[DanielleOM]

One luthier pointed out to me each time your fretboard expands and contracts, your frets move, and they may not go back to where they were. Fret releveling is often required for this reason and not just wear and tear.

[Max405]

Marwin,
I think the proper humidity (around 40%) is very important. The wood shrinks and swells as it dries and takes on moisture. That kind of movement under a coat of lacquer is not good for your guitar. It impacts the binding, the glue joints and the lacquer itself in a slowly but surely, negative way. I probably go overboard when trying to control moisture in my guitar room, but I think its well worth the effort. The guitar deserves it.
Joe D

[Matt Cushman]

A guitar case humidifier is a good idea when you are on the move. If you have a case for your guitar add a small open ended container to hold a small sponge dampened with water. Most cases have a small accessory compartment that the container can be safely placed in.

[Runepune]

Get a good (at least decent) hygrometer. Check the calibration with moistured salt. I wouldn't worry much unless you're into extremes. I've never ever had any problems with my guitars (lots of acoustic ones too). Though I've always lived pretty close to the sea. The hygrometer has shown between 40-45% Rh all through this Norwegian winter

[michael_bxl]

Hi,

Every year or so, I find myself googling about humidity and guitar.

There is one thing I am worried about : the numbers tells : between Y % and X % humidity (relative humidity). But what about absolute humidity ?

Here is 2 exemples :
A/ 7 g of water/m3 -> 35°C -> 20% humidity
B/ 7 g of water/m3 -> 19°C -> 50% humidity

in this situation, there is the same amount of water in the air (7g), but the % are different. Is the A/ situation really drier (and so problematic for our guitars) than the B/ ?

Thanks

[sgcim]

I recently showed my archtop to a luthier about a minor problem I was having.
He looked at it for a second, and said it needed a neck set.
I asked him why, and he said because the action is higher above the 15th fret than it is on the first fret.
I told him I thought that was normal.
He disagreed, and said it was because I used very high gauge strings like most jazz guitarists.
I told him I only use TI Bebop 11s.
He said, 'Well, then it's because of the humidity' (I'm in NY).
I told him I use an Oasis humidifier in my case all the time.
He said I have to buy a large humidifier, and keep the guitar with it constantly on in a small room.

I phoned the luthier who made the guitar about this,( and who has done all the work on it), and he said the guitar didn't need a neck set.
Does the Oasis humidifier work that poorly, that it could cause a problem like this?