Why do PRS Guitars Need 40% Humidity?

[AlastairLC]

If the wood in PRS guitars is dried to 6%, why do they need to be kept at 40%+ humidity? This makes no sense to me. We don’t do this for fine furniture. I think abrupt changes in humidity would do more harm and this would happen when taking the guitar out of a high humidity storage area to a low humidity gig. What am I missing here?

 

[Prs Mods too]

Welcome to the nuthouse!

Never heard of that. I keep all of my instruments around 50% relative humidity and have never had any problems even gigging in 30-90% RH environments.

Maybe if you use a gig bag or break your guitar out 10 hours before the first set your relief might change. If you like super low action you might end up with some notes choking out.

I've always left mine in the hardshell case until soundcheck and have never had any problems and I'm a lowest of low action guy. Nothing but 4 hour gigs for this kid too.

Curious where you heard the 40% RH thing. Is it concerning acoustic guitars, because I don't really know much about those.

 

[dmatthews]

Cuz it's better than 39%?

 

[RickP]

I live on the Gulf of Mexico coast, and have gigged my PRS guitars at outdoor festivals and the like here for many years with no issue at all. I wouldn’t worry over that number, as double or more that isn’t uncommon here.

 

[Abe]

I have mostly concerned myself with my Acoustic guitars, especially my Taylor. Second to that I'd guess that Hollowbody and Semi-Hollowbody Electrics would be of more concern than solidbody electrics. Still wise I think to avoid anything drastic in the highs and lows of humidity.

 

[dmatthews]

I live on the Gulf of Mexico coast, and have gigged my PRS guitars at outdoor festivals and the like here for many years with no issue at all. I wouldn’t worry over that number, as double or more that isn’t uncommon here.

I live in Vancouver Canada, and have never needed to care.
All good.

 

[Moondog Wily]

@Abe had posted in another thread, this from PRS:

Do not expose your PRS instrument to prolonged extreme temperatures or humidity as it could be damaging to the instrument. We have found the optimal temperature to be between 70 and 74°F with a humidity level between 40%- 45%.

But in reading that, it says that the 40-45% is "optimal". That does not say to me that it must be stored at 40%. And as others have brought up, both here and in other threads, the more acoustic a guitar is, the more you have to worry about the humidity levels in part because of the exposed woods that have no finishing whatsoever to protect them. The humidity is going to get into those unsealed wood surfaces WAY faster than finished areas. And of course what it is finished with and how thick that finish is will also effect how much protection a guitar has from the humidity levels. With solid body electrics. very few places for humidity to get into the wood without going through some finish first. The pup cavities are one of those places it can often get to the unfinished wood. Bolt on necks is another place where you may have some unfinished wood. And then of course, the cavity through which the electronics run connection. There are unfinished necks, which would be more prone to humidity effects and most fretboards are not "finished", so ones of that type are going to be more "open" to effects from humidity. Other than that, a solid body electric is pretty tight! So, 40% is a recommendation, the key message here IMO is "Do not expose your PRS instrument to prolonged extreme temperatures or humidity as it could be damaging to the instrument.". And if it is an acoustic, your concerns are increased by many factors not only due to the unfinished woods, but the much more fragile thicknesses of the woods used in an acoustic guitar body, so humidity can get in deep real quick!

 

[Abe]

Currently 'I think' I'll be okay with this hollowbody hanging on the wall where the humidity does sometimes go down to 30% due to the air conditioner. The driest in the winter likely about the same but I'll watch it. But it isn't at that 30% all day, and for many of the hours it is 40% so 'I think' I should be fine.

 

[Black Plaid]

So, here's the thing, humidity is relative to the medium and temparature it is in. 40% for air at 70F is likely closer to 6% for wood at the same temp.

Also, their factory is apparently at about 40%, or so I hear.

 

[Moondog Wily]

Currently 'I think' I'll be okay with this hollowbody hanging on the wall where the humidity does sometimes go down to 30% due to the air conditioner. The driest in the winter likely about the same but I'll watch it. But it isn't at that 30% all day, and for many of the hours it is 40% so 'I think' I should be fine.

You could use some Boveda de/humidity packs in the f-holes of your HB while it is on the wall. They add humidity when below a certain point and remove humidity when above a certain point. They make a "saddlebag" like holder for 2 packs that you can saddle over the strings at the soundhold for a regular acoustic, but you could fashion something to hold them inside of the body of your HB while it is on the wall if you are concerned about the levels. Just a thought ;~))

 

[László]

You could use some Boveda de/humidity packs in the f-holes of your HB while it is on the wall. They add humidity when below a certain point and remove humidity when above a certain point. They make a "saddlebag" like holder for 2 packs that you can saddle over the strings at the soundhold for a regular acoustic, but you could fashion something to hold them inside of the body of your HB while it is on the wall if you are concerned about the levels. Just a thought ;~))

I use those packs in my cases, including the electric guitars. Since I started using them, I haven't needed a single adjustment to any guitar, including guitars I've had for ten years. Great call. Except...

I'm not sure how well they'd work in a guitar hanging on the wall - maybe better than nothing, maybe not. My feeling is that unless the packs are in a fully enclosed space like a case, they're not going to regulate the humidity in the way they're designed to do. Most of it will escape through the f-holes. And they won't have any effect on humidity changes in the area of the neck and fretboard, where big problems often show up (neck bow, twisting, fret sprout, etc).

They work in guitar cases that are completely closed. If I was to hang my guitars, I'd choose a room humidifier. Just me. YMMV.

 

[Abe]

I have a digital hygrometer a couple feet away from my hanging hollowbody guitar. It has dipped down to 30% at times relatively briefly because of the air conditioner working hard against the heat, but for the most part it's 40% or so. Currently at 47% with the recent tracked lows and highs being 42% and 48%.

Also I'm kinda thinking that this SE guitar being laminate, it wouldn't be as prone to damage at least in it's body. Rising frets from the ebony fretboard I would guess to be of more concern with this particular guitar. If I see it staying at 30% for an extended time period and I'm not busy playing it I will put it in it's case and consider humidity packs.

 

[archtop]

You're neck relief will go wonky when humidity drops below 15% and especially below 10% you will start to experience 'fret sprout' where the fret ends start to stick out due to the fingerboard drying out. Acoustic guitars with spruce tops can experience cracks in the top, the top bowing in, separation of bracing and bridge plates, etc. When living in the desert Southwest I even saw an ebony fingerboard shrink at a different rate than the maple neck which caused the fingerboard to separate at the widest point of the fingerboard.

 

[Abe]

I think the neck relief going to crap is what happened to an old Ibanez Nylon String Acoustic some years ago when the house I lived in was heated by firewood. It had no truss rod to adjust, and it just went to displeasing dead spots around the fretboard making the guitar pretty useless even though it was decent when new.

 

[bodia]

If the wood in PRS guitars is dried to 6%, why do they need to be kept at 40%+ humidity? This makes no sense to me. We don’t do this for fine furniture. I think abrupt changes in humidity would do more harm and this would happen when taking the guitar out of a high humidity storage area to a low humidity gig. What am I missing here?

It's not just PRS, it's all guitars.

 

[RC Mike]

I use those packs in my cases, including the electric guitars. Since I started using them, I haven't needed a single adjustment to any guitar, including guitars I've had for ten years. Great call. Except...

I'm not sure how well they'd work in a guitar hanging on the wall - maybe better than nothing, maybe not. My feeling is that unless the packs are in a fully enclosed space like a case, they're not going to regulate the humidity in the way they're designed to do. Most of it will escape through the f-holes. And they won't have any effect on humidity changes in the area of the neck and fretboard, where big problems often show up (neck bow, twisting, fret sprout, etc).

They work in guitar cases that are completely closed. If I was to hang my guitars, I'd choose a room humidifier. Just me. YMMV.

This is correct. The packs won't do much unless in a case. I've seen some acoustic guitar humidifiers that are intended to seal the sound hole, which might have a different result.

I keep my acoustic and hollowbodies cased year-round. The unfinished wood breathes quite readily, and I have no desire to get a crack because I didn't take simple steps to protect the guitar. It does mean that I don't play them as often as the solid bodies that hang on the wall.

Here in Minnesota, we end up with all sorts of damp and dry. Especially in basements, where most of my guitars are. I run a dehumidifier about 9 months of the year. Winter can get quite dry. I've got a whole-house humidifier, but won't generally use it. Condensation on windows in the winter is a sure what to get both rot and mold.

I use Arion in-case humidifiers year-round. It's an aero-gel that is super easy to use. Cheaper than the humidipacks in that it's completely reusable. I wasn't happy with the sponge and tube type humidifiers--too much can go wrong there. The humidipacks always seemed too short-lived for my tastes and I didn't have much luck reviving any of them. I don't have ask much to think about with the Arions. They just do what I need them to do.

 

[GGJJGG]

I use those packs in my cases, including the electric guitars. Since I started using them, I haven't needed a single adjustment to any guitar, including guitars I've had for ten years. Great call. Except...

I'm not sure how well they'd work in a guitar hanging on the wall - maybe better than nothing, maybe not. My feeling is that unless the packs are in a fully enclosed space like a case, they're not going to regulate the humidity in the way they're designed to do. Most of it will escape through the f-holes. And they won't have any effect on humidity changes in the area of the neck and fretboard, where big problems often show up (neck bow, twisting, fret sprout, etc).

They work in guitar cases that are completely closed. If I was to hang my guitars, I'd choose a room humidifier. Just me. YMMV.

I have one in my SSH case. Should I have them in my DGT and MEV? Dare I use one in my 1985 Les Paul case?

 

[Moondog Wily]

I have one in my SSH case. Should I have them in my DGT and MEV? Dare I use one in my 1985 Les Paul case?

I have the Boveda packs in all of my guitar cases, electrics, acoustics and hollowbodies! Regardless of the guitar type, a proper humidity level is good for the wood ;~))

 

[Argus_Floyd]

I use those packs in my cases, including the electric guitars. Since I started using them, I haven't needed a single adjustment to any guitar, including guitars I've had for ten years. Great call. Except...

I'm not sure how well they'd work in a guitar hanging on the wall - maybe better than nothing, maybe not. My feeling is that unless the packs are in a fully enclosed space like a case, they're not going to regulate the humidity in the way they're designed to do. Most of it will escape through the f-holes. And they won't have any effect on humidity changes in the area of the neck and fretboard, where big problems often show up (neck bow, twisting, fret sprout, etc).

They work in guitar cases that are completely closed. If I was to hang my guitars, I'd choose a room humidifier. Just me. YMMV.

A minimum of 40% humidity is recommended for all guitars. It's not just a PRS thing. The people replying saying they never worried about it, never had a problem, etc. are just unaware that they've been lucky that the humidity has stayed above 40% for however they've been storing them. I've got a friend whose acoustic guitar's bridge came unglued and completely dettached from the guitar because he stored it sitting up aginst an outer wall of a room during winter.

 

[Abe]

How much fluctuation, how brief or prolonged the time periods of non-ideal humidity %, and the average humidity it stays at must be very relevant to what constitutes the danger zone for the guitar.