Rigid foam cases and humidity?

[dhanners623]

Here's a question: When it comes to maintaining relative humidity in a guitar, is a rigid foam case any better or worse than the standard run-of-the mill Gibson hardshell?

 

I've got both for my J-45. It came with the hardshell, but a couple of years ago, when I started going to more festivals and traveling more in the summer, I got a Gator lightweight case for it, too. It is much lighter than the wooden case but still provides very good protection. But a repairman told me that rigid foam cases suck the moisture out of the guitar, particularly here in Minnesota in the winter.

 

I humidify my guitar with a Kyser soundhole plug humidifier, as well as a sponge in a soap dish for the exterior of the guitar. The soap dish won't fit in the Gater case, though.

 

I'm wondering if anyone else out there has any thoughts or knowledge on this matter.

[BigKahune]

DH - That's news to me.

 

I hope someone with knowledge/experience responds. I'd like to see what they say.

 

I would suggest a gauge for the inside of the case to keep a handle on the humidity level. I've seen some posts about with over humidification problems when keeping the guitar and a humidifier in a closed case. It happen to me once years ago and fortunately the case was only closed for a couple weeks - no damage, just a bit of belly swelling.

[Buc McMaster]

But a repairman told me that rigid foam cases suck the moisture out of the guitar...

 

How is this possible? Those rigid foam cases are made of what amounts to thick styrofoam, yes? If they absorbed moisture at all how could we use them as coffee cups? I've never seen a styrofoam cup all mushy from floating in a lake or laying in a trash heap in the rain. This stuff, in my mind, is impervious to moisture. Consult another repairman......

[dhanners623]

Gator says the foam in the case is expanded polystyrene (EPS) so I don't know if there's something about it that would absorb moisture. I went to Gator's website and sent them a message asking the question, and I'll post the reply here when I hear it.

 

The repairman who told me this is a top-flight guy and knows his guitars; he works at a nationally-known shop (and Gibson dealer) in the Twin Cities. So I'm not discounting what he says. I'm just wondering if maybe he was thinking of semi-rigid cases (or even gig bags) made out of other material.

[TommyK]

I have to agree with Buc. Styrofoam doesn't have any affinity for water. So, to answer your question, the styrofoam shouldn't dry out your guitar any faster than any other material.

[devellis]

I would think the determining factor would be the tightness of the case seal rather than the material it's made of. Hard to imagine, as others said, how styrofoam could dehydrate a guitar.

[eds111]

I agree it is the seal that would let the moisture in. A hard shell case with the latches closed forms a pretty tight seal. I would at least store the guitar in the hard shell case in the winter. I always have hydrometers inside and outside the case, but I admit I am fairly obsessed with humidity...

[modoc_333]

here you go:

 

 

 

Water Absorption and Vapor Transmission

Moisture resistance is the ability of a packaging material to prevent water from entering its structure and eroding its mechanical properties. The cellular structure of Expanded Polystyrene is essentially water resistant and provides zero capillarity. However, Expanded Polystyrene may absorb moisture when it is completely immersed, due to the fine interstitial channels between the molded beads. While molded Expanded Polystyrene is nearly impervious to liquid water, it is moderately permeable to water vapor under pressure differentials. Vapor permeability is determined by both density and thickness. Generally, neither water nor water vapors affect the mechanical properties of Expanded Polystyrene. See Table 3.

 

http://www.texasfoam.com/table3.htm

 

from the website:

 

http://www.texasfoam.com/technical-data.htm

[Mizdeb1948]

This last comment was clear as mud to me and the links are broken. Is he saying yes, it absorbs moisture, or no unless you put it in a pressure cooker?