1934 Gibson L-Century: severe damage from Planet Waves Humidipak

What a shame. I have in my shop the above guitar, in which a Humidipak dumped it's contents, causing  finish loss and severe swelling to the lower bout. The bare, warped wood is now saturated with whatever was in the Pak: it feels 'greasy' or slick: I'm pretty sure glue or finish won't adhere to the wood, as is. Anyone know exactly what is in these bombs? Anyone dealt with this problem of saturation(apart from the swelling and distortion)?

Secondly: the guitar will need a neck reset, and refret, and I'm aware those will be quite the task. Anyone had to do these repairs on this style guitar? How to heat the fingerboard extension, to separate it from the top? And a good procedure for a refret(there's almost no playwear, but the guitar literally sat in a closet for 60-plus years, and the frets are lifting).

Third: there is significant bellying behind the bridge, Yet some of that belly(or arch) seems original, because the bridge base appears tapered. Did these guitars indeed have a substantial arch, when new?

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What a nasty mess!   I had one a couple of years ago - a spruce/cypress flamenco that had been sitting on a stand with the humidifier leaking and dripping down to the end, much as this one had.  

Inside it was a sticky, mostly dried mess, almost black.   Outside, stains went through the wood where the top separated from the side, and black stain migrated up into the top.  I did what I could to clean up the inside, reaching way down in there, mopping with solvents - mostly acetone.

Simply no way to make it look good where the black had wicked up into the end grain of the top.

Boveda makes the Humidipaks for Daddario and I would contact them about what to do to clean this up. 

Should they balk, try to find out the make up of the humidipak. They make lots of different humidity control products and each one uses a different salt(s) and gel mixture as the control. Potassium Carbonate is the control for 43%RH at room temperature and is probably what is used in those packs. If that is what they used, it's a strong base and will need to be neutralized with an acid (white vinegar) to prevent further damage. This will convert it to Potassium Acetate and make it easier to remove from the wood.  Distilled water is the best solvent. It is not soluble in acetone and only mildly soluble in ethanol.

I would take a rag soaked in household white vinegar and apply liberally to the affected areas inside and outside and repeat until the fizzing stops. Follow with liberal application of distilled water soaked rags/dry rags until the soapy/greasy feeling goes away.

Thank both for your replies. Mark, that information and suggestions are very helpful. I have been waiting confirmation on the brand of 'humidipak' from the guitar owner(indeed it is Boveda/D'addario), and I will now contact them for additional info. I've never seen anything quite like this damage: the wood is so severely swollen,  I really wonder, even with a though cleaning with the correct 'antidote', if the swelling can be reversed.

Mark, I have heard back from Boveda, the maker of the D'Addario Pak. The contents of the Pak are Sodium Formate, Sodium Lactate, and Xanthan Gum. Can you say, if your suggestion for white vinegar and distilled water are appropriate for these substances?


Don't use vinegar (acids) with this mix. Warm water is the best option and I wouldn't expect much change in the color unfortunately. I would use repeated applications of warm distilled water in a dampened sponge to get it out of the wood.  After it's clean and dry, Oxyalic acid solution might be tried in an out of the way place to see if it will lighten the darkness.  You can get OA powder cheap on Ebay.


Just to add my two cents, I've seen this twice in the last year, both times in a Taylor. It's a HORRIBLE mess and pretty much stains the unprotected wood to some degree even after cleanup. I, like Frank, used acetone and got a lot of the mess out but the wood looked as though it had black pore filler rubbed into it.

I have recommended the Kyser Lifeguard for its ease of use and the fact that it only humidifies the guitar. It's not tasked with humidifying the case, and the guitar can sit on a stand or hang on the wall and be protected. I've never seen a problem with it in 3 decades of experience with it (this is not a commercial for Kyser and I have no financial interest). :)

The Kyser is ok but it requires care to squeeze it out thoroughly. I had one that I didn’t do that with and it leaked enough to cause a nice little lacquer bloom on the edge of the soundhole, just north of the bridge (The guitar was on a stand).  These days I have a whole house humidifier.    BTW, I much prefer the earlier version by Entex, the maker that Kyser bought out. More flexible and easier to get in and out as well as to squeeze dry. 


Acetone can help remove staining from bare wood.

to loosen the fretboard extension  heat your removal tool and apply water to the joint. Don’t heat the fretboard. Tapping a chisel at the fretboard end may help loosen it too.

another option is to heat the fretboard extension from inside the guitar.


Concerning the frets you may be able to reseat them and glue down with super glue. If the current fret height is less than .030” then I would replace them. 

Seems Gibson used really low fret wire in their history. I resently re-fretted a banner LG 2 that had a fret height of .025”, if I remember correctly, and the guitar came from the original owner and no fret wear at all. He played it from purchasing it new like a Dobro with a nut extension.


Thanks again for your replies. Personally, I would never use this type(or an Oasis type) humidifier, because of the potential for this kind of damage(I've used a 'Dampit' type , since 1975). Yet, large quantities of both are sold...

It appears to me, that the sodium compunds(and the xantham?) have permeated the wood of the damaged areas, and have caused those areas to remain distorted, even after any water has evaporated. Also, I would think the saturation of the wood will prevent adhesion of glue or finish for repair. The back will need to come off, to effectively mop out the compounds from the inside surfaces. I'll need to then make a two part form to clamp the distended side area back into shape.(and I'm not confident it can be clamped back into shape: or flat, for the back). And, I won't be sure I've drawn out all(or enough) of the offending substances, until I try glue or finish on them.

I'm beginning to think, it may be better to cut out the damaged areas on the side, and back, and patch in with new figured wood. That would not require removal of the back, the patches would be largely hidden by the almost opaque color of the sunburst(given a very good finish touch-up), and I'd know the adhesion problem would be moot. Side patches are a not uncommon repair.

Jim, your suggestion to heat the top(under the extension) seems good- I could maneuver a heated, shaped, metal block in, to contact that area.

I plan to use new, larger wire for the refret- the existing, original wire is indeed very small. I'll need a taller wire to level them.

Well, this kind of project is what makes repair work(in the end), so satisfying!



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