Active corrosion affecting Les Paul

[Mick Bailey]

A customer dropped off an older Les Paul with a few problems; the pot spindles and pickup selector had seized and the output jack was lined with green corrosion. The screws had grown into the woodwork with rust, and there are general signs of creeping corrosion where the bridge and tailpiece ferrules are inserted into the body. There are signs of corrosion on the pickup covers too. The pot covers are badly affected and look like they've come out of the sea.

The general finish is quite worn and the gold top finish is extensively cracked. The guitar is kept in a Gibson case.

I suspected that the case was holding moisture and I left a hygrometer inside for 48 hours and it shows that the humidity inside the case is much higher than outside. The history of the guitar is that the pots and switch have previously been cleaned and freed off, but after a while in the case it seizes up again. The guitar gets some studio use, but isn't gigged so spends a lot of time cased.

So, it leaves a couple of possibilities; either the case is wicking or holding moisture from the atmosphere and not releasing it when the air is drier, or the guitar itself has been excessively damp and has absorbed moisture through the cracks and missing finish, and it isn't drying out in the case. The rusted screws and ferrules make me think it's the timber that's too damp.

I've fixed the mechanical problems, but it's the longer-term I'm more concerned about.

My thought was to initially leave the guitar out of its case and get some free air circulation and see how it goes. There's certainly an active corrosion process happening that needs monitoring and arresting so that the value and playability of the instrument are maintained.

Has anyone else had practical experience of dealing with this situation and coming up with a permanent cure?

[Leo_Gnardo]

Has anyone else had practical experience of dealing with this situation and coming up with a permanent cure?

Clearly that LP needs a new case, and it's storage situation needs to be changed. Some people - leave their beloved axe in the boot (trunk for us 'mericans) or damp basement, cellar, etc. It's going to be just about impossible to fix the damage dampness has already caused to the guitars metal parts. The pickups are still working: good. I'd replace the tuners, pots, switch, wiring & output jack & hope the owner can develop the habit of storing it dry from now on.

Some people love that ming vase funky crackled finish look. I'd say leave it alone as a badge of its history. Of course the owner may choose to refinish. Whatever he wants, OK with me.

I'm sure more answers will follow. I'll get out of the way now.

[Mick Bailey]

I agree with leaving the finish alone and the owner likes it just the way it is. The reason I mention it is because of the increased surface area through which moisture could be absorbed. It may be that a guitar with a modern finish wouldn't be so badly affected. The pickups are a concern - if the metalwork is getting corroded, then it's only a matter of time before the pickups fail.

The owner is a pro who really looks after his gear and considers that his guitar is stored in dry conditions. I'm going to recommend he gets a thermo-hygrometer with max-min functions for when it gets cased-up. His other guitars are unaffected.

We've just had the wettest winter on record so that won't help much with atmospheric moisture.

[Chuck H]

Does that guitar have any bona fide provenance to guarantee it's not a flood survivor???

Take the guitar apart. Completely! I know it's a PITA to reassemble so it all depends on how far folks are willing to go. Let the guitar stand OUT OF THAT CASE for a couple of weeks. A month would be better. Then correct any neck problems that might have arisen from the wood drying out after being soaking wet. Reassemble it with any new parts needed for repair.

Get a new case.

Inquire as to where this guitar is stored. "At my house" isn't enough info. Where in the house? Where IS the house? Is there a mold or mildew problem in the house? Is there ANY reason the humidity in the house might be higher than normal?

Fix the guitar and ID the problem. It's clearly not a common one.

[Leo_Gnardo]

I agree with leaving the finish alone and the owner likes it just the way it is. The reason I mention it is because of the increased surface area through which moisture could be absorbed. It may be that a guitar with a modern finish wouldn't be so badly affected. The pickups are a concern - if the metalwork is getting corroded, then it's only a matter of time before the pickups fail.

The owner is a pro who really looks after his gear and considers that his guitar is stored in dry conditions. I'm going to recommend he gets a thermo-hygrometer with max-min functions for when it gets cased-up. His other guitars are unaffected.

We've just had the wettest winter on record so that won't help much with atmospheric moisture.

If the guitar is kept dry from now on, less worry about increased surface area. Pickups - he likes 'em, play 'em 'til they fail. Once sufficiently dried out, might opt to wax-dip to stabilize them and who knows, we might all be in the old folks home before having to worry.

I had to look after a herd of guitars on tour, and it was informative to keep a thermo-hygrometer in one of the guitar trunks just to know what conditions they had experienced in transit. Temp topped out at 137F after unpacking one January in Hawaii: the trunks probably had been left to sit in the tropical sun. Ten more degrees and hide-glued neck joints would have started coming unstuck, wax would have started draining from wax-potted pickups. Highest ambient was 117F at a tennis-court gig in southern California. It was a dry heat that day, not uncomfortable: 11% RH. Only once did I have noticeable damage: December 1995, after -40F in a Minnesota-bound trailer, plus 5 hours of "annealing" to room temp @ 55F in the St. Paul hockey arena, one Guild acoustic finish crazed as I watched it, with an eerie sound effect of super hi pitch squeeking noises. The Taylor acoustics: no problem at all.

It may take weeks or even months to thoroughly dry your client's Gibson to an acceptable level. One trick Taylor suggested was to place the guitar on a stand and fan air at it in a dry room. Water stuck deep inside that mahogany body is going to take ages to leave, so get started ASAP. There are wood-moisture-content meters. I don't know how much they cost but probably not cheap as a thermo-hygrometer. One of my clients who is a professional top quality restoration carpenter has one & says it's one of his most important tools.

One thing you'll be able to tell right away, exactly how "dry" your client's storage area really is. Maybe not dripping wet like the inside of a cave, but likely too damp to really qualify as dry for the guitars. 60% RH tops, down to 40% would be an ideal range.

- - - - edit - - - - added -

Chuck, one of my old geetar acquaintances Vinny Martucci lived (and maybe still does) on a houseboat at Verplanck, near the north end of Haverstraw Bay on the Hudson River . Damp, you bet! But never a complaint about soakin' wet guitars, as one might expect. Also Dave Gilmour's "home" studio for some years - on a houseboat afloat on upper reaches of the Thames. Can't be too bad. Hope he, Phil Taylor, all the gear & everything else have been staying dry too during this wettest of British winters.

Now it might take a close inspection of the instrument in question. H'm hand me the magnifying glass, it says here - "Gibson Canoe Paddle Mfg. Ltd." Hmph! Harrumph!

[Chuck H]

Great info and story.

FWIW the humidity on a houseboat should be relatively acceptable (provided it's floating). But the humidity in a house that is drinking water up from the ground and dispersing it in a closed space could be significant and detrimental. That's why I asked about mold or mildew. Fringe benefits of a life in the finishing industries.

A moisture meter typically used in the painting industry has two hardened steel prongs on a single end to place the distance between them predictably for the circuits calculation. They really only read the moisture content as deep as you can stab them. But this is still a good tool. Wood does have a way of evening out the moisture throughout it's mass. These meters can be purchased at hardware and paint stores for between forty and seventy bucks. It's the same meter in most places. Only the price fluctuates.

It seems the on line price is lower (if you don't account for shipping)
http://www.worldpaintsupply.com/soni...oisture-meter/

[Leo_Gnardo]

These meters can be purchased at hardware and paint stores for between forty and seventy bucks. It's the same meter in most places. Only the price fluctuates.

Cool! The price is affordable now - gotta get one. Then I'll have an excuse to never pick up the brush.

My drafty old house for instance: 25% RH in the winter, 90%+ at times in the summer. Purposely practically no furniture. Fuzzy white mold appears on speaker cabs near the floor in summer. Eccchh... but that's the way it is. Maybe Mick's client's place is similar.

[Mick Bailey]

He lives in a stone house just a few miles from me. Our RH indoors today is 65% and that's pretty good. My house is stone too, built straight onto the earth in the 1500s with walls 27" thick. It's like living inside a wet bath sponge. Spongebob would love it here. There are only a few weeks in the year when the humidity indoors drops to below 60%, so I guess my customer's house is going to be similar.

[Chuck H]

I can't speak from experience, but perhaps keeping silica desiccant packets in the guitar cases could help. And don't store cases on the floor, like laying flat under a bed or some such. In any event I do think a new case is in order with the hydrometer discovery. Not sure how your places are heated, but when I used a wood stove we kept a kettle on the flat top so it would boil and rehydrate the air in the room. Otherwise it could become unbearably dry. So if you and your neighbor heat with wood perhaps keep the guitars in that room (away from the fire obviously).

[Mick Bailey]

I wondered about Silica Gel. At least one humidity-controlled case manufacturer uses this to dry out the air with quite a simple setup - a hygrometer and a couple of compartments either for a wet sponge, or silica gel. Not exactly automated, but better than nothing. The nice thing about Silica gel is that it can be dried out in a warm oven and then re-used. It does a wonderful job in my jars of dried Shitake mushrooms, otherwise they turn to mouldy leather.

I've had a similar corrosion problem with my 1960s Telestar. It had no signs of rust anywhere when I got it. As soon as it got put in a brand new case it started to go downhill. Now I keep it out and it's fine.

I'll send the link to these posts to my customer - I'm sure he'll find the advice helpful.

[Leo_Gnardo]

I wondered about Silica Gel. At least one humidity-controlled case manufacturer uses this to dry out the air with quite a simple setup - a hygrometer and a couple of compartments either for a wet sponge, or silica gel. Not exactly automated, but better than nothing. The nice thing about Silica gel is that it can be dried out in a warm oven and then re-used.

Silica gel may be of some help. First time I went to London (June 1984) one of the first things on my shopping list was silica gel. I bought a kilogram of it at an apothecary on Goldhawk Road. The purpose was to keep one particular Strat neck from bending this way or that in expected London humidity. Packed it into tea bags, put 'em in the case & that guitar stayed just as straight as it should. OTOH the weather wasn't especially damp nor was the 3rd floor apartment in Holland Park, same for Nomis Rehearsal studio. I can verify that a little lo-temp baking can dry and "revive" the gel crystals. The silica gel I got had a color-change chemical added, pink or blue, depending on wet or dry.

If that guitar's case is feeding stored dampness into the guitar, it's got to be changed. Depending on how many guitars he has, your client might want to consider building a special dry storage chamber in his house.

[Chuck H]

It does a wonderful job in my jars of dried Shitake mushrooms, otherwise they turn to mouldy leather.

Well, at least there one benefit to living in a wet climate... Mushrooms! Since you mention Shitake I'll guess that you grow them? I'm a mycophagist as well, but I just hunt. Plenty to go around here in the PNW so I've never looked into growing them.

To stay on topic, sort of, it may be possible to grow oyster mushrooms on that soggy guitar case

[Leo_Gnardo]

it may be possible to grow oyster mushrooms on that soggy guitar case

Geeze what a thought. Talk about funky. On the case OK, I hope not on the guitar too...

[Chuck H]

I saw a picture where I guy found them growing on a wooden chair in his house! Why not a guitar? Similar woods and finishes. But the mycelium is destructive since it feeds off the host and all. It wouldn't be the first fungus to eat a stringed instrument. I think you and I covered that on another thread though

[Mick Bailey]

Since you mention Shitake I'll guess that you grow them?

Sadly, I'm a fraud and transfer my store-bought Shiitake to preserving jars. My growing experience just resulted in food for Sciarid fly larvae. Sadly, around where I live there used to be carpets of edible fungi, but no more. Even the woodland boletus have disappeared. The last decent find I had was some white giant puff-balls which fried up with butter, garlic and black pepper like chicken fillets.