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A cautionary tale - solid wood soundboards do not like damp conditions!

So, I finished this last week, and have been enjoying playing it:

Yesterday morning, before leaving for work I decided to stash it upstairs, in a bedroom and leant it against an external wall. When I got back from work, I picked it up to play and noticed immediately that the grain had raised on the neck (possibly the Danish oil had not fully cured yet) and the guitar sounded unpleasantly bassy and muddy.

I messed about with the intonation a bit, but then came to realise the soundboard had gone all spongy, and even slight pressure would cause the sound to warble, like a wah pedal!

So anyway, long story short, don't do this if you live somewhere as wet as Manchester, especially if you are in an old house in need of damp proofing!

...and I'll start on my new soundboard tonight - I didn't really like the soundholes anyway :)

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Permalink Reply by Randy S. Bretz on December 12, 2013 at 7:38pm

That's why I use Deft spray lacquer on all my builds, to protect them from the elements !!

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Permalink Reply by Richey Kay on December 12, 2013 at 7:48pm

Thanks for the tip Randy - might have to look into that!

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Permalink Reply by Slowpaw Steve T on December 12, 2013 at 7:59pm

i always use a couple of coats of lacquer on all my builds, complete protection against cold or damp conditions if they arise, be careful where you store them! (-:

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Permalink Reply by Richey Kay on December 12, 2013 at 8:05pm

Well now I know! - would a poly varnish work to the same effect? I have some knocking around...

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Permalink Reply by Richey Kay on December 13, 2013 at 7:20pm

Update - I left the guitar in front of a radiator yesterday and it seems to have pretty much returned to normal... I think the humidity in my house must be too high or something. I think I'll have to either build some cases or start stuffing silica gel into my builds!

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Permalink Reply by Order99 on December 14, 2013 at 7:41pm

Can you keep it near a source of neutral humidity long enough to give it a few good coats? Normally I like to:

1) dehumidify the wood to a near brittle dryness

2) apply Danish Oil and watch it fast-dry as the starved wood soaks up the finish

3) repeat until the wood actually takes the recommended time to dry

4) buff with 450 grit , damp wipe and three light coats of lacquer.

I find that forcing the pores of the wood to 'feast' on the Danish Oil prior to sealing leads to less swelling/shrinking in the long term than leaving the normal amounts of water vapor therein. Failing a proper long-term environment for treating the finished product, steps 1 and 4 might be the 'good enough' solution...

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Permalink Reply by Richey Kay on December 14, 2013 at 8:28pm

Thanks for the insight. I'm intending to buy a hygrometer so I can find out which parts of my house are unsuitable for storing my guitars. In the meantime this gives me more ammunition to get my landlord to fix the problem 'your house is killing my guitars!'

When you say 'dehumidify the wood' - do you mean with a blow dryer or something? Or a low oven? I should mention that I don't buy my wood from a luthier supplier, but from a model aeroplane parts supplier...

Would any plastic finish do the same job? I have a can of Plasti-Kote satin spray varnish at home already.

Cheers!

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Permalink Reply by Order99 on December 14, 2013 at 10:59pm

I am fortunate enough to have a nice, sunny nook in front of a well-insulated window to dry my babies...I have on occasion used my oven set to no higher than 110 Farenheit for 6 hours to dehumidify-I wouldn't go too much over body temp for fear of softening any glues in the box.

Other finishes may alter the tone very slightly, and this may not be a bad thing at all. Just make the wood 'thirsty' enough to soak your coating deep into the pores, the deeper the better, and less water vapor in the wood as a result. I like to use oils because the wood seems to accept it better, but i've also just used varnishes and even poly-coats to decent effect.

To be honest, I can't take credit for this technique as it has been used by many luthiers and furniture makers for centuries-including my late Grandfather, who could put a French Polish on cheap plywood, and who (before epoxy was king) once weatherproofed a wooden boat by pre-curing the planks, then swelling the wood by soaking it in kerosene after joining, drying the result and varnishing for a final seal. Eventually my Grandfather decided he was too old to sail, and sold the boat...thirty-five years later. Top that, Fiberglass... :)

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Permalink Reply by Richey Kay on December 15, 2013 at 12:42am

Wow, I'll have to give it a go. This must be why high end guitar makers are always after well aged wood. I don't think I'll attempt soaking anything in kerosene, however!

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Permalink Reply by Order99 on December 15, 2013 at 8:15am

I wouldn't recommend kerosene for a guitar either, especially with a pick-up. Not unless you want to be LITERALLY 'Cooking with Gas' next time you play a crowd! :0

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Permalink Reply by Michael Fred Johnson on December 15, 2013 at 1:36am

I always give the timber a couple of coats of sanding sealer before applying the final finish of aerosol spray lacquer

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Permalink Reply by Bluesheart on December 18, 2013 at 10:13am

If the problem is from high humidity and you seal the face of the wood, won't the humidity just get into the wood from inside the box and then maybe cause bowing , cracking etc since one side is now waterproof and the other is not? Recently when steaming a piece of veneer, even without finish on one side, I could curl it into a tube by just applying stem on one side. (which in this case is exactly what I wanted to do, I was suprised at how well it worked!)