View Full Version : Humidity-proofing question
grandmainger
Sep-02-2004, 3:35pm
I was wondering if anyone has ever tried either varnishing or waxing the inside of a mandolin, in order to minimise the effects of variying humidity in the air.
Presumably, a thin coat of varnish would do the job nicely, and perhaps not alter the sound too much... Just wondering... http://www.mandolincafe.net/iB_html/non-cgi/emoticons/rock.gif
Luthier Vandross
Sep-02-2004, 3:53pm
Not for humidity control.
There is an old secret, I can't tell you... it's not about humidity, but you may find a coating inside some instruments, and it would be sticky. ;)
M
I recall some years back that one of the Japanese companies put some sort of finish on the inside of their acoustic guitars. #I think it was Yamaha; I don't know if they still do or not, as I haven't looked that closely at any recent ones. #Perhaps it was to prevent the type of damage discussed years ago in a "Bluegrass Unlimited" article, where an angry wife chose to use her husband's guitar for revenge when she caught him with another woman
at the club where his Bluegrass band was playing. http://www.mandolincafe.net/iB_html/non-cgi/emoticons/biggrin.gif
Bill Snyder
Sep-02-2004, 7:39pm
This topic comes up periodically at the Musical Instrument Makers Forum and although one or two finish the inside, the general concesus is that it is not worth doing and several posters think it is a bad idea. One of the reasons given for not finishing the inside was the finish impeding future repairs.
resonant68
Sep-02-2004, 9:39pm
I've used a sealant inside two of my three mandolins.Being in south Alabama where the humidity can range from 35% R.H. in the winter to 95% R.H. in the summer I thought I needed some humidity protection inside my instruments.Plus in the summer the R.H. can be 40%+/- inside my house and 95%+/- outside where I do most of my picking.
I saw a thread here a year or two ago about this same thing and someone suggested using a "wash coat" of shellac inside.But as I recall there were mixed feelings about it then.
I too would like to know what more experienced builders do.
I have had many acoustic guitars in the past that were clearly coated inside with something.But I don't know(or can't tell) if my Gibson J45 has any coating or not. And it sounds better than the others.....what do you guys do?
Luthier Vandross
Sep-03-2004, 4:15am
I think Yamaha... just didn't plug the hole before the finish went on.
People have used shellac, and glue... I use glue, when I do... rarely, and just for fun.
M
Chris Baird
Sep-03-2004, 5:59am
Robert Benedetto says to use a sealer on the inside of archtop guitars. I put one 1/2" strip of sealer right on the seam and that is all. It may be that years worth of oxidation is a good thing for an instrument and may be impeaded with a completely sealed up mandolin.
sunburst
Sep-03-2004, 7:46am
No finish seals completely.
Somebody did some tests many years ago (I don't remember any details) to see what were the resistances of various finishes to moisture. The only finish that nearly sealed the wood was gold leaf.
If you want to gold leaf the inside of your mandolin it might look pretty cool in the light! As far as other finishes go...why bother?
grandmainger
Sep-03-2004, 7:57am
Sheesh... gold plated mandolin... Droooool !
sunburst
Sep-03-2004, 8:02am
Sheesh... gold plated mandolin... Droooool !
http://www.mandolincafe.net/iB_html/non-cgi/emoticons/cool.gif
TommyK
Sep-03-2004, 10:31am
Sheesh... gold plated mandolin... Droooool !
Actually, I think sealing the INSIDE with Gold leaf would be called Gold FILLED! http://www.mandolincafe.net/iB_html/non-cgi/emoticons/biggrin.gif
Now you can drool. http://www.mandolincafe.net/iB_html/non-cgi/emoticons/tounge.gif
TommyK
Sep-03-2004, 10:34am
Pop. Mech. ran an article years ago when we used to get a tax credit for sealing up and insulating our homes ('80's?) on vapor barriers. They suggested on old construciton, lath and plaster walls could be sealed by painting the interior of the outside wall with Aluminum (that's aluminnium to you Brits.) paint. Then painting with the desired color or wall papering.
Aluminum paint might be cheaper than gold leaf for those on a tight budget.
http://www.mandolincafe.net/iB_html/non-cgi/emoticons/biggrin.gif
TommyK
Sep-03-2004, 11:09am
Seems to me that if you and your <insert wooden instrument here> live in a extremely humid or arid region that adversely affects the life and function of your instrument that sealing the inside would make sense. #The 'purists' out there may tell you, emphatically, "don't do it." #If it's your instrument I say do it. #Be aware that it may affect the resale value do to the 'purist' take on the issue. #But, if you plan to keep a long time that may not be an issue. #If it is a 'collector's item', then all bets are off. #You should keep it in a humidity / temp controlled case in a temp/humidity controlled room and not let it out, except for special occaisions. #
The smart alek remarks not withstanding, mine included, I'd opt for a low gloss coating of your choice. #Even if it only 'slows' the moisture movement process, some is better than none and keep your case and storage area humidity controlled. #I live in a mostly dry area. I keep my guit-box humidified, but in your case, there should be a instrument dehumidifier available. #Maybe collect those little packets of 'dessicant' furniture manufacturers toss in with kitchen cabinets and the like to toss in your case. #This, I would guess, help keep the humidity undercontrol between playings. #
Anybody know of a instrument 'dehumidifier' or use a dessicant? Does dessicant need to be dried out periodically?
John Bertotti
Sep-03-2004, 11:24am
Desiccant does need to be dries occasionally. Usually by baking at a certain temp. I don't know about vapors though, you may not want to try this in your house till you know for sure.
As far as sealing the inside I think it is a good idea just to slow down the rate of change between environments. I have no proof. Someone on this board told me they used a thinned down varnish or shellac, i again don't remember which, as a light wash coat inside. I believe the wood need to breathe so sealing it completely wood be a problem maybe even cause a rot or mold growth. Let it breathe at a slower controlled rate. John
amowry
Sep-03-2004, 12:27pm
It really can present problems with repairs, though, so I'm not convinced that the potential benefit is worth it.
John Bertotti
Sep-04-2004, 10:55am
Some bowlbacks have lined the inside with what looks like thin plane shavings. I imagine this was for support but it could have a humidity conrtol effect. John
TommyK
Sep-08-2004, 6:03pm
I was wondering if anyone has ever tried either varnishing or waxing the inside of a mandolin, in order to minimise the effects of variying humidity in the air.
Presumably, a thin coat of varnish would do the job nicely, and perhaps not alter the sound too much... Just wondering... http://www.mandolincafe.net/iB_html/non-cgi/emoticons/rock.gif
Just for reference sake grandmainger, what is the age, condition, and pedigree of that damp mando?
If it's one of those i've seen sell (yeah right!) on ebay for $250,000 I think you'd want to treat it different that if it were a Johnson wannabe.
http://www.mandolincafe.net/iB_html/non-cgi/emoticons/coffee.gif http://www.mandolincafe.net/iB_html/non-cgi/emoticons/coffee.gif