Official Luthiers Forum!
http://mowrystrings.luthiersforum.com/forum/

Is it wrong to seal the inside soundbox?
http://mowrystrings.luthiersforum.com/forum/viewtopic.php?f=10102&t=13865		 Page 1 of 1
Author:  Strung out [ Tue Oct 02, 2007 10:10 pm ]
Post subject: 

Hi all,


Just found your site and joined immediately.


Having worked with my hands for many years ,I have recently developed a real passion for tinkering with and fixing up guitars.Hope to one day get up enough equipement  (and confidence) to build my own. Meanwhile I'm having a ball in my own little world of guitars and I am collecting guitars,wood and tools as I come across them. I store them next to my wine .My family and friends think I am a kook and can't see the value of collecting wood, or guitars for that matter.


That's middle age for you.


I tell my wife that a love affair with guitars is better than an affair with another woman.


I justify the cost by saying:At least when the affair is over you can always sell the guitars.Last I heard it is still illegal to sell a woman.


My question :


 I picked up a nice  new 3/4 classical for my kid. I am fitting it with a fishman pick up. I have had thoughts about sealing the inside of the sound box with varnish as a way of protecting it from swelling in the 60 - 80% + humidity environment that I live in ( the equator). I have a Hirade that appears sealed inside and I have noticed several other Japanese luthiers (Asturias for another) have also done so. I note that I have never seen an american guitar sealed inside.


Any thoughts ?


Strung out
Author:  Ray Pepalis [ Tue Oct 02, 2007 11:43 pm ]
Post subject: 
How would you seal the inside of the box?
Author:  Bruce Dickey [ Wed Oct 03, 2007 12:55 am ]
Post subject: 
Most luthiers cringe at the idea for one main reason, repair. Sealed wood has to be sanded finish free to reglue.

I agree if we had no qualms about repair, that it might just impede the influx of humidity to the wood. However, that same finish would impede a too wet guitar from drying out quickly, right?

Taylor Guitar in El Cajon, California did some tests. They found that finish is not a complete moisture barrier and that if left long enough in a humid environment, that a guitar would become saturated. They have some great TECH sheets on too dry and too wet guitars, and are available through mail or maybe even online?

Glad you found the OLF and Welcome. Singapore, that's a fur piece down the dirt road from my house.....   
Author:  WaddyThomson [ Wed Oct 03, 2007 12:57 am ]
Post subject: 
Welcome to the OLF, ???.  Someone will pop with an answer before long.  It would, however, be nice to have, maybe, a first name, to attach to your handle, for more personal interaction.  This is a great place, with lots of information available, and individuals willing to share experience and knowledge, but it comes quicker when they can make a personal connection.
Author:  senunkan [ Wed Oct 03, 2007 1:02 am ]
Post subject: 
Hi Strung Out,

I am from Singapore too!
My '96 Ross Gutmeier Fleta copy guitar has its inside sealed actually.
I guess there is nothing wrong with sealing inside.

Welcome to the forum.
This is a wonderful forum.
All the ppl here are most willing to help if you have any question regarding guitar
They offered me much valuable advice when I post my question.

Sen!
Author:  Todd Rose [ Wed Oct 03, 2007 1:09 am ]
Post subject: 
Hello down there,

My brother and his family live in Singapore. I've only been there once, and that was ten years ago. I had a good time, though, and traveled from there all over SE Asia for several months. It was an amazing, mind-expanding experience.

Anyway, my first questions would be about how the guitar is doing in the Singaporean humidity as it is. If the humidity there stays pretty well between 60% and 80% most of the time, that's high humidity, but it's not that great of a fluctuation. Here in NY State, for example, we go from almost no humidity in the winter to extreme humidity in the summer - much greater fluctuation than what you experience. So, I'd tend to worry a lot more about a guitar here than in Singapore, unless your guitar was built in relatively dry conditions and it's having real problems in that humidity; if that's the case, sealing it inside won't solve the problem anyway. Keeping it in an air conditioned room would be about all you could do. Sealing or finishing wood (whether it's on one side only or inside and out) doesn't stop moisture exchange; it only slows it down. If the guitar were going to be subject to dramatic and relatively rapid changes in humidity, having the inside sealed might help prevent cracking. But, generally speaking, the only way to protect a guitar from damage due to humidity fluctuation is to prevent it from being subjected to extreme humidity fluctuation. So, once again, it sounds like fluctuation isn't really the issue in your case, but constant high humidity might be an issue if the swelled wood is causing problems. If there are serious playability problems and you can't adequately control the humidity of the environment the guitar lives in, it's probably best sent back to spend its life a drier climate and replaced with a guitar built in more humid conditions - maybe a good reason to go ahead and build one yourself!

Good luck, and say Hi to my bro if you run into him at the market.
Author:  Todd Rose [ Wed Oct 03, 2007 1:14 am ]
Post subject: 
[QUOTE=Todd Rose] If there are serious playability problems and you can't adequately control the humidity of the environment the guitar lives in, it's probably best sent back to spend its life a drier climate [/QUOTE]

I meant, "to spend its life _in_ a drier climate"...
Author:  Bill Bergman [ Wed Oct 03, 2007 1:46 am ]
Post subject: 
I have heard a number of times that, if you seal inside, only seal the back and sides to avoid tone compromise of the top. If it is a 3/4 size commercial classical (such as Aria Pepe), my guess is that the back and sides may be laminate, which probably is relatively sturdy and resistant to travails of moisture change. If that is the case, there would be no benefit to sealing.
Author:  Strung out [ Wed Oct 03, 2007 2:17 am ]
Post subject: 

Thanks all,


By the way, the name is Rob,sorry.


I didn't think about future repairs and that "seals" it for me.


I also had concerns about what would happen to the top if it were sealed underneath.


Thanks for mentioning the Taylor papers.I have several Taylors and have read their papers on "wet Guitars".I am quite versed on keeping them in good order.


I'll bet the example they mention in the "wet" paper came from here. 


Being a foreigner in Singapore, I have my house airconditioned all the time, and yet still shower 3-4 times a day.


I keep my guitars and wood at 45 to 50% humidity and 71 degrees .I was worried about my kid wanting to take the guitar outside to meet friends, etc and it turning into a sponge.


Most secondhand guitars in this area have warped tops and have the tone of a wet bag of spuds.I stay away from them as they obviously have been outside.


It's a solid 80 to 90% there most days.


Thanks all.  
Author:  Alan Carruth [ Wed Oct 03, 2007 6:27 am ]
Post subject: 
Iirc, back in the '60s the US Navy found that even a quarter inch of epoxy won't stop wood from picking up moisture eventually. That's when they went to fiberglass liberty boats.

Sealing the top adds weight, and any excess weight on the top is bad.

Moisture in the wood makes it more dense than dryer wood, of course, and also less stiff. If you're going to build any guitars in your humid climate you should, in thoery, make the tops a bit thicker than 'normal'. In practice I'd bet the difference would not amount to much.

Other than that, any guitars you build should be fine as long as the relative humidity is stable and no more than about 20% lower than it was when you built the guitar. I would _not_ ship any of your guitars to New England.
Author:  Allen McFarlen [ Wed Oct 03, 2007 7:20 am ]
Post subject: 
I've been sealing the entire inside of my guitars with a couple thin coats of shellac just in the hope of slowing down the moisture transfer.

Here in Cairns we had a day of 40% RH on Sunday and 8 hours later it had jumper to 89%. You can also drive for and hour up onto the table lands and have that type of fluctuation of very wet to really dry almost any day of the year. If you travel a couple more hundred km's inland you can get to some seriously dry areas.

I would be interested in anyones else's experiences dealing with wide swings in RH like this and how they handle it.
Author:  Martin Turner [ Wed Oct 03, 2007 8:51 am ]
Post subject: 
Dry as a bone during the summer down in Adelaide but during winter
humidity can get up to 90% plus. I have a ceramic panel heater going during
winter months and during the summer the dehumidifier is on duty.
Author:  James Orr [ Wed Oct 03, 2007 10:02 am ]
Post subject: 
Kim Walker seals his guitar interiors with something. With what, I'm not
sure.
Author:  James Ringelspaugh [ Wed Oct 03, 2007 1:17 pm ]
Post subject: 
I have started sealing the inside of my guitars with a wash coat of shellac. It is not a very good barrier against moisture exchange, but were I to spill a glass of water inside or get caught in a rain storm on stage somewhere it should retard moisture exchange long enough to get a towel inside before the wood was soaked. Plus I think it looks good.

Some people (myself included) bake their tops to retard expansion and contraction of the wood with changes in humidity. Search the archives and you'll find plenty of information about this practice and theory of why it works.
Author:  Kevin Gallagher [ Wed Oct 03, 2007 1:36 pm ]
Post subject: 
    Wrong?         No.

    Necessary?   Also...N o.

    Beneficial?    Y ou got it....No.



Regards,
Kevin Gallagher/Omega Guitars
Author:  Colin S [ Wed Oct 03, 2007 8:24 pm ]
Post subject: 
[QUOTE=Kevin Gallagher]       Wrong?          No.

     Necessary?   Al so...N o.

     Beneficial?   & nbsp;Y ou got it....No.



Regards,
Kevin Gallagher/Omega Guitars [/QUOTE]

Now that's the model answer.

Colin
Page 1 of 1 All times are UTC - 5 hours
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/