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Seal/Coat inside of the guitar
http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10101&t=17745		 Page 1 of 1
Author:  SkyHigh [ Wed Jun 25, 2008 7:18 pm ]
Post subject:  Seal/Coat inside of the guitar
Couple questions came to me when I was in middle of applying shallec to the side tapes and some of it went on off the tape on to the wood it self.

How many of you shallec or other method to seal inside of the guitar?

Are there any down sides to shallecing inside the whole guitar?

David
Author:  Brock Poling [ Wed Jun 25, 2008 7:58 pm ]
Post subject:  Re: Seal/Coat inside of the guitar
I am not sure if it is unnecessary or not. When you are building very very light I think there is a good case to be made for trying to retard the effects of humidity.

On some woods it goes on very easy and works great. Koa, Mahogany, etc. it couldn't be easier. Rosewoods (especially cocobolo) are a nightmare. It is very hard to apply and get it looking even. If you brush it you see brush marks, if you spray it it is either dry and dusty looking, or has that orange peel look. And cocobolo bleeds something fierce. You could easily turn the entire inside of your guitar orange. (ask me how I know. :( )

I haven't done it on my last few guitars. I think there are pros and cons to doing it. Right now the cons are winning.
Author:  Hesh [ Wed Jun 25, 2008 8:04 pm ]
Post subject:  Re: Seal/Coat inside of the guitar
Mario has mentioned before that some of the best sounding pre-war guitars were not smoothly finished inside. Tool and saw marks were visible and the sides and back were not sanded beyond perhaps 100 grit. Put shellac on this and you will have a greasy teenagers face.......

I wouldn't do it.
Author:  Brock Poling [ Wed Jun 25, 2008 9:26 pm ]
Post subject:  Re: Seal/Coat inside of the guitar
Hesh wrote:
Mario has mentioned before that some of the best sounding pre-war guitars were not smoothly finished inside. Tool and saw marks were visible and the sides and back were not sanded beyond perhaps 100 grit. Put shellac on this and you will have a greasy teenagers face.......

I wouldn't do it.


Scratch that. Responding to a different post.
Author:  gozierdt [ Thu Jun 26, 2008 10:49 am ]
Post subject:  Re: Seal/Coat inside of the guitar
I did a light shellac finish on the inside of my latest guitar. It's a small size "0" with an easily removable
neck for travel. Because it will see rapid changes in relative humidity, and it's lightly built,I finished it inside
and out. Sounds fine so far, and I think the inside looks better than it might have unfinished. I used sapele
for B & S, and it has such big pores that I suspect the epoxy filler would have come through and shown on
the inside. At least that's what happened all over with the shellac (I know, the epoxy is higher viscosity,
but these are BIG pores).
Author:  K.O. [ Thu Jun 26, 2008 10:57 am ]
Post subject:  Re: Seal/Coat inside of the guitar
Brock Poling wrote:
Hesh wrote:
Mario has mentioned before that some of the best sounding pre-war guitars were not smoothly finished inside. Tool and saw marks were visible and the sides and back were not sanded beyond perhaps 100 grit. Put shellac on this and you will have a greasy teenagers face.......

I wouldn't do it.


Scratch that. Responding to a different post.




idunno ??
Author:  Mark Tripp [ Thu Jun 26, 2008 1:01 pm ]
Post subject:  Re: Seal/Coat inside of the guitar
I shellac the inside, lightly - learned that from Somogyi...

That being said, I don't think it makes a difference in tone either way.

-Mark
Author:  JRE Productions [ Thu Jun 26, 2008 1:57 pm ]
Post subject:  Re: Seal/Coat inside of the guitar
Reading thru the Benedetto book on Archtops, I thought he said it was a good practice to use shellac on the inside of the guitar to slow down the affects of humidity. Stating something to the affect of: Once the top is finished the back becomes supseptible to absorbing moisture at different rates the the front. This could cause cracks and splits.

I just started reading the book and have only perused it. So I may have miss interpited what he was saying. I will be diving into the book in more detail in the next week or so.

Joe
Author:  Bill Greene [ Thu Jun 26, 2008 6:17 pm ]
Post subject:  Re: Seal/Coat inside of the guitar
Yes, I know a guy with lots of experience and he does it, and says it's for that very reason: just trying to slow the affects of humidity. But I suppose there is the issue of having to repair something on the inside.
Author:  Blain [ Thu Jun 26, 2008 10:45 pm ]
Post subject:  Re: Seal/Coat inside of the guitar
I've been wanting to try this for quite a while so maybe I'll do it on my next.

I wouldn't necessairly try to put a nice gloss on the inside but would be interested in putting enough to protect from Humidity.
Author:  JRE Productions [ Fri Jun 27, 2008 1:56 pm ]
Post subject:  Re: Seal/Coat inside of the guitar
I think I will just try thinning down some shellac to a very thin consistancy. Then spray it on the inside of the guitar. Sort of a white-wash type coat. Nothing too thick at all. I am still weeks away from this stage on my new build, but may post my observations at that time.

Joe
Author:  GregG [ Fri Jun 27, 2008 6:00 pm ]
Post subject:  Re: Seal/Coat inside of the guitar
Don't use the shellac on cocobolo, it's a mess, sheen variances...yikes!

GG
Author:  fryovanni [ Sun Jun 29, 2008 11:17 am ]
Post subject:  Re: Seal/Coat inside of the guitar
This is a subject that comes up often. The cons- more work. smoother surface(not sure how much a thin layer of shellac would honestly smooth a surface, but if you really wanted I am sure you could leave the surface slightly ruffer then apply your wash coat), makes it tuffer to fix cracks(I suppose there are two ways to look at that, it may reduce the chances of a crack to begin with, and a wash coat of shellac is only going to make it slightly more difficult to repair a crack), possible dampening(a wash coat of shellac is pretty thin and light, likely not much of a factor), a wash coat is not likely to be as pretty as a full finish(of course this is the inside of a box, so how significant that is depends on how "pretty" you need the inside of the box). The Pros- Basic woodworking rule do the same to both sides(although a wash coat will not act to slow moisture as well as a full finish), Will slow very rapid changes in moisture, slower changes over short periods may improve stability in the instrument for a performance(tuning, more consistent output and such).

Either way, there are a lot of guitars out there that have no finish inside the box. The benifits will likely be slight if any for people who care for their instruments and do not have to subject them to rapid changes in moisture. It is hard to gauge long term effects unless you can pool data, and most intruments we observe of any age have no finish inside. Of course cracking is an issue, and we know rapid changes are tuffer on an instrument than gradual. So I can see the logic in a bit of insurance, and I can see why people also choose not to spend the time(some customers may see it as irregular also, others may appreciate the effort, a bit of a wild card there). I have done both, noticed little difference, but did not anticipate any notable difference either.

Rich
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