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I saw a [Kim] Walker guitar this summer that appeared to have a thin (varnish?) finish on the interior surfaces of the sides and back. I am not sure if the underside of the top had anything on it.

Have any of you any knowledge of such finish techniques? Pro's con's? I assume it is to retard mositure absorbtion and to quash RH affects. What effects would this have on tone?

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tim...
http://www.mcknightguitars.com

Kohno, one of Japan's best classical builders, finishes the interior of its guitars. I have an Aria MH-100 classical, a handbuilt Hauser copy, which also has a finished interior. It is a very thin finish, whatever it is -- probably shellac or varnish. The MH-100 does not have finish applied to the underside of the top, and it is my understanding that Kohno does not finish the underside of its tops either.

I have always suspected that these builders did this to brighten up the tone for more than any other reason, the goal being to make the interior more reflective and less acoustically absorbant. In that respect, I think it is a good idea. I have not finished the interior of any of my guitars, but I do try to sand and scrape them quite smooth so that they are more acoustically reflective. Does it really make much of a difference? Honestly, I don't know, but the way I see it, I don't see what it would hurt if one chose to finish a guitar's insides.

Best,

Michael

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Live to Play, Play to Live

I don't see what it would hurt if one chose to finish a guitar's insides.

...until the time comes to do repairs.

I've often wondered about this. Fine furniture is often finished on the inside. I'm thinking I'll finish the guitar I am working on now, but just the back and sides, with a coat or two of shellac.

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"An adventure is only an inconvenience rightly considered. An inconvenience is an adventure wrongly considered." G. K. Chesterton.

It would seem that a thin layer of shellac could work as a sealer without a problem. There are many posts on this site that state how easy it is to repair an instrument that is French polished (shellac).

Philip

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aka konacat

If you think my playing is bad you should hear me sing!
Practice breeds confidence and confidence breeds competence. Unfortunately, I'm stuck in practice.

[QUOTE=konacat] It would seem that a thin layer of shellac could work as a sealer without a problem. There are many posts on this site that state how easy it is to repair an instrument that is French polished (shellac).

Philip[/QUOTE]

References to 'easy to repair', when it comes to shellac, refer to the ease of *finish* repair or touch up. Mario is referring to having to do structural repairs on the inside of a finished guitar, given that many (most?) glues will not stick to a finished surface.

The reason ive heard at school is that it is to slow down humidity issues. I have done it in one guitar, two layers of nitro, and it was frustrating to get it to look good..

I really dont understand the problems when it comes to repair. i dont take anybodys side here since i have really little experience, but if something popps of you glue it back and if it cracks you fill the crack, right?

It may help stabilize humidity exchange, but I don't see how it would affect things hugely. You protect guitars from major swings in humidity, and thin film finishes are not moisture-proof barriers. Millions of guitars out there have no finish at all on the inside. I've been tempted to do a very thin wash-coat of shellac on the inside, because a) that sands off in seconds and b) it keeps the inside looking neater/cleaner, but honestly, I remain unconvinced of its necessity.

When it comes to repair: if something pops and you didn't glue it with hide glue, you clean the surfaces, and glue. If something cracks (ie, breaks), you glue it together more often than fill it, and often want to/have to reinforce the break with a cleat or something similar, and then you're faced with having to remove the finish before being able to glue anything in place properly.

On flattops and archtops -- finishing the inside is purely cosmetic.

I put a very thin wiped on coat of schellac on one guitar. Just simply because the wood (Bob's moon scape sapele) needed to be seen even on the inside of the guitar. I didn't do the inside of the top and haven't done another since but I didn't notice a difference in tone. The shellac was very thin.

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Tickle your guitar daily, and it'll tickle you back.

I think it might keep the guitar from mellowing with age, espedially if the top was done. If it's not bone dry, it can't continue to dry. Who knows, the continual absorption and loss of moisture might be what gives those old guitars such a sweet sound.

Ron

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OLD MAN formerly (and formally) known as:

Ron Wisdom

Somewhere in the middle of Arkansas......

Maybe you could finish the inside with some nice curtains and carpet so that the guitar feels at home sooner

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Dave White
De Faoite Stringed Instruments
". . . the one thing a machine just can't do is give you character and personalities and sometimes that comes with flaws, but it always comes with humanity" Monty Don talking about hand weaving, "Mastercrafts", Weaving, BBC March 2010

Piano soundboards are finished both sides but still move to humidity changes

KiwiCraig

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CRAIG LAWRENCE of AUSTRALIA
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Thnkas for all of the comments fellas.

David: You should have been a commedian ;)

I might build two identical guitars and A/B them side by side. I have a batch going now that I can try that on. I will keep you posted as to what I learn... Thaks again...

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tim...
http://www.mcknightguitars.com

>I might build two identical guitars and A/B them side by side.<

Would this were possible.

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Howard Klepper
http://www.klepperguitars.com

When all else fails, clean the shop.

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[QUOTE=Dave White] Maybe you could finish the inside with some nice curtains and carpet so that the guitar feels at home sooner [/QUOTE]

The Lawrence LLewelyn-Bowen of the luthiery world (you've got to be British)

Colin

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I don't believe in anything, I simply make use of a set of reasonable working hypotheses.