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I was brushing shellac on the side tapes of one of my current builds yesterday (mahogany/sitka dread), and on a whim I decided to brush a coat of light blonde shellac on the entire inside of the guitar(except for the top). So now the sides, back, blocks and linings all have a coat of shellac on them on the inside and it looks amazing! Does anyone else do this?
- Justin

I haven't done this, but I have seen a couple of instruments that have had some finish work on the inside. Can't really remember any makers names though.

I'm sure there would have to be a reason that this isn't a common practice, other that the fact that it is more work than leaving the inside unfinished.

Cal

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Remember, there are no stupid questions, only stupid answers!

I spoke with one master about it ... he seemed to think you might lose some tone... but as most things in this its a matter of personal choice .. Jody

Many archtop builders routinely shellac the inside of their guitars. I think it adds a nice touch seeing the glow of the back when you peer inside the soundhole or "f" hole.

I finish the inside of mine with shellac, I think it looks great.

GG

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Gwaltney Guitars

For clarification, I just used one coat of a 2 lb cut shellac. It's not enough to qualify as a finish (it's barely a sealer coat). I don't think it will have any effect on tone because I did not body it up at all. It does however, bring out the color and grain of the wood and makes it look nice...

The way I understand it is that it could well be a good idea...
The inside of the back of the guitar reflects sound - a hard, smooth surface is a better reflector - makes sense to me!

This has been discussed here before and what I remember from those threads is this:

Some of the most highly prized pre-war instruments were in fact rough inside, some fuzzy wood, tool marks etc. After I heard that I stopped sanding my arse off on the insides of my own guitars........

I also think that someone made the point that in the event of needing some repair the shellac may need to be removed in the area(s) in question.

So I would question any claims that it will sound better as yet another case of psycho-acoustics but I agree that it looks nice.

Oh good...I think I'll start distressing the inside of my completed guitars until I begin to hear better sound! Perhaps filling up the inside with broken glass and shaking it for a few hours might just do the trick!

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JJ
Napa, CA
http://www.DonohueGuitars.com

JJ the easiest way to do this is before you attach the neck put the guitar body in the clothes dryer with a hand full of finger plane blades and set the dryer to wash & wear........

I dry Sony this way too but without the finger plane blades, he always dulls them and then I have to resharpen them......

A good many of us are proponents of not going too smooth on the interiors. It's been discussed here enough that there's no need to explain why. Just search the archives....

Bottom line: if the instrument(s) that turn you on and made you want to start building have finish on the interior, then finish yours, too. if, on the other hand, they don't(most likely the case), then why are you swimming upstream?

I see classicals like this sometimes, including my Kohno.

I tried this on my first and the comments I got were always the same, 'Jeez, what a bright sounding guitar'... I think that was a polite way of saying it sounded too shrill... I'll never do that again...

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I'd like to be able to prove, just for once, that money wouldn't make me happy...

No, don't!! *glares*



I still sand mine to a fine grit. That "ritual" originated from being a guitarist for longer than being a luthier; when on the hunt for a new guitar one of the first things you do bar playing and checking the neck is judging the workmanship inside the soundbox.

Klepper full on finishes some/all of his guitars. Has kind of a cool look to it but I don't know if I'd use that technique.

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Billy Dean Thomas
Covina, CA

"Multi famam, conscientiam, pauci verentur."
(Many fear their reputation, few their conscience)

No need to glare Sam...

I typically shine up the inside of the backs and sides prior to bracing with very fine grades down to 800 grit. I've never noticed any harshness in the sound...but then again, I have never done a controlled experiment either.

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JJ
Napa, CA
http://www.DonohueGuitars.com

I used to shellac the inside (thin coat). Now I don't.

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Howard Klepper
http://www.klepperguitars.com

When all else fails, clean the shop.

Howard, why don't you now? Was it cause you didn't see any difference in tone?

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"After forty-nine years of violin building, I have decided that the search for a varnish is similar to the fox hunt. The fun is in the hunt."
Jack Batts Maker and Repairer of Fine Violins

I have built one commission with the inside sealed with 1lb shellac it sounded fine no issues at all. I have a Bellucci concert classical it appears to be sealed with vinyl sealer on the inside. It looks nice and sound great. I no case do I feel it has muted the tone any significant amount. there are several builders that profess that painting the lower bout of the inside top adds tone. I can’t really see how but I doubt it hurt anything.

Maybe, without exposed wood (on the inside), it will make it tougher to reach humidity equilibrium?

Mike

I am coming around to that place too. I am doing it now, but seriously thinking about stopping.

Here are a few random thoughts that relate.

1) If you use double sides you will not always be able to get all the epoxy seep through off making it almost necessary to do something to the inside SIDES to hide this.

2) Mahogny, Koa and other porus woods seem to take the shellac well without witness lines. Rosewoods and Ebonies by contrast are difficult to get "right". It is just a cosmetic thing, but it bugs me... a lot.

3) I would seriously advise you to avoid shellacing the inside of cocobolo guitars with a brush or a rag..... unless you want all your braces orange (ask me how I know. )


I don't do it for any mystical tone enhancement. My plates are very thin and I do it to slow the effects of changes in humidity... but given all the down sides, I am seriously re thinking its "benefits"

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Brock Poling
Columbus, Ohio
http://www.polingguitars.com

Like Brock, I never did it for reasons of tone. I did it to stabilize the wood by slowing its response to humidity changes. The downside that I see is making gluing patches more difficult in hard to reach places. But after I considered the longevity of so many instruments without an inside finish, and the greater care that most owners now give to humidity control, I decided it was not needed.

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Howard Klepper
http://www.klepperguitars.com

When all else fails, clean the shop.

A light coat of shellac is not likely to affect moisture penetration. Studies have shown that wood eventually equilibrates even when sealed with a finish-thickness coating on all surfaces.
I think it is just a matter of personal preference. To me it is just a bit of extra work with once more chance for something to go wrong.

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It's not the miles ahead, it's the stone in your shoe


In Markham,Virginia

True enough... the idea was to slow the changes, not prevent them. That would (or so the theory goes) reduce risk in quickly moving from one humidity extreme to another.

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Brock Poling
Columbus, Ohio
http://www.polingguitars.com

I have used a light coat of shellac on the interior, and have left it bare. My reasons for finishing was to slow the transfer, not stop it. Really I think it is a measure that would take a considerable amount of time to tell if it made a notable difference in terms of durability, and then how would you know for sure if other factors had not come into play over those decades . Where I saw the most potential for a slowing or more even transfer was possibly during an evening of play (a few hours). Say you drive to an outdoor event, pull the guitar out of the case, play for an afternoon into the evening. My hope was slowing the transfer, maybe overall stability would be improved for that period. I never really noticed a big difference though, but then again I have never really put them to a severe test (and don't plan on it, unless by chance I can't avoid it).