Inside of guitar body

[Henning]

Hello, do you have any idea of how the inside of the guitar body is "supposed to be"?
With "supposed to..." I mean, it can be worked smooth, with sand paper or left harsh, simply planed or chiseled. As well as smoothed surfaces or sharp edges left from chisel or plane.
(Why please?)

Regards

[Silly Moustache]

Hej, Henning,

It seems that you are determined to take a risk with your guitar to improve it's sound.

I am concerned for you that your efforts may not show a reward, but ....]

I am no luthier, but I have peered inside a good many guitars.

I have Collings and Eastman guitar where the inside braces are beautifully fashioned and look like beautiful "buildings" inside.
I also have a Martin and two Harmony guitars which look rather rough, but still sound good.

Lycka till!

[The Bard Rocks]

Typically, the interior is not finished to the same degree as the exterior. It will be open wood, no stain, varnish, poly, any of that stuff. But it will be smooth to the touch, with close-fitting interior parts (kerfing, blocks, bracing...) and little or no glue residue apparent.

Yes, there are exceptions, but that's what they are - exceptions. Some may be finished to a greater level than others, which I usually take to be a reflection of the care the maker has taken on the entire instrument. That is not always the case of course, but it's a usable rule of thumb.

[musicman1951]

I know how a guitar sounds. I have no idea what the inside of my guitars look like as I can't seem to work up the curiosity factor high enough to look. That doesn't mean I think my lack of interest is a virtue, just that it doesn't have anything to do with making music. I most definitely wouldn't do amateur woodworking in there.

[Mr. Jelly]

https://www.acousticguitarforum.com/...1&d=1653138184

[The Watchman]

SO, why isn't the inside finished in varnish, shellac, lacquer, etc.? Wouldn't this would reduce the impact of humidity changes, for example?

[jmjohnson]

A Martin and a Taylor.

[Rudy4]

Anyone fascinated with guitar interior treatment should also check out Lame Horse guitars. It's well worth a visit to their website!

[ewalling]

Originally Posted by musicman1951

I know how a guitar sounds. I have no idea what the inside of my guitars look like as I can't seem to work up the curiosity factor high enough to look. That doesn't mean I think my lack of interest is a virtue, just that it doesn't have anything to do with making music. I most definitely wouldn't do amateur woodworking in there.

Same for me - little idea or interest.

[zombywoof]

I play a 1942 Gibson J50. As was Gibson's way of doing things not one brace is feathered so it tucks under the lining. And the bracing and tone bars themselves look like they were whittled with a dull boy scout knife. To call the bracing rough-hewn would be a kindness. On top of that one of the book marched top pieces was accidentally flip flopped. But this guitar turns conventional wisdom about what a "properly" built guitar on is ear. When the second generation luthier who fixed it up for me gave it back he did so with the words "never let i out of your hands" saying his father used to call guitars which sounded like this one "once in a blue moon Gibsons." But I already knew this guitar had a magic to it. Still nice to hear.

[zombywoof]

Originally Posted by jmg257

A Martin and a Taylor.

The first thing I noticed had nothing to do with flawlessness of the build (or lack thereof) but how thick those back braces are.

[Sadie-f]

Originally Posted by The Watchman

SO, why isn't the inside finished in varnish, shellac, lacquer, etc.? Wouldn't this would reduce the impact of humidity changes, for example?

Varnishing the interior is another layer adding stiffness to the tone wood, builders are already working to minimize thickness of the exterior finish, and any layer on the opposite (in) side probably has more effect than three outside.

Additionally if there are ever braces that pop, interior finish will only make repairs harder.

The smoothness of the interior surfaces has zero impact on tone, the wavelength of sound at 20 kHz is 1.7 cm, so any feature smaller than that is not materially affecting sound.

[Mycroft]

Originally Posted by Henning

Hello, do you have any idea of how the inside of the guitar body is "supposed to be"?
With "supposed to..." I mean, it can be worked smooth, with sand paper or left harsh, simply planed or chiseled. As well as smoothed surfaces or sharp edges left from chisel or plane.
(Why please?)

Regards

They can be all over the map. From extremely smoothly finished to very rough. While it is nice to see fine fit and finishing, it may not have and effect on the sound over more rough finish if the guitar is properly built. Old Gibsons, for example, have a reputation for rough finish work, braces and whatnot. Original Weissenborns, from the 1920s and 30s, are usually very roughly finished yet are very highly sought after by lap steel aficionados. By comparison, with most modern boutique builders, very fine fit and finish is expect, nay, demanded.

Be very careful with trying to fine finish an existing guitar, either to try to improve the tone or to simply "tidy it up." t would require removing material from the braces and possibly the top plate. Which means removing structural support. There use to be a bit of an industry of people redoing the braces o 70s and 80s Martins and Gibson, which had gotten a reputation (a bit deservedly so) of being a bit "overbuilt" in an effort to lessen warranty repairs. These changes were usually done in an effort to "improve" the tone by shaving the braces. What it did was weaken the structural support, although that wasn't usually apparent right away. Instead the owner, unhappy because there was no dramatic improvement in tone, would do what they should have done in the first place: sell the guitar and look for a better one. But the new owner, or the one after that, down the road, having no idea of what had been down, would find the guitar imploding from the string tension a few years later.

There are some people who make a good living rebracing or retopping old, more inexpensive guitars. But be careful and make sure that they know what they are about. some are quite good at it. But I have to wonder what happened to their early efforts.

Eggs. I need Eggs...

[TBman]

Here's the inside of my new Pellerin SJ CW

[TomB'sox]

If you want to see the insides of a box or the back and or top braces before being made into a box, go to the custom section of the forum and pull up any of the build threads and you will see what craftmanship goes into what you can't see, or at least should IMO.

Lamehorse put so much effort into theirs, I wish my living room looked like their guitar insides.

In general, all bracing, end blocks, side supports, bridge plates, etc. are perfectly smooth and often rounded. Mark Hatcher makes a point to have no sharp edges anywhere that could possibly interfere with the transference of sound waves and designs his neck and tail blocks completely with that in mind.

Finally, some builders do put some finish on the insides of the back and sides to protect against humidity changes.