Varnish on guitars?

[carmike]

I apologize if this is an ignorant question, but I'm still relatively new to guitars and I can't quite make sense of this...

...Why doesn't varnish on guitars affect their sound? There's a beautiful Collings for sale here at the moment, and it's got a very pretty, shiny top. Folks have commented that the varnish looks good -- and they're right. Seems like a lot of the semi-new Gibsons also have a lot of varnish on them, too. I suppose the same would go for guitars that are painted, maybe.

But wouldn't adding weight to the top of the guitar decrease the amount the top vibrates--and theoretically affect the sound? I mean, if builders are hand-carving the bracing to get it as light and thin as possible, in an effort to get the top as much movement as possible, wouldn't adding paint/varnish to the top work against that?

[jaymarsch]

Many more people will respond to this with more experience than me, but basically guitar makers are trying to balance protecting the wood while still keeping the top wood vibrating. Whether they are using French polish, nitro cellulose lacquer, poly or varnish, they will put on a layer, cure it, sand it to a thin layer and repeat the process a number of times to get a thin, hard protective coating. Varied materials will yield varied results. French polish, for example, is like a skin and allows for lots of vibration but it is not very protective. Hopefully Bruce Sexauer will respond as he uses a variety of finishes and makes responsive guitars.

Best,
Jayne

[redir]

Originally Posted by carmike

...Why doesn't varnish on guitars affect their sound?

It does. It really is part of the instruments tone for better or worse. For better is the thinnest coat possible, for worse, too thick. Most cheap factory guitars have incredibly thick finishes on them and without a doubt it restricts their tone even solid top guitars. They might look fabulous but their sound is severely restricted. On the opposite end of the spectrum many classical guitar builders, and increasingly more steel string builders, are using French Polish which is probably the thinnest finish you can apply. But even that has an affect on tone.

There are trade off's for obvious reasons. A thin FP finish will scratch right down to wood very easily with just a fingernail.

[Osage]

I don't believe either Collings or Gibson use Varnish. Collings uses Lacquer and Gibson uses both lacquer and poly.


As for finish in general, yes, it affects the sound. Builders take this into account when making a guitar. Many builders like it as thin as possible. A completely unfinished Spruce top would not last long under any normal conditions. It's a soft wood and a finish is required to protect it. Both from dings and dents and moisture. Factory guitars often have a somewhat thicker finish than boutique guitars in order to protect them a bit better but even most modern factory guitars have a pretty thin finish.

[bufflehead]

Some of us prefer a satin finish because it is better for the tone. Less muffled than a gloss finish.

[carmike]

That makes sense. I didn't think about the trade-offs with making guitars both sound good and also last a long time.

I suppose the "protective" purpose of bracing has to do with preventing the top from warping, breaking, etc., while the "protective" purpose of the external finish is quite different.

[carmike]

Originally Posted by Osage

I don't believe either Collings or Gibson use Varnish. Collings uses Lacquer and Gibson uses both lacquer and poly.

That could very well be true...I tend to use the word "varnish" to refer to anything that gets slathered on wood. I'll look up the differences between varnish, laquer, poly, nitro, etc.

Collings does offer a varnish finish option:

"How does the varnish finish option compare to the standard lacquer finish?

Varnish is a softer and therefore more flexible finish material. While there are subtle tonal advantages to the varnish finish, this option is not for everyone. Unlike lacquer, the process for applying varnish is not conducive to "finish touch-ups", meaning that we cannot repair some minor imperfections such as small pinholes, bubbles, or sinks. While we've always taken pride in our high standard for fit and finish, we cannot produce varnish instruments to the level of cosmetic "perfection" as we can with our lacquer finish instruments. The varnish finish has a beautiful, rich luster, but may include very small imperfections when put under close examination.

Additionally, the softer finish is not as protective as the harder lacquer finish. The alkyd resin-based varnish finish is very slow to cure and can be relatively soft on new instruments. The finish will continue to harden as the instrument ages, but new varnish instruments can be vulnerable to scratches, dings, and imprinting. By its very nature, varnish can shrink, wrinkle, and/or dull over time and is not likely to maintain a "new" appearance as well as lacquer instruments. With that said, the varnish finish allows the instrument to vibrate more freely and can produce a more responsive instrument with a greater depth of tone."

From: https://www.collingsguitars.com/faq/acoustic-guitars/

[Bruce Sexauer]

Varnish does effect the sound of a guitar. Dramatically.

Finishes have weight, and they have structure. Harder finishes have more rigidity, which is structure. Thicker finishes have more weight in proportion to their thickness. Both structure and weight serve to limit a guitar’s ability to respond to the very limited energy of the string’s movement.

The finish protects the instrument from moisture and dirt, and also can protect the wood from damage due to physical abuse. Thinner softer finishes such as oil varnish are capable of being can enhance the response of a guitar noticeably. Oil varnish handles moisture and grime well, and resists abrasion spectacularly, but does little to ameliorate impact damage such as hitting the guitar top with a pick.

It takes great skill and much more time to apply oil varnish finish as compared to Nitrocellulose lacquer, let alone the modern UV cure finishes. UV finishes can be thinner than most other finishes, but are VERY hard and stiff, which is great for impact damage but not so good for tone and response.

Oil varnish can be evenly applied (important) considerably thinner than nitrocellulose lacquer and weighs less by volume, which is a win/win for response and tone. It is also less structural and allows a less brittle sound which many listeners find relatively beautiful.

[Mr. Jelly]

I have a Waterloo WL-S Deluxe. It is a varnish finish. I had a Waterloo WL-S that had a nitro finish. Other than the finish difference they were built the same. Same woods and the same shape along with the same ladder bracing. I had both of these guitars at the same time. My experience was that there was a big difference in the sound between these two guitars. The nitro guitar was thinner sounding with more fundamentals in the high end. The varnish guitar has a more rounded tone, not as thin sounding and isn't as trebly sounding. I liked them both. The only reason I got rid of the WL-S was because the high e string had a ping sound that I couldn't come to terms with. Plus it moved allot between dry and humid weather. I think my issue might be an individual guitar issue and not something one might find in all of these guitars. I look to getting another one in the future. Especially if I run into an inexpensive used one.

[Bluemonk]

Originally Posted by bufflehead

Some of us prefer a satin finish because it is better for the tone. Less muffled than a gloss finish.

Some prefer a satin finish because it is better for the tone - that may be correct in terms of people's preference, but it is misguided.

Less muffled than a gloss finish - wrong.

[The Bard Rocks]

Originally Posted by Bluemonk

Some prefer a satin finish because it is better for the tone - that may be correct in terms of people's preference, but it is misguided.

Less muffled than a gloss finish - wrong.

This goes along with my own observations. I have been told the big reason for satin finish is that it is cheaper to apply as the wood does not need a filler coat first. I would expect the need for a filler depends upon the type of wood as well.

[Alan Carruth]

If a satin finish confers any benefit, it's probably because it was put on thinner. Gloss finishes need to be really level to look right, and it's hard to get that with a thin coat: it's easier to just slather it on and buff it out. Satin finish is not buffed up, and you can get by with a thin coat if you're careful.

Satin finish is generally the same stuff as gloss, except that it has additive that give it a low surface sheen. The two that I know of are fumed silica and stearates. Fumed silica is, essentially, very fine sand that settles to the bottom of the can. When it's mixed into the finish it also settles out as the finish hardens, making a microscopically rough surface. As the finish dries and shrinks it ends up with a lot of tiny bumps and hollows that reflect light in all directions. Stearates are waxy, and are also mixed into the finish as tiny particles that float to the top. When the finish hardens these little particles of soft material rub off easily, leaving a rough surface. In either case, normal wear can produce a smooth, glossy surface.

[carmike]

Originally Posted by Bruce Sexauer

Varnish does effect the sound of a guitar. Dramatically.

Finishes have weight, and they have structure. Harder finishes have more rigidity, which is structure. Thicker finishes have more weight in proportion to their thickness. Both structure and weight serve to limit a guitar’s ability to respond to the very limited energy of the string’s movement.

The finish protects the instrument from moisture and dirt, and also can protect the wood from damage due to physical abuse. Thinner softer finishes such as oil varnish are capable of being can enhance the response of a guitar noticeably. Oil varnish handles moisture and grime well, and resists abrasion spectacularly, but does little to ameliorate impact damage such as hitting the guitar top with a pick.

It takes great skill and much more time to apply oil varnish finish as compared to Nitrocellulose lacquer, let alone the modern UV cure finishes. UV finishes can be thinner than most other finishes, but are VERY hard and stiff, which is great for impact damage but not so good for tone and response.

Oil varnish can be evenly applied (important) considerably thinner than nitrocellulose lacquer and weighs less by volume, which is a win/win for response and tone. It is also less structural and allows a less brittle sound which many listeners find relatively beautiful.

Thank you for this very helpful reply. My guitar education continues....

[justonwo]

It seems to me that when you say “varnish” maybe you just mean “finish.” Not very many companies use varnish, though it makes an awesome finish. Yes, thickness and finish type do affect the sound.