Finishes

[jazzjune18]

Hey. From what y'all have seen. How does a super glossy (nitrocellulose) finish compare to a dull satin finish (ala weber gallatin). I am referring to (1) durability (showing scuffs, etc, and) (2) tone, and volume. Please chime in.

[Marty Jacobson]

Well, it's easier to fix a glossy finish. Satin finishes are almost impossible to restore to "factory condition", or to touch up a small spot without knowing exactly what the finish formulation was, and how it was applied. For a long-term player, I would go with gloss.

Acoustically, there is no connection that I have ever heard of concerning the impact of surface finish on tone. Formulation, maybe... film thickness.. maybe... mass of finished film, sure... flexibility of the coating, etc.

But a reputable builder will make his finish of choice work well with the rest of the system, and a poorly built instrument may not have that attention to detail. So that could affect tone. But it's really about the builder's process, not the finish itself.

[Tom Haywood]

My experience with a satin finish on a Martin guitar is that it doesn't show belt and button rash nearly as much as the gloss finish. This probably applies to most scratches and dings. However, any place that gets rubbed repeatedly, such as the neck and where your arm rubs the top, will become shiny. No way to restore the satin look that I know of. The finishes are the same, except that something is added to the gloss to make it satin, so the thickness should be the same - therefore no difference in the sound.

[sunburst]

There are many finish materials and many finish processes. Common materials used today are nitrocellulose lacquer, various oil varnishes, various spirit varnishes, various catalyzed finishes, various "precatalyzed" finishes, various waterborne finishes, and others. Varnishes can contain natural resins or synthetic resins like phenolic, alkyd, urethane and others. Finishes can be applied by rubbing, brushing, padding, or spraying. Most finishes can be high gloss or less than high gloss. They can be applied thick or thin.
In short, there can be so many differences from one finish to the next, that picking one difference, like the amount of gloss, creates a question with no real answer.
"A super glossy (nitrocellulose)" finish is so different from "a dull satin finish (ala weber gallatin)"... one is buffed nitrocellulose, the other is a modern catalyzed finish of some kind containing a flattening agent... that it is almost "apples and oranges".

About the only way for a finish to noticeably affect sound in plucked instruments is if it is applied unusually thick, in which case it can add undue mass to the top and back with little to no corresponding change in stiffness. (We want a good balance of mass and stiffness for good sound, and changing one without changing the other can upset the balance.) Good quality, well applied finishes have minimal effects on sound, so any differences between them are very small if detectable at all.

[wsugai]

Good quality, well applied finishes have minimal effects on sound, so any differences between them are very small if detectable at all.

John, if this is the case, why do people make such a to-do about varnish over lacquer finishes?

[sunburst]

John, if this is the case, why do people make such a to-do about varnish over lacquer finishes?

Good question!
If I had to sum it up with one word, it would be... marketing.

[Michael Lewis]

It seems that folks are happy to perpetuate partial truths as THE TRUTH. Since most varnishes are applied to instruments in a thin film they add very little mass or weight to an instrument, so they can allow the instrument to sound pretty good by not damping it. but too much varnish would definitely weigh the plates down and damp a lot of frequencies in the structure. SOME lacquer finishes are applied rather thicker than necessary to make them look good and that can add some damping, but not all lacquer finishes are thick. So, a thin varnish finish is better than a thick lacquer finish, but that doesn't mean that all varnish finishes are better than all lacquer finishes. Also there are several other attributes to each type of finish that are considered pluses or minuses for one reason or other, like resistance to wear, UV exposure, moisture, abrasion, heat, etc. There ain't nuthin' perfect.

[8ch(pl)]

Flat finishes will hide very small defects better than gloss finish will. They can also get a bit grubby looking and then be almost impossible to clean. I had to refinish the top of my first Mid Missouri for this reason. I put a Cumberland Acoustic Armrest on the instrument after that and then bought a MCclung armrest when I purchased my second Mid Missouri.

[Brett Byers]

"A super glossy (nitrocellulose)" finish is so different from "a dull satin finish (ala weber gallatin)"... one is buffed nitrocellulose, the other is a modern catalyzed finish of some kind containing a flattening agent... that it is almost "apples and oranges".

I would like to state for the record that our finishes at Weber are strictly Nitro Lacquer or Oil Varnish. No modern catalyzed finishes. I personally hand mix every batch of satin nitro lacquer myself, 16 oz. at a time.

With that being said, John Hamlett is one of the most knowledgeable luthiers around, especially in regards to finish. Everyone, including myself, is well served by his immense contributions to this site. I just felt it was necessary to address that minor technicality.

[peter.coombe]

I once measured the thickness of the varnish finish I use on my mandolins and the nitro lacquer I use on my guitar bodies. The lacquer is more than twice as thick as the varnish. Not only that but I can easily fold the varnish film in half without it breaking. Could not quite do that with the lacquer film. I'm sticking with varnish on mandolins.

[sunburst]

Thanks for setting the record straight, Brett. I was thinking Kim Breedlove had said "they" were spraying Fullerplast (remember Fullerplast?) in Montana (when Flatiron was still there) when it was like -20 degrees with no problems. I guess I made the assumption that Weber was still using some sort of catalyzed replacement for Fullerplast all these years later.

[Nevin]

Back to the original question; nitro cellulose can be finished satin or gloss. If you just don't take it as far in the polishing buffing stage it will be satin. Catalyzed finishes can be made satin but may require an additive. If a satin finish gets polished by use, it can usually be returned to satin using very fine steel wool or micro mesh pads. I like the look of a satin finish with more polished wear marks myself.

[calgary.fiddler]

Good quality, well applied finishes have minimal effects on sound, so any differences between them are very small if detectable at all.

Honestly I don't think this is totally true, I must say I have tried a large number of bourgeois guitars all back to back and then I tried one which was finished with a varnish finish (as oppose to the standard nitro gloss finish) and the difference was huge (to me at least, I'd say I have a pretty good ear for tone response). The big difference was in the overtones. The varnish finish just had extra overtones and extra complexities and colour that none of the other 6-7 bourgeois I had just played. Now the varnish finish did cost $2000 more than the same model with the nitro gloss finish, so was the sound $2000 better? Not even close.

Unless you are looking for the best sounding instrument possible and are overflowing with money I would definitely say skip the varnish.

[sunburst]

Back to the original question; nitro cellulose can be finished satin or gloss. If you just don't take it as far in the polishing buffing stage it will be satin. Catalyzed finishes can be made satin but may require an additive. If a satin finish gets polished by use, it can usually be returned to satin using very fine steel wool or micro mesh pads. I like the look of a satin finish with more polished wear marks myself.

A true less-than-high-gloss lacquer finish (satin, flat, matt, eggshell, whatever) requires adding a flattening agent to the material (as Brett does, 16 oz at a time), same as other finishes. Flattening agents can be added to nearly any finish in nearly any ratio for nearly any surface gloss. Scratching a gloss finish with steel wool, micromesh, etc. can approximate the look of a "satin" finish, but it is not the same.

[sunburst]

Honestly I don't think this is totally true, I must say I have tried a large number of bourgeois guitars all back to back and then I tried one which was finished with a varnish finish (as oppose to the standard nitro gloss finish) and the difference was huge (to me at least, I'd say I have a pretty good ear for tone response). The big difference was in the overtones. The varnish finish just had extra overtones and extra complexities and colour that none of the other 6-7 bourgeois I had just played. Now the varnish finish did cost $2000 more than the same model with the nitro gloss finish, so was the sound $2000 better? Not even close.

While you are basing your conclusion on a sample size of 6 or 7 guitars, I'm basing mine on the the 30-some-odd mandolins I've built and finished in various finishes. I hear no dramatic difference that I can attribute to the finish material I've applied, and in fact I don't really hear any difference in the sound that I can attribute to the finish. Now, 30-some mandolins is not a very big sample size for a scientific experiment, and my own personal conclusion (not a double blind test by any means) is not scientific evidence by any means, but when we consider what a finish is and what it does, any contribution to sound must come from the added mass of the finish on the instrument and/or any effect it has on the stiffness of the parts of the instrument. The thinner the finish film, the less of either effect it can have, so we apply finish in thin films to minimize it's effect (if we value quality over production, that is). When we minimize the effect by applying finish thinly, we minimize any difference in the finish's effect on the sound of the instrument.

If Peter Coombe has measured his finishes and found his lacquer film to be twice as thick and his varnish film, it seems to me that, if he is hearing a difference between the two, we could just as easily attribute it to finish thickness as finish type.

[Charlieshafer]

Too true. The other problem involved here is that instrument-to-intsrument comparisons never work out as the basic tone of the guitar body or top (also applied to mandolins, of course) will change from one instrument to the next, regardless of finish. The only way to tell would be to finish the same body in one, take it off, then try the other finish. Ooops, that won't work as when you remove one, you'll take off just enough wood to change the tone. I would be curious to know of the oil/varnish finishes we use on furniture would work for instruments. Very thin film build up, infinitely re-touchable with little effort (and invisible, with just a little skill) and somewhat water resistant. The downsides of this could potentially be the lower wear resistance (but then, it's easy to re-touch) and you can't buff to a gloss finish. A really pretty sheen, yes, but not gloss. The mix can be about 1/3 mineral spirits, 1/3 tung oil, and 1/3 varnish (not polyurethane varnish). We've also been experimenting with a couple of newer pre-mixed hard wax/oil mixes with very good results, like the Fiddes.