Finish Types pros and cons - Nitro vs Laquer vs french polish

[ScottKilpatrick]

I see different types listed based usually on guitar builder/company size.

I like Cordoba but would prefer a light finish like nitro but I do not believe large companies offer that. Usually you see nitro and FP offered when guitars are built one at a time i think - correct me if I am wrong.

What is the consensus on tone?

I plan on spending $1000 - $1500 and would prefer a light approach to the top wood for optimized tone.

OK let me have it - am I full of it or is this a legit thing to look for?

Thanks all!

[M Hayden]

Finish can affect tone by adding mass and (potentially) stiffness to the top.

FP is an evaporative finish (soluble in alcohol) which tends to be soft and is sensitive to heat and skin chemistry. It is usually very thin and quite beautiful but it it’s durable. Over time (a long time) it polymerizes and becomes slightly more durable. It is reparable by a skilled finisher.

Nitro is an evaporative finish (soluble in benzene-ring solvents) which is harder than FP bu also susceptible to skin chemistry. It’s also heat-sensitive, and moving a nitro-finished guitar from cold to heat suddenly can cause cracks in the lacquer that are called ‘crazing’. Such crazing is difficult to repair esp if dirt has gotten in the cracks. But it *is* possible for skilled repair people to drop fill and otherwise melt in new finish to repair areas of damage. Over long periods of time, it tends to turn to dust - it doesn’t have extreme longevity.

Polyester is usually a cross linked finished that is not soluble after application. It’s tougher than the other two but it is sometimes thicker and heavier, which some people find detracts from tone. It’s difficult to invisibly repair cracks in polyester finishes since nothing (well, not much) melts into the finish.

I like nitro because of the look and its (relative, mid-term) durability. But none of the other finishes are deal-breakers, either - if the instrument is something I like, the finish isn’t likely to be an issue. I have instruments with FP, nitro, polyester, and varnish, and they all sound like guitars.

[charles Tauber]

Short answer:

Nitrocellulose lacquer is still used by a number of large manufacturers, such as Martin and Gibson, as well as smaller makers. It is sprayed with a high volume of solvent that must then evaporate, a process that continues for months after application. One advantage it has is that, once cured, adding more solvent will soften it, allowing repairs to be made to it. One disadvantage is that it is prone to cold checking - cracking. Nitrocellulose lacquer became popular in the first half of the 1900's, as a much faster, less labour intensive finish than the shellac and varnish finishes that it largely replaced.

Some more modern finishes are urethane-based. The primary disadvantage to them is that they are impervious to solvents, making repairs/refinishing difficult. Some modern finishes are two-part that cure by chemical reaction rather than primarily solvent evaporation.

Some modern finishes are ultraviolet (UV) light cured, cured in a few minutes, greatly quickening the finishing process.

Varnish is a nice finish, as is shellac (French polish). The primary disadvantage of shellac is that it, generally, isn't as tough as other finishes, though some modern variations are more impervious to solvents (alcohol, water and sweat). The primary advantages of shellac are that it can be applied very thin, which is good tonally, and that it can easily be repaired by an expert French polisher. (Finding an expert can be difficult.)

The choice of finish seems to matter less than how well it is applied: any finish can be applied thinly if done expertly. Some factory-applied finishes are applied thinly, others not.

Ideally, one doesn't purchase a guitar without playing it first. In that case, the choice of finish is largely irrelevant tone-wise: the proof is in the pudding, guitar sounding like it does, regardless of the finish applied. If one is buying a guitar without playing it first, there isn't much to go on short of other peoples' opinions and the specifications to which the instrument was made.