Types of Guitar Finishes: Nitro vs Poly & More

As meaningless as it is, we guitarists like to obsess over a guitar’s looks. We want guitars that match our style and tastes, guitars that excite us and encourage us to play. For many, that means finding a guitar with the right finish. And though we tend to focus more on color, the type of finish used is just as if not more important. 

Throughout the history of the guitar, there have been numerous different types of guitar finishes. Each of these has its own look, wears differently, and has its own pros and cons. In this article, we’re going to look at the different types of guitar finishes, their history, and why you might or might not prefer one type of the other.

Oil and Wax

It shouldn’t be surprising that oils and waxes are some of the first guitar finishes ever used. Prior to the advent of electric instruments, everything was acoustic. Since acoustic instruments rely on the woods in the instrument resonating fully to create the tone, finishers needed to make sure their finishes didn’t dampen the instrument. Oils and waxes are perfect for that because they’re lightweight and have little effect on the tone or EQ of the instrument. 

There were a variety of different formulas and methods used over the years. For example, glair—a mixture of sugar, honey, egg white, and sometimes gum arabic used to paint—was also used to finish lutes for decades and can still be found on some modern instruments. For guitars though, finishers preferred different combinations of oils and or waxes. 

Advantages 

So in 2023, why would you want to use oil and wax finishes on a guitar? One big reason is aesthetics. Oil and wax finishes have a distinct, minimalist look. They tend to be plain with a waxy matte finish, while also bringing out the natural wood grain. These finishes can be a great option if you like a low-key finish that lets the wood grain be the focus. 

Another reason these finishes still get used today is feel. Contrary to what you may assume, these finishes don’t feel waxy when done properly. Oil and wax based finishes are lightweight and almost make your guitar feel like it’s bare wood.  Many players really like the slim and natural feel that comes with oil and wax finishes.

Lastly, oil and wax finishes don’t have much impact on tone or EQ. That means your guitar can resonate to its fullest and produce the best sounds possible. If you are a tonal purist and have an acoustic guitar with incredible tonewoods and construction, a minimal oil and wax finish might be a great option. 

Disadvantages

As you might expect, there are some big disadvantages to using the older oil and wax finishes. The most notable disadvantage is that you don’t have much protection. If you drop your guitar or bump it into something, you will definitely dent or scratch the wood. Unlike thicker and sturdier finishes, oil and wax finishes offer almost no protection against drops, bumps, and scuffs. 

Another disadvantage is that they may require more maintenance than other finishes. Wax finishes for example often require you to apply more wax every so often. This isn’t a huge deal, but it can be annoying if you play your guitar a ton and have to apply wax more often. 

The other big downside is that oil and wax finishes are limited in terms of style. You can’t turn your guitar lime green or turquoise with oil and wax. Oil and wax finishes bring out the natural wood, which may not look great depending on the guitar. However, this can be an advantage too depending on what you’re looking for. 

Shellac

After oils and waxes, shellac was the next type of finish developed for guitars and other instruments. Shellac is actually a natural resin that comes from a bug native to Thailand. As the guitar took off in the 20th century, shellac applied with a rag (referred to as “French polish”) became the dominant guitar finish. Martin even used shellac for over 100 years, so it clearly was a good option. It was particularly desirable for classical acoustics due to how thin it is. 

Shellac is similar to oil and wax finishes in many ways, but with much more protection. It gives a clear, glassy coating that protects the guitar from more scratches and bumps than oil and wax. It is also very thin, having minimal impact on the guitar’s tone. 

Advantages

The biggest advantage of shellac compared to oil and wax finishes is that they provide more protection. Shellac is tougher than oil and wax, so it helps keep the guitar more secure. Shellac can prevent some minor bumps and scratches from getting into the wood. 

Shellac finishes can also look incredible when done right. They bring out the natural wood grain just like oil and wax finishes, but with a glassy sheen that can really make the guitar look great. If you like a more minimalist look but want a bit more protection than oil and wax, shellac can be a great option. 

One last pro of shellac finishes is that they don’t have much tonal impact. They are a bit heavier than oil and wax, but they still have little effect on tone. Shellac finishes will allow your guitar's natural sound to be heard clearly. 

Disadvantages 

All that said, shellac has downsides too. Like oil and wax finishes, shellac limits your aesthetic options. They only bring out the natural look of your guitar, so you’ll want to try something else if you want a vibrantly colored guitar. 

Another con of shellac is protection and durability. While they do provide more protection than oil and wax finishes, they still don’t provide as much protection as some other finishes. The other issue is body chemistry. Just like we discussed in our article about sweaty hands, everyone has slightly different body chemistry. Certain people can have issues with shellac dissolving due to their body chemistry. 

Nitrocellulose Lacquer (Nitro)

Nitrocellulose lacquer, commonly known as nitro, was an incredibly common finish during the 50s and 60s. Though most people know the story of Leo Fender using nitro finishes to replicate the car finishes of the 50s and 60s, nitro finishes first came about in the 20s. Nitrocellulose was first created by DuPont in the 20s as the first spray-on paint, and it quickly got used on guitars. Guitars of the 20s and 30s commonly had a nitro finish, providing a high gloss finish. 

The exact types of nitro used in the 20s and in the 50s/60s are a bit different, but they both provide a similar finish. The result is a thin, slick, and glossy finish that looks great and to some, sounds better than most other finishes. Though nitro isn’t commonly used today, Gibson and Fender still use it for many of their vintage-styled custom shop offerings. 

Advantages

Nitro is arguably the most sought after finish, so it clearly has a lot to offer. As mentioned before, the biggest advantage of nitro to many is the tone. It is more porous than other finishes, leading many to believe that nitro results in a more open sound with more sustain. That said, these sorts of claims can be harder to prove, and many believe that how the finish is applied is a bigger factor when it comes to tone. 

The other big advantage (or disadvantage) of nitro is how it wears. Nitro finishes wear in a very distinct way over time. They can start to crack a bit after a few years, especially when taken on the road. They also scratch and ding very easily, making them look worn pretty quick. They’ll start to yellow as well given enough time and exposure to light. On top of that, it also wears away over time. When you see those classic iconic guitars from the 60s with the finish worn away where the arm rests, that’s because of the nitro finish. Many absolutely love the road worn nitro finish look, so they have become desirable for their grungy style. 

Disadvantages 

Like all types of guitar finishes, nitro isn’t perfect. One potentially big downside is that nitrocellulose can be toxic. While you’re fine playing a guitar with nitro, it can be a hazard to work with. It’s flammable and requires a mask when applying, so it can be a bit of a hassle to do yourself if you aren’t very experienced. 

The only other real downside is wear. Though many love the way nitro finishes wear, others prefer their guitars to look new as long as possible. Since nitro cracks, chips, yellows, and wears away over time, it’s not a good choice if you want your guitar to look new for years to come. 

Polyurethane (Poly)

Polyurethane finishes, referred to as poly, are the modern standard for guitars. If you walk into a guitar shop and pick up a random guitar, chances are it has a poly finish. It is a plastic, urethane-based finish that became popular in the 1950s. It quickly caught on as a guitar finish due to being cheaper, easier to apply, and safer than nitrocellulose, as well as providing more protection. 

There’s a lot of variety when it comes to poly finishes. There are thin, satin poly finishes, and there are thick, glossy poly finishes. Poly finishes come in a full range, from cheap and low quality to expensive and stunning. Between low-end beginner guitars to high end custom guitars, poly is used for the majority of guitars today.

Advantages

The biggest advantage of poly finish, other than being cheaper and easier to work with, is their durability. Poly finishes are thicker with a plasticky sort of look that provides the most protection out of all the finishes listed here. Though it still won’t protect against drops and deep scratches, it will give you the best protection possible. It also holds up very well over time and doesn’t wear and crack like nitro finishes. If you want a guitar that looks new for decades, poly is undoubtedly the way to go. 

Disadvantages 

The downsides of poly finishes depend on the quality of the finish. Lower quality poly finishes may not be as protective or good looking as high quality poly finishes. However, those can be avoided by purchasing guitars with more well done finishes. 

Another potential downside is the lack of wear. For players who want a relic sort of look and want a guitar that ages over time, poly will leave you disappointed. At the same time though, this could be advantageous if you don’t like worn looking guitars. 

Lastly, some say that nitro finishes dampen the guitar's tone and sustain. As before, these sorts of claims can be hard to prove, and it’s doubtful that most listeners could even tell the difference. Still, it’s something worth considering if you are in pursuit of the best tone possible. 

Polyester

Though often seen as a forgotten finish failure of the 70s, polyester isn’t as bad of a finish as people think (and is still used today). Guitar manufacturers started using polyester finishes in the 70s, mainly because they are even stronger than polyurethane and dry faster. However, people quickly voiced their dislike for polyester finishes. They claimed it was ruining their tone since it was too thick. So what was going on?

There are two factors at play here: changes in spec and a lack of change. First off, polyester finishes require slightly different processes to be applied as best as possible. At first, guitar manufacturers like Fender didn’t change their methods, leading to some less than optimal finishes (though techniques have since improved). On top of that, Fender was also changing many guitar specs at the same time, causing people to believe the finish was the blame. However, the real big tonal change was from the change in specs. 

Advantages

Polyester’s main advantage is durability. It is even more durable than polyurethane finishes, standing up to a lot of use and abuse. They are thick and strong, making them arguably the best choice if you want your guitar to look as new as possible despite tons of use. 

It’s also a relatively cheap finish that can be applied faster. For manufacturers, that means they can save some time and money. That can translate into savings for the buyer of the guitar as well. 

Disadvantages 

The only real disadvantage of polyester finish is tone, if you believe it has a big impact. Though the decrease in tone quality from Fender in the 70s is likely due to the change in specs, many still believe that heavy polyester finishes ruin the tone. Again, these claims are hard to prove, and it’s likely that polyester has a minimal impact on tone. 

The other potential disadvantage is lack of wear. Like with poly finishes, polyester doesn’t really yellow, crack, or age. If you want a road worn guitar, you’ll want something other than a polyester finish. 

Conclusion

Though types of guitar finishes may not seem like the most exciting topic, finishes can have a big impact on how your guitar looks, ages, and sounds. Different finishes have different looks, durability, and impact on tone. When buying your next guitar, take a moment to consider the type of finish and what you’re looking for in a finish—whether that be durability, tone, looks, or ability to age over time.