With the release of Fender's new Nitro Lacquer Classic Series last week, there have been lots of inquiries about what the differences are between the three mainly used coatings: Nitrocellulose, Polyurethane, and Polyester finishes.
It is our belief that a guitar receives much of its character from its finish. In aim to help you get to know your guitar better, we put together a complete guide on finishes. Although the science behind guitar finishes is heavy in technical content, don’t be alarmed. It is easy to understand. Let’s jump right into it:
Finishes and Wood
A guitar’s finish isn’t as influencing on a guitar’s sound as its wood. But, a guitar’s finish does impact overall health, sustainability and durability. It’s worth noting that a guitar is produced from once-living plant matter; namely, wood. Therefore, since a finish is applied to a substance as sensitive as wood, the guitar finish is also receptive to changes in climate, treatment and age.
Purpose of Guitar Finishes
The principle purpose of a guitar finish is to protect the guitar from external elements. But also, finish does provide slight nuances in the tonal colour of the guitar as well as a personalized visual element.
Nitrocellulose Lacquer was originally developed by DuPont Chemical Company in the 1920s, initially intended for use in the auto industry. DuPont deliberated for it to be used as a sealant against harmful forces caused by nature. Nitro was formerly used in the ‘50s and ‘60s by the music-making industry, although acrylic lacquers were also used at that time.
Polyurethane was invented in Germany in 1937 and was introduced into the music industry in the 1950s. Polyester finishes were first used in the 1970s. Both finishes are plastic based.
Nitrocellulose Lacquer (nitro) is made out of the nitration of cotton. What makes nitro finishes so distinguished is that it is an evaporative finish and mainly that it is very thin. This thin seal does less to get in the way of the natural vibrations of wood, making your guitar sound more open and full-bodied. It allows the guitar’sbody to resonate more and thereby giving it more depth in its tone. Since they are evaporative finishes and also very thin; age, sudden exposure or change in temperature and humidity can cause the finishes to become more brittle. This results in small hairline cracks, called ‘checking,’ and also causes the guitar to yellow. Some guitarists find these characteristics extremely appealing.
Polyurethane and Polyester
Polyurethane allows a glossier and easier and more even finish. In liquid plastic resin form, it made an extremely fast-drying, tough and durable finish (also used for dance floors and bowling alleys) that formed a much harder and abrasion-resistant layer around a guitar than nitro, while still allowing good wood resonance. Further, urethane ages well—it doesn’t check, crack and yellow as nitro finishes do. If you aren’t a fan of the beat-up look, a urethane-finish instrument is probably for you.
The chief advantage of polyester is that it makes for a colorful and extremely tough, durable finish. Polyester guitar finishes age and weather especially well and are seemingly immune to climate and injury—they are highly resistant to scratching and checking, and colors remain remarkably pristine. Sonically, you get tones that are more purely those of the pickups rather than other elements of the instrument’s construction, which many players prefer.