What Is Nitrocellulose Lacquer?

Nitro vs. Polyester: What's the Difference?

Beginning in the late 1960s and early 1970s, most large guitar manufacturers transitioned from nitrocellulose lacquer to polyester (or polyurethane) finishes. The reasons were largely economic: polyester is cheaper to apply, dries faster, requires less labor, and creates a harder, more durable coating in fewer coats.

The tonal argument for nitro is that it is applied in very thin coats and remains slightly flexible throughout its life, theoretically allowing the wood to resonate more freely. The practical argument for nitro is that it ages beautifully — checking, crazing, yellowing, and wearing through to the wood in ways that signal authenticity and provenance. Polyester finishes are thick, hard, and do not age in the same way.

How to Identify a Nitrocellulose Finish

You can often identify a nitro finish by several characteristics:

• ›Checking: Fine hairline cracks in the finish, especially in the lacquer over binding or in areas prone to temperature change
• ›Checking pattern: On vintage guitars, checking appears as irregular, random cracking — distinct from the 'alligatoring' of worn polyester
• ›Smell: Rub the finish with your thumb and smell — genuine nitro has a faint chemical (acetone-like) smell when warmed
• ›Solvent sensitivity: Nitro will soften and melt when exposed to acetone or nitro-based products. A drop of acetone on a hidden area will immediately cloud a nitro finish
• ›Thickness: Nitro is typically applied in many thin coats; polyester is applied thicker. Vintage nitro finishes are often only 3–6 thousandths of an inch thick
• ›Edge wear: Nitro wears naturally at strap buttons, fret ends, and high-contact areas, exposing bare wood. Polyester tends to chip rather than wear

Checking and Aging on Vintage Guitars

The checking pattern on a vintage nitro finish is one of the most prized visual indicators of authenticity and age. Checking occurs because nitro finishes contract with temperature and humidity changes at a different rate than the wood beneath. Over decades, this creates fine cracks in the lacquer — sometimes called 'weather checking' or 'lacquer checking.'

Different checking patterns are associated with different production eras and storage conditions. A vintage guitar that has spent time in environments with large temperature swings will show heavy checking; one stored consistently may show little or none. Neither is more or less authentic — checking tells a story about where a guitar has lived.

Refinished vs. Original Finish

In the vintage market, original factory finish is extremely important. A guitar with original nitro finish — even if worn, cracked, or faded — is worth significantly more than a refinished guitar. Refinishing, even with nitro, destroys the original patina and reduces collector value by 30–60% or more depending on the model.

To identify a refin: look for overspray in pickup routes and hardware cavities, inconsistency in checking patterns (refins often have checking that doesn't penetrate to earlier layers), and the overall uniformity that tends to come from a relatively recent finish application compared to authentic 60-year aging.