Nitrocellulose Lacquer Vs Polyurethane: Choosing A Finish For Your Guitar

Nitrocellulose Lacquer, or nitro for short, is a paint lacquer that can give any guitar a classic vintage look.

The beauty of a nitro finish isn’t hurt by a little bit of time either. That’s because, while this finish can yellow with age, it doesn’t leave your guitar looking dated.

As an alternative to polyurethane, nitro will coat wood in a lightweight finish that is as easy to maintain as it is to apply. And it layers on so thinly, it feels ‘barely-there’, compared to a polyurethane top coat.

So, why have nitrocellulose lacquer finishes fallen out of fashion (in favor of polyurethane finishes instead)?

Polyurethane is more durable and less likely to chip than nitro lacquer finishes. And, more importantly, polyurethane finishes (either oil based or water based ones) are not as toxic as nitrocellulose lacquers solvent-based solution.

Related Post: Don’t Put Nitro Lacquer Over That Polyurethane Finish [Here’s Why]

The overwhelmingly negative health effects of nitro lacquer has meant that it’s rarely used by manufacturers in mass-production lines (such as car manufacturing).

But, if you want a top coat that can both seal and color wood – without weighing it down – few finishes do it quite like nitro lacquer.

So, in this post, we are going to cover exactly what nitrocellulose lacquer is (and whether or not it is worth the risk). We will also show you how you can check to see if your guitar has a nitro or polyurethane finish.

Plus, we will dive into why a thicker polyurethane finish may be just what your guitar’s tonewood needs instead…

Nitrocellulose Lacquer Vs Polyurethane: Choosing A Finish For Your Guitar

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What Is Nitrocellulose Lacquer Used For?

This lacquer paint is mostly used as a way to give wooden instruments a bold change of color.

Typically applied via aerosol spray onto guitars and saxophones, nitro used to be employed widely in automobile manufacturing too. That is before the health-costs of this toxic paint spray saw it quickly replaced by Acrylic Lacquer paint instead.

What Is The Difference Between Nitro Lacquer and Acrylic Lacquer? Nitro Lacquer is solvent-based, while Acrylic Lacquer is water-based.

What Is A Poly Guitar Finish All About Then?

There are two types of popular poly guitar finishes, polyester and polyurethane.

Polyester is often used as a base coat sealer for a nitro lacquer top coat. It protects the wood underneath while providing an even surface for nitro lacquer to bond to.

Polyurethane, however, is often applied as a top coat. It can be wiped-on (or brushed on a little more thickly). And, it is more durable than either polyester or nitro lacquer.

Related Post: When Should You Use Tru-oil Vs Wipe-On Poly? [3 Key Comparisons]

So, How Can I Tell What Finish Has Been Used On My Guitar?

Nitro coats are much thinner than polyurethane finishes. They look glossy, not plastic like polyurethane. And they are so wafer thin you can feel the wood underneath.

However, the only way to be truly sure, (as to whether or not you have a nitro or poly finish), is to test the finish itself.

How Do You Check A Nitro Finish And Identify If It Is Really Nitrocellulose Lacquer?

By dabbing it with Acetone. Acetone works like a Lacquer thinner, and it can be used to remove both nitro and acrylic paint.

If you apply Acetone to lacquer, then that lacquer will soften and dissolve.

So, select a small but unnoticeable section of your guitar finish and prepare to test it.

  • 1. Get a cotton bud and dip it in Acetone.
Dip a cotton swab tip in acetone.
  • 2. Place it against the unnoticeable section of your guitar.
  • 3. If the finish softens, you have a lacquer finish. If it does not, you have a poly finish.
Press that bud tip onto the small spot on your guitar.

Is Nitro Lacquer Stronger Than Polyurethane?

One of the biggest advantages polyurethane has over nitro, is its durability.

Polyurethane is tough stuff, and is much better than nitro at handling scrapes, scratches and even sunlit UV rays. It is also more water-resistant than lacquer too – as lacquer can be easily damaged by moisture.

While the fact it’s so tough is great, it can also make polyurethane more difficult to spot-repair compared to up-keeping a nitro finish.

Still, because polyurethane is oil-based, (or water-based, depending on your product), it doesn’t bring with it the negative health impact of a nitro paint spray.

Related Post: Can You Put Nitro Lacquer Over An Acrylic Guitar Finish?

Is Nitrocellulose Lacquer Really Bad For The Environment?

Nitrocellulose Lacquer is pretty nasty stuff. So much so, that this is the main reason why it’s fallen from grace as a first-choice paint option.

Nitro is incredibly toxic, and in its aerosol spray form, it is a severe respiratory hazard. It causes a number of health problems from dizziness and nausea, to absolute blackout unconsciousness.

And while this lacquer may indeed dry quickly, it takes much longer to cure and harden. Curing can take up to a month to complete, during which time, nitro lacquer will continue to release dangerous VOC’s into the air.

However, once nitro cures, it becomes non-toxic.

What Are VOC’s? VOC’s are Volatile Organic Compounds. These are the gases found in solvent-based chemicals. As solvents dry and cure, these often times harmful gases are released into the air.

To Wrap Up, Is Nitro Better Than Polyurethane (Or Vice Versa)?

Nitro finishes are much thinner and less restrictive than polyurethane coats.

Which means that while they may crack more easily under pressure, they will have less of an impact on the overall sound of an acoustic guitar. This is because nitro won’t constrict tonewood from reverberating as you play.

But, polyurethane lasts longer, and it does a much better job at protecting your instrument. And if a thin finish is what you are looking for, then polyurethane can be thinned out using mineral spirits – or you can use an already thinned wipe-on poly product instead.

So, choose polyurethane over nitro. This is because a thinned polyurethane top coat will give you the near-weightless benefit of a lacquer coat… without any of those toxic nitrocellulose fumes.

References

Gas and water permeability of poplar wood coated with sealer and nitrocellulose lacquer, polyester lacquer and nano-particles. (cabdirect.org)

Comparison of six ester components in nitrocellulose lacquer thinner from the aspects of dissolution rates, explosion characteristics and environmental influence – ScienceDirect