Wood detailing: choosing between varnish and lacquer

Wood detailing: choosing between varnish and lacquer
Photo: Pixel1, Pixabay

One of my favourite guitars of all time is the classic Fender Stratocaster and there’s this one particular reissue that is finished in a unique shade of green referred to as sea-foam green that in my opinion looks absolutely gorgeous. This one particular model caught my eye when the lead vocalist of one of my favourite bands, New Jersey-based Real Estate, played this guitar when I saw them playing the Laneway Festival back in ’13.

The finish on a guitar might not always be an important consideration when you’re picking a guitar but generally, when it comes to other wooden products, finish is an essential factor, both aesthetically and functionally. In the guitar for example, the type and the thickness of the coat finish can affect how it sounds, which is why it’s important to measure the applied thickness using devices such as an Elcometer to ensure you’re getting the result you’re looking for.

Types of coat finish for wood

Depending on what it’s used on, there are a lot of types of finish you could apply on a body of wood. In guitars, the type used range from simple varnish and lacquer to newer and more complex materials such as polyurethane and polyester. On hardwood furniture and floors, you could use rub-in oils, varnishes, oil-varnish blends, waxes or lacquers. The differences between each finishes tend to be subtle and might not be obvious immediately but if longevity is an important factor, careful considerations are required.

In this discussion, I’m going to dig deeper into the two most common coats available, varnish and lacquer.

Varnish coats to showcase the natural quality of the wood

Referring to varnish as a coat finish is a bid of a misnomer since technically, the term varnish itself refers to the clear, transparent and well-varnished look of the product. The word varnish doesn’t refer to any specific chemical material used to achieve this look and could very well be used on any kind of solution that could achieve that effect, which includes lacquer as well. It’s a bit confusing but in modern practice and for the purpose of this discussion, I’m referring to a combination of resin, drying oil and thinner or solvent.

Due to its transparent quality, varnish is effective when the intention is to visibly show the natural tones and grains of the wood itself. The finish has a glossy look by default but for those looking for a more natural sheen; it is possible to add flatting agents in order to create a satin or semi-gloss look. Varnish is easy to apply and that brushstrokes aren’t as visible with varnish as it is with other finishes, which enhances the natural look of the coat.

Other than their aesthetic quality, varnish also provides a protective film, which makes the surface more resistant to wear and damage and provides a natural UV light protection. However, the varnish coat itself can turn dull or yellow over time when excessively exposed to sunlight and that unlike James Bond’s martinis, they should be stirred, not shaken or you risk bubbles forming when you’re applying the finish.

Lacquer coats and their high range of sheen levels

The word lacquer refers to a collection of quick-drying and solvent-based coating. In terms of coating finishes, it refers to polymers such as nitrocellulose or nitro for short and/or acrylic compounds dissolved in a mixture of volatile solvents, commonly referred to as lacquer thinner. Nitro lacquer for example is commonly used in guitars and unlike varnishes which are commonly applied with a brush; lacquer is formulated to be sprayed on.

In contrast to the glossy clear look of varnish, lacquer is versatile in that it can be clear or coloured with a range of sheen ranging from flat, matte, satin, semi-gloss and gloss. True to its quick-drying nature, lacquer can dry as quickly as 15 minutes in room temperature while varnish could take more than 24 hours to properly dry. As such, if you’re applying more than one layer of coating, lacquer finishes would enable you to finish your work within a day compared to varnish.

In terms of protective quality, lacquer is tougher than varnish, which provides protections from acid, water and abrasions due to the existence of plasticiser. Additionally, lacquer finish doesn’t suffer from the same yellowing problem seen in varnished and other types of coating. However, the application of lacquer itself needs to be done in a controlled environment, as low temperature can cause orange peel problems while high temperature may cause bubbles to form.

Choosing between varnish and lacquer

If durability is a concern of it revolves around something that will have to suffer from extensive wear & tear, like a guitar for example, lacquer is the preferred choice. In addition to their durability, lacquer finishes are easy to repair and work on while varnish would require the use of mineral spirits to clean up. The downside is that even clear lacquer will never able to match the look of varnish when applied correctly and that varnish is much less flammable than lacquer, which makes applying varnish both easier and safer.