Choosing Shellac vs. Lacquer vs. Varnish vs. Polyurethane

By MWB-Team •  Updated: 06/22/23 • 

If you’re looking for a top coat to finish your wood surfaces, shellac, lacquer, polyurethane, and varnish are the most commonly applied to wood surfaces. However, each of these finishes has its pros and cons, which affect its durability, application, usage, and much more. In this article, we’ll review these four finishing options to help you make an informed decision.

Shellac

Shellac is an interesting wood finish that has been around through the years and is still being used extensively as a wood finish. It is a natural finish made from dried secretions of the lac bug. Once the secretions are collected, they are strained to remove impurities and dissolved in a solvent such as alcohol to be used as a finish.

A shellac wood finish dries when applied to a wood surface as the solvent evaporates. In natural form, shellac wood finish has an orange or amber color, but it is also sold in a variety of colors.

Shellac Wood Finish On a Guitar Body

Shellac Wood Finish On a Guitar Body

Apart from the colors, shellac wood finishes are available in only a gloss sheen. However, you can use a steel wood #0000 grit or a flattening agent to flatten it.

While shellac is a reasonably durable finish, it does have some drawbacks. First, a white ring can develop if you place something hot under it. Second, because it is soluble in alcohol, any alcohol spillage will start to dissolve away a shellac finish. Read more about shellac wood finish.

Lacquer

Lacquer wood finish has been around since the 1920s and was introduced as superior to shellac. Most lacquers are nitrocellulose-based, made by treating cellulose fiber in cotton and wood fibers with nitric acid. Resins are then added to the nitrocellulose binder to improve its flexibility.

When applying lacquer, there are two main types. First, there are those that dry as the solvent evaporates, then there are those that dry through chemical reactions called catalyzed lacquers.

Lacquer dries in different sheens, from matte to very high gloss. Of all the wood finishes, lacquer has the fastest drying time, which makes it possible to apply different coats in a shorter time frame.

Mahogany Dining Table With  Pre Cat Lacquer

Mahogany Dining Table With Pre Cat Lacquer

Apart from the fast drying times, a lacquer wood finish is also more forgiving of mistakes, so you can easily repair it. It is also very clear, which makes it a good option if you want to protect and show off the beauty of wood. Unlike shellac, lacquer is also resistant to water, heat, alcohol, acids, and alkalis.

Most of the lacquer problems are usually a result of the application. Blushing, fish-eyeing, and other problems result from spraying it (Read spray lacquer problems). However, it is also more toxic, flammable, and has reduced protection compared to film-building finishes like varnish and polyurethane. Read more about lacquer wood finish.

Polyurethane

Polyurethane finish is a type of varnish, but it is harder, more rigid, and has less oil in it. Of all wood-finishing topcoats, polyurethane is the hardest and most durable. It has grown in popularity and has become one of the most popular go-to finishes for most woodworkers.

Most pure polyurethane finishes are available in two parts, and they cure by absorbing moisture or heat. The polyurethane you commonly use and widely available is a varnish (Alkyd Varnish) modified with a polyurethane resin, an alkyd, to make one-part polyurethane.

Mixing Two Part Polyurethane

Mixing Two Part Polyurethane

Poly comes in two major types, which are oil-based and water-based. Oil-based polyurethane has been around for longer, while water-based polyurethane is newer and presents some advantages over the oil-based variant.

Oil-based poly dries more slowly, about 48 hours, and takes even more time to cure completely. On the other hand, water-based polyurethane has a quick drying time of about 2 hours. Water-based polyurethane also dries to a crystal clear appearance that does not change with time and has lower VOCs.

Polyurethane can be applied using a brush, roller, spray, or wipe-on. Wipe-on polyurethane is the best for beginners because it’s easier to apply and gets better results. However, when wiping on polyurethane, you’ll require more coats because it is thinner to allow for better leveling.

Varnish

Varnish, including polyurethane, is another protective and durable wood finish commonly available. It is made by cooking Alkyd resin with different oils, which is the most popular and cheaper way of producing varnish. Because varnish does not cure fast enough, metallic driers such as cobalt, manganese, and zinc salts are used.

Varnish finishes resist water, heat, wear, solvents, acids, and alkalis. This is because their cross-linked resin molecules are harder to break apart or for water or vapor to pass through. It takes high heat, sharp force, or stronger solvents and chemicals to damage varnish finishes.

Applying Spar Varnish to Adirondack Rockers

Applying Spar Varnish to Adirondack Rockers

Varnish is also excellent for outdoor use compared to other finishes because of its properties. For outdoor use, the varnish is cross-linked to an oily resin, making it more flexible to expand and contract with temperature and as the wood moves. This type of varnish is called Spar varnish, and when mixed with a polyurethane resin, it is called Spar urethane.

Which is Better to Use?

Fastest Drying Time

The fastest drying of these finishes is lacquer, which can take about 30 minutes to fully dry. Shellac comes in second and can take up to one hour to fully dry. For polyurethane, water-based polyurethane dries in about two hours, while oil-based polyurethane takes about 24-48 hours. Varnish has the longest drying time of about 24-48 hours, but it can take less time with metallic driers added.

Easiest to Apply

The easiest finish to apply of all these finishes is wipe-on polyurethane. It is very beginner friendly and very easy to apply without making mistakes. Wipe-on varnish is also easier to apply, like wipe-on polyurethane.

Easiest to Repair

Lacquer is the easiest finish to repair and is very forgiving of beginner mistakes. When sprayed with another coat, the previous coat is slightly dissolved and blends with the topcoat perfectly.

Most Durable Finish

Polyurethane is the most durable of all these finishes when applied to wood. It can handle abrasive damage, acids, heat, moisture, and other elements. Catalyzed lacquer is also a very durable finish when applied correctly. However, it is harder to apply catalyzed lacquer for beginners. See our guide on polyurethane vs lacquer for table-top.

Best for Outdoors

Varnish is the best finish for outdoor wood projects such as furniture and other projects. Spar varnish and spar urethane are flexible finishes that will expand and contract with temperature changes. This makes them ideal for outdoor use because they can better resist cracking or peeling. Check out our best exterior polyurethane.

Best for a Crystal Clear Finish

Water-based polyurethane is your best bet if you’re looking for a crystal clear finish that does not yellow even with time. Water-based poly has a milkfish appearance when in the can, but it dries into a crystal-clear coat that does not change even with time. Lacquer is another option you can choose that yellows slightly with time. See our best clear coats for painted kitchen cabinets.

MWB-Team

Hello there! This is the Make Wood Better Team. Here, we share informative how-tos and guides focused on making wood better. Whether it's finishing wood, maintenance, or restoration, there's something on this website for you to learn and improve your skills.