Types of Varnish: Comparing the Main Options

Walking into a hardware store looking for varnish can be confusing, since shelves are usually stocked with several different formulations, each with its own strengths, drawbacks and recommended uses. This page breaks down the main categories to make that choice easier.

Oil Based Varnish

Oil based varnish is one of the traditional options, built around natural or synthetic drying oils combined with resin. It tends to penetrate wood fibres well, producing a warm, slightly amber tone that many people find attractive on hardwoods. It is generally durable and reasonably forgiving to apply, but it dries more slowly than other types, often requiring a full day or more between coats, and it usually involves solvent based cleanup for brushes and tools.

Water Based Varnish

Water based varnish uses water as its main carrier instead of solvents. It dries faster than oil based varnish, has a much lower odour during application, and cleans up easily with soap and water. It also tends to stay clear rather than yellowing over time, which makes it a common choice for light coloured woods where keeping the natural, pale tone is important. The tradeoff is that some water based products are less durable than oil based or polyurethane options, particularly on high traffic surfaces, although formulations have improved considerably over time.

Polyurethane Varnish

Polyurethane varnish is a popular choice for floors, tabletops and other surfaces that need strong resistance to scratches, impact and chemical spills. It is available in both oil based and water based versions, combining the toughness polyurethane resin provides with the drying characteristics of its particular base. Because of its hard wearing nature, it is frequently recommended for wooden flooring and furniture that sees daily use.

Spar Varnish

Spar varnish, sometimes called marine varnish, is formulated specifically for exterior use and for wood that will face constant exposure to sun, rain and temperature changes, such as boats, outdoor furniture and exterior doors. It is designed to remain flexible rather than fully rigid, which allows it to expand and contract with the wood as moisture levels and temperature change, reducing the risk of cracking. Spar varnish usually contains additional ultraviolet filters to slow down the fading and breakdown that sunlight causes.

Shellac Based Finishes

Shellac is a natural resin based finish that dries quickly and produces a warm, glossy look. It is less water and heat resistant than polyurethane or spar varnish, so it is more commonly used on furniture and decorative pieces kept indoors rather than on surfaces exposed to moisture or heavy use. It can also be layered and repaired more easily than some synthetic varnishes, which makes it useful for restoration work.

Gloss, Satin and Matte Finishes

Within most of these categories, varnish is also sold in different sheen levels, typically gloss, satin and matte. Gloss finishes reflect the most light and tend to highlight the depth of the wood grain, but they also show scratches and dust more readily. Matte finishes are more forgiving of surface imperfections and give a more understated look, while satin sits in between the two. The choice of sheen is largely a matter of appearance and practicality rather than durability, although some matte formulations achieve their look with additives that can slightly affect wear resistance.

Matching the Type to the Job

As a general guide, floors and heavily used furniture benefit from polyurethane varnish because of its hard wearing surface. Exterior wood exposed to sun and rain does best with spar varnish because of its flexibility and ultraviolet protection. Indoor furniture and decorative pieces where colour and finish quality matter most can suit oil based, water based or shellac finishes, depending on how much time is available for drying and how light or dark the final colour should be.

Reading the manufacturer's guidance on a specific product remains important, since formulations and recommended uses can vary between brands even within the same broad category.