One of the biggest questions of any project is how to select the correct finish.
What’s the difference between Polyurethane, Varnish, Oil, Shellac, or Lacquer?
Does Wax work as a final finish?
What’s the difference between water-based and oil-based Polyurethane?
The last thing you want to do is finish a beautiful piece of furniture and then have it wear out in a year. You could spend all day reading and talking about the chemistry at work in the wide variety of finishes, but the more practical application is simply when to use what kind of finish.
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So here is a basic guide on how to select the correct finish for your project.
Oils are one of the easiest finishes to apply – simply wipe it on, allow it to penetrate the surface of the wood, and wipe off the excess. They cure very soft and thin and, therefore, do not leave a surface film like many other finishes. Because they do not leave a surface film, oils are also one of the easiest finishes to repair – simply apply more oil when the surface starts to show wear.
Use oils for a soft and natural, unfinished look. Or apply oils beneath a film finish (i.e. varnish, lacquer, etc.) when you need extra durability but still want the natural look.
Common oil finishes:
Polyurethane is one of the most common finishes applied by the average woodworker either over stain or on its own. It offers the utmost protection against wear and tear, heat, water, solvents, and other chemicals. Polyurethane comes in both water- and oil- bases, with options from satin to gloss.
Water-based polyurethane (such as Polycrylic) is low odor, low toxicity, and will not yellow over time like oil-based polyurethane, which makes it a good finish choice for light colors. However, water-based polyurethane does not hold up as well as oil-based polyurethane against heat and chemicals. Use it for furniture that won’t be exposed to extremes, such as bookcases, end tables, and desks.
Oil-based polyurethane is more durable than water-based polyurethane, particularly when it comes to handling heat. Use it for furniture that will be exposed to a significant amount of wear and tear and heat extremes, such as a kitchen table.
Minwax water-based oil-modified polyurethane is suitable for both water-based and oil-based finishes. It combines the extreme durability and warm tone of oil-based poly with the easy cleanup of a water-based poly.
As if all that isn’t already clear as mud, there’s also the choice between wipe-on or brush-on polyurethane. Head over to read more about the difference between wipe-on or brush-on polyurethane and the pros and cons of each.
There are a few different types of varnish, depending on the amount and type of oil and resin in it. Spar varnish is a typical long-oil varnish and contains a high percentage of oil. It is best used for marine or exterior projects, such as exterior trim, decks, wood boats, or beach chairs. Most interior finishes are medium-oil varnishes that contain a slightly lower percentage of oil. They dry faster than long-oil varnish, produce a harder film, and are commonly used for floors. Short-oil varnishes produce a hard film that can be rubbed to a satin or gloss finish, but require extremely high temperatures to dry. They are most often used in industrial applications.
Shellac is non-toxic, dries very quickly, and is available in orange (amber) or clear. Typically, due to the wax in shellac, it does not resist heat or moisture very well. However, you can buy de-waxed shellac to use as a seal coat. Nonetheless, use it on items that won’t see too much exposure to heat or moisture.
Lacquer dries quickly, rubs out well, and is reasonably durable. Depending on the project, there are several types of lacquer. The most common is Nitrocellulose lacquer, which provides decent protection against water but is sensitive to heat and certain chemicals. It also yellows over time and, therefore, is not a good choice as a finish for light colors. Acrylic lacquer is another common lacquer and is a good choice for light colors. It has the same durability as nitrocellulose but will not yellow over time. Use lacquer for an extreme gloss finish on ultramodern furniture.
Finishing wax is not generally used as a complete finish in and of itself but can add luster and some scratch protection over other finishes, such as shellac or lacquer. If you choose to use it by itself, it is recommended for furniture, antiques, woodwork, cabinets, doors, paneling and accessories that do not need a hard protective coat.
When it comes to durability and application, there are some significant differences between the various wood finishes. This guide is a good place to start, but a lot of the choice comes down to personal preference. Ultimately, the best way to decide on a finish is to test out some of the options on sample wood and experiment a little until you find what you like.
Let me know if you have any other questions or comments, and I’ll get back to you as soon as possible.