Lacquer is typically thought of as the best all-around finish for wood. Why? Well, It dries quickly, and it’s durable. There are several different types of lacquer available to finishers. Understanding the various characteristics of each will help you choose the right one.

Nitrocellulose Lacquer

Nitrocellulose lacquer is what I consider basic lacquer in it's simplest form. This is the type of lacquer you will find on most household furniture. It is made by mixing fast-drying solvents with wood and cotton pulp containing cellulose that has been broken down by nitric and sulfuric acid. It was first invented around the year in 1921.  Not long afterward, nitrocellulose lacquer replaced shellac and oil-based varnishes and became the industry standard for furniture and cabinet manufacturers.

The benefits for large and small shops are: nitrocellulose lacquer is relatively inexpensive and dries quickly. The cured resins provide a fairly good protective layer of film over the wood. Once dry, it rubs out really well; and its slightly amber color enhances both light and dark woods with a warm tone. Also, because it is an evaporative finish, each new coat of lacquer will blend into all the previous coats that are applied before the finish is fully cured. Lacquers are very thin finishes containing little in the way of solids. They are dry when the thinners evaporate. Unlike some reactive finishes, they do not go through a secondary oxidation curing. Curing time for nitrocellulose lacquer can take upwards of a month.

The disadvantages to using nitrocellulose lacquer are: The film can yellow as it ages, and it can also shrink, causing cracks (often called crazing) to form in the surface. Although some lacquers are made and sold as brushing lacquers (Deft, for example), you can achieve much better results by spray finishing, keeping in mind that the overspray is highly flammable. Buildup of overspray on any electrical component, and the airborne vapors are highly flammable and can ignite with a spark, causing a fire or explosion.

Because Nitrocellulose lacquer dries quickly, when applied under conditions of high humidity, the lacquer film can trap moisture and cause the finish film to appear cloudy -- a problem we call blushing. You can overcome blushing by adding a slower-drying thinner, called lacquer retarder, which allows the moisture to escape before it gets trapped in the film. You can also use a product called "No Blush", to eliminate the blushing. No Blush can be purchased and is a must if you finish with Nitrocellulose lacquer.

An important note on Blush, is that it MUST be removed by using a retarder thinner before another coat of lacquer is applied. If not, the haze will be locked in and you will not be able to remove it.  You can also make your own "no- Blush" using half lacquer retarder thinner and half lacquer thinner for application using a spray gun.

Acrylic lacquer

When working with unstained, light-colored woods (such as ash, birch, and maple), finishers and furniture makers need to avoid the yellowing problems associated with nitrocellulose lacquer as it ages. The finishing industry responded by developing lacquers containing acrylic resins that are truly “water-clear.” Acrylic resins go on crystal-clear and stay that way over time. The most widely used of these products is called CAB-acrylic lacquer, made with cellulose acetate butyrate and acrylic resins.

CAB-acrylic lacquer dries to a less brittle and more flexible film than nitrocellulose lacquer.  Other than that you will find the working properties are much the same. Acrylic lacquer is best applied by spray equipment, diluted with regular lacquer thinner to obtain the ideal spraying viscosity, and it is fast-drying. CAB-acrylic lacquer is often used as a protective topcoat over colored pigment lacquers to make them wear better and to enhance their resistance to scratches.

Catalyzed lacquer

Catalyzed lacquers are hybrid reactive finishes that cure chemically, not solely through the evaporation of solvents. Catalyzed lacquers contain some nitrocellulose resins, but the addition of urea resins makes these products much more durable. The chemical cure is initiated when an acid catalyst is added to the mixture. Cat lacquers have overtaken Nitrocellulose in the refinishing industry as the standard finish choice. This is partly due to it's increased durability, thicker film due to higher solids (requiring less coats),  faster cure time and higher tolerance to humidity.

With catalyzed lacquer, you are faced with the choice between either pre- or the post-catalyzed versions. Both of them have a limited pot life, based on when the catalyst is added. The manufacturers of pre-catalyzed lacquer add the catalyst either at the factory, or in the store at the point of purchase. We use Sherwin Williams at The Restoration Studio and I have them add the catalyst at the store. If you buy a post-catalyzed lacquer, you will have to purchase the catalyst separately, in another container, and do the mixing yourself. When mixing your own, you have to be precise to end up with a finish that will cure properly.

Pre-catalyzed lacquers are most common because they use a less aggressive catalyst, giving it a longer pot life. Post-cat lacquers cure faster, often achieving a hard cure in only 24 hours. Pre- cat can be a little slower to full cure, but eventually both achieve similar durability and hardness.

Happy Finishing!!