When applying lacquer to wood, the number of coats required varies based on the wood type, application method, and the working environment.
Typically, you should anticipate applying at least 3 to 5 coats for brush applications and 6 to 9 coats if using a spray gun.
Water-based lacquer, in particular, penetrates the wood and dries to a hard, durable finish, providing waterproof protection and excellent heat resistance.
What is Lacquer?
Lacquer is a popular wood finish today, and you will often find it on high-end furniture, dining room tables and chairs, and such. It is a fast-drying finish, dries to a clear and transparent appearance as it ages, and is impervious to water. The last two of those characteristics are why it is as popular as it is – it does not yellow as it ages and is good protection against spills. It also requires little to no maintenance.
It is most often made with a mixture of nitrocellulose and solvents to make anything from a gloss to a matte finish and everything in between. Nitrocellulose is cellulose nitrate and is made from wood pulp and sap from the lacquer tree, to which is added resins to keep it from becoming too brittle.
It is sometimes confused with shellac, which is an excellent wood finish. However, lacquer is more durable and will last longer on your wood.
Types of Lacquer
Nitrocellulose
In fact, there are 5 types of lacquer, of which nitrocellulose is only one. Nitrocellulose was used by automobile manufacturers back in the 1950s as a metal finish. It has been and continues to be the first choice as a finish for high-end musical instruments.
It dries to a high-gloss finish and is easier to work with after curing than other types of lacquers. It will develop a reddish-amber color over time and gives a rich luster and patina to some woods. However, because of the color developed over time, it is not a good choice of finish for lighter woods like maple and ash.
Acrylic lacquer
This lacquer was developed in the 1950s for those lighter woods like maple and ash. It contains synthetic acrylic polymers and dries to a water-white color that resists coloring with age.
Water-Based Lacquer
This type of lacquer contains fewer hazardous chemicals, is less toxic, has no odor, and tends to be more durable than the other types of lacquers. They also dry faster (they are water-based) and are more environmentally friendly. They also tend to last longer and are cheaper than acrylic lacquers.
Common Uses of Lacquer Today
In addition to high-end furniture and high-end musical instruments, lacquers are also used for general wood finishing, nail polish, sealing metalworks, and in Eastern lacquerware. We have a lovely piece of Chinese furniture in black lacquer in the dining room, and you’ve likely seen Asian furniture with lacquer finishes.
It is more common today, though, to find that those who use lacquer as a finish for their woodworking projects favor a water-based lacquer. This is to avoid the most common solvents used in manufacturing lacquer, including toluene, formaldehyde, and methanol.
When using a lacquer with solvents like these, a respirator is highly recommended, and the room where it is being applied should be well-ventilated with good air circulation. Once the lacquer has dried and cured, though, there are no noxious odors or harmful chemicals lingering in the air.
The water-based lacquers are more environmentally friendly, are much less toxic, and don’t present any noxious odor when being applied. Damage to the finish is easily repaired, also with a reapplication. It is designed to be resistant to chipping and provides a waterproof seal to the wood.
Difference Between Lacquer and Polyurethane
Separate and apart from the chemical composition of the two, the lacquer will penetrate the wood when applied, whereas polyurethane is merely a film finish. While both finishes dry hard and are durable, polyurethane forms a plastic shell around the wood to provide protection; lacquer, on the other hand, becomes a part of the wood when it penetrates and also dries to a hard finish that provides protection to the wood.
Lacquer is also thinner than polyurethane and is better applied by a high-volume, low-pressure spray gun. We’ve written in the past about HVLP spray guns, and if you aren’t familiar with them, you can check out that previous article.
Polyurethane is also less resistant to heat damage from a hot cup of coffee, for instance, or something right out of the oven. Of course, this should never be done to any tabletop, but you get the point. Lacquer, on the other hand, offers better protection against damage from heat.
A clear lacquer has been shown to be able to tolerate as much as 900 degrees Celcius intermittently and a continuous heat of 800 degrees Celcius. Polyurethane will melt under that much heat.
Lacquer Application on Woodworking Projects
How many lacquer coats should you plan on for your woodworking project? It depends. The type of wood will have an influence on the number of lacquer coats to apply, as will the manner of application between brush and spray gun. The environment in which it is being applied will also affect the number of lacquer coats.
The type of wood you are finishing will affect the number of coats, as softer and more porous woods will absorb more lacquer. While absorption is good, it is the thickness of the coat that will also offer greater protection to the wood. The environment comes into play as a more humid space will slow down the evaporation of the water in the lacquer, as you might guess.
Generally, most painters and woodworkers will tell you that 3 – 5 lacquer coats are the rule to follow when the lacquer is being applied by brush. Brush application will result in thicker coats each time, and that number of coats will give a good thickness to the coating, and the wood will be adequately protected.
However, spray application results in a thinner coat each time the wood is sprayed. To achieve the same degree of thickness on the wood’s surface with thinner coats, you will want more coats, of course, and 6 – 9 lacquer coats are what most painters and woodworkers will tell you to plan for on your project.
As far as the preparation of the workpiece, a smooth surface will result in a smooth finish. This is basic woodworking. Fine-grit sandpaper will get you that smooth surface, and a sprayed application of 6 – 9 lacquer coats should offer plenty of protection to the wood.
Like polyurethane use, a very light and careful sanding with high-grit paper between lacquer coats will give you a smooth finish, although this is not entirely necessary. Like polyurethane, also, you must wait until one coat has dried before adding the next. Water-based lacquer will dry to the touch in as little as 30 minutes, and in 2 hours, another coat can be applied. This means 2, if not 3, coats can be applied in an afternoon.
Video Demo of Lacquer Application
Since we mentioned both lacquer and an HVLP spray gun, we thought a video demo on lacquer application by spray gun would be helpful and informative. It covers a number of points we’ve mentioned in this article.
We like lacquer at Obsessed Woodworking and recommend you give it a try if you’ve not used it before. Follow both the recommendations on the container label as well as the PDS (product description sheet) offered on the brand’s website (most have them published and are easy to find). Lacquer will give your project great protection that will last for years with only minor upkeep.