There are many choices for just the right finish for your woodworking project. Recently we’ve spent a lot of time discussing oil finishes, particularly Rubio Monocoat, and oil finishes in general. But today, we want to consider two other wood finishes choices – lacquer and polyurethane.
What is Lacquer?
Lacquer, one of the popular wood finishes today, is a wood finish that is commonly used on high end furniture projects. It’s very fast-drying, is impervious to water, and will maintain its transparency as it ages. One of the main reasons for its popularity is that some types of lacquers do not yellow with age, although it is popular, too, because it protects well against liquid spills and requires little to no maintenance.
It’s typically made with a solution of nutrocellulose and solvents to make either a glossy or matte finish. Nutrocellulose (cellulose nitrate) is made from wood pulp, to which resins are added to make it less brittle when composing lacquer. The solvent is lacquer thinner. While lacquer and shellac are both popular wood finishes, lacquer is more durable and longer lasting.
Nutrocellulose was used by car manufacturers as a car finish through the late 1950s. At about that same time, furniture and musical instrument makers also switched to nutrocellulose lacquer, eventually just calling it lacquer.
Nutrocellulose is used in many products today, including smokeless gunpowder, inks, varnishes, lacquer coatings, and even ping-pong balls. There are actually 5 types of lacquer, of which nutrocellulose lacquer is only one. Here are the three most common lacquer types:
Nutrocellulose lacquer. As mentioned above, this type of lacquer has been the go-to finish for high-end musical instruments. It was also the primary choice for automobile manufacturers in the 1950s for metal finishes. It dries to a high-gloss finish and is more malleable after curing than a traditional lacquer. This type of lacquer will adopt a reddish-amber color as it ages, offering a rich luster and patina to some woods. It is not a good choice for lighter woods like maple and ash because of that coloring with age.
Acrylic lacquer. Developed in the 1950s for use on lighter woods like maple and ash, this type of lacquer contains synthetic acrylic polymers and dries to a “water-white” that resists yellowing with age, allowing woodworkers to avoid those yellowing (coloring) problems associated with the use of nutrocellular lacquer.
Water-based Lacquer. These lacquers are very different in composition and contain fewer hazardous chemicals. They are less toxic, have no odor, and tend to be more durable than other types of lacquers. They also dry faster, are more environmentally friendly, last longer, and are less expensive than acrylic lacquers.
What Are The Most Common Uses of Lacquers?
We’ve already mentioned the use of lacquers by musical instrument craftsmen. Additionally, lacquers are used:
- As a wood finish
- As a nail polish
- As a metal sealant and protector (automotive industry, as an example)
- In Eastern lacquerware
Those who use lacquer today tend to lean toward the use of water-based lacquer. Among the most common solvents used in the making of other types of lacquer are toluene, formaldehyde, and methanol. Concern about using lacquers with these solvents makes water-based lacquers a frequent choice as a wood finish, along with oil finishes like linseed and tung.
Water-based are more eco-friendly, do not carry the odor of other types that require some safety measures when being used, and are much less toxic. It’s a popular and durable finish that dries to a glossy shine.
The occasional damage to a lacquered finish is easily repaired. Lacquer is a thin coating and blends well with previous coats. This distinguishes it from polyurethane which often requires sanding to enhance its adherence to previous coats as the finish is built up.
What is Polyurethane?
Also a popular wood finish today, polyurethane is basically a plastic in liquid form that creates a hard, plastic film over the surface of the workpiece. It is much thicker than lacquer and not as easy to apply unless it is thinned. It comes in both water-based and oil-based versions, and although they differ in their dry times and compositions, they are both a durable and protective coat on your woodworking projects.
Less toxic than oil-based, this polyurethane is also odorless. It does not yellow over time and dries faster than the oil-based sibling. However, it does not stand up well to high heat, and without protective measures, is not a good choice for any surfaces that will face heat unless protective measures are taken.
Durable but slower drying, this polyurethane can withstand exposure to high heat. But, unlike water-based polyurethane, it is toxic, and precautions need to be taken when applying it, especially doing so in a well-ventilated environment. Unlike lacquer finishes, it does not penetrate wood; it merely forms a solid, plastic film coat on the wood’s surface.
And, unlike water-based poly, it does tend to leave a yellowish color on lighter-colored woods. Because of its thickness, it can not be sprayed unless a thinning agent is applied, and when applied by brush, it needs a natural bristle brush for best results.
Lacquer vs Polyurethane
Now that we have determined what each of these wood finishes are let’s examine their best, or at least better, uses to distinguish them among our various projects.
Lacquer finishes penetrate the wood’s surface and form a durable finish, whereas poly does not, forming a film finish of hard plastic when dry and fully cured. A poly finish, however, is also durable.
Quality of Finish
Poly will tend to be more durable than lacquer. While lacquer, too, is durable, it is more susceptible to dings and scratches, and discoloration than poly.
Poly is thicker and, if not thinned, requires brush application. This makes it susceptible to brush marks, so extra care must be exercised in its use and application, as well as a fine brush.
Lacquer, on the other hand, is thinner and a spray application with a high-volume low-pressure sprayer. We’ve written about HVLP spray guns in the past, and you will find a past article here. These spray guns apply even coats quickly, although they are more expensive than a high-quality fine brush, running anywhere from $50 – $250 vs. under $10 for a natural bristle fine brush.
Drying and Curing Time
Lacquer can dry within about 10 minutes, much quicker than poly. Water-based poly is faster drying than oil-based, which can take up to 24 – 30 hours to dry completely. Because it dries much faster, it is easy to apply multiple coats of lacquer within the same time it takes for one coat of poly to dry fully.
Which Finish To Use On a Tabletop
Now that we have a clear picture of the two as a wood finish, it’s likely you’ve already answered the main question of the article.
Tabletops are likely to be exposed to high heat. Hot serving platters and casserole dishes, as well as the dinner plates the meals will be eaten from, and a hot cup of coffee or tea, are the most common sources of that heat.
If precautions are not taken, and a water-based poly is the tabletop’s finish, the heat will cause damage to that finish. Placemats, trivets, and coasters are essential for the protection of the tabletop.
Bookshelves, bookcases, and desks are less likely to include heat sources as a dining room table would. That water-based poly will be a better choice for those projects.
For kitchen or dining room tabletops, and if you have chosen poly as your finish, an oil-based poly is the far better choice than the water-based. It can withstand high heat without being damaged. Its use carries other concerns, like its chemical composition, toxicity, odor, and much longer drying time. But, for the protection of a tabletop that would be exposed to heat sources, it is the better choice among polyurethanes.
As for lacquer finishes, we have a higher tolerance for heat with its use. A clear lacquer has been shown to tolerate intermittent temperatures of up to 900 degrees Celsius and 800 degrees of continuous heat. This is a much higher tolerance than that of polyurethane.
This leaves us with an equivocal answer.
If you take the necessary protective precautions, a water-based polyurethane will work – – placemats, trivets, coasters, and extra care.
If you don’t want to think about being so careful and prefer a poly finish, the oil-based poly is the choice you want to make.
Or, you can choose the lacquer finish. Quicker drying time, multiple coats within the time it takes for an oil-based poly, easy repairs, a water-based lacquer is a very good choice for that kitchen or dining room table. Its higher heat tolerance without causing damage is a compelling difference to warrant its use.
This video actually puts both lacquer and poly to the test in a variety of ways and illustrates what we have discussed in this article.
After our research, our own use, and this video demonstration, we would opt for a lacquer finish for our tabletop, and specifically a water-based lacquer finish. We think you will agree.