If you have a lot of confidence in wood as most of us do, you will likely have a lot of woodwork in your home. To get the best out of wood, you have to apply a wood finish to it as a final touch. If you use a wood finish, your wood takes on a rich hue, and the grain features are highlighted.
In addition to the enhanced looks, a wood finish makes wood more durable. It protects it from spills, scratches, and daily wear and tear. However, you need to choose the right finish for the type of wood surface you need. There are three broad categories of wood finishes – varnish, lacquer, and polyurethane. In this post, we discuss in detail the features of varnish and lacquer.
Varnish vs. Lacquer
Varnish and lacquer are two very similar substances, and it is common to confuse the two. They both serve the purpose of coating wood to enhance its looks and protect it. But each one has a specific purpose. We study each of these wood finishes and clarify the difference between them and discuss how to use them best.
What is Varnish?
Varnish is a hard, transparent topcoat that we use to coat wood. Once applied, varnish protects the surface of the wood and imparts a glossy finish. It protects the wood well because of the high content of solids that it contains. An additional advantage of varnish is that it offers ultraviolet (UV) protection.
Varnish Pros and Cons
This wood finish is not without drawbacks, and here are some of the pros and cons of varnish:
- Varnish provides adequate protection to furniture from the harmful effects of the UV rays of the sun.
- You can apply varnish easily with a bristle brush.
- Varnish imparts a glossy appearance to wood.
- It also provides a fair degree of resistance to water, spills, and scratches.
- It is an affordable variety of wood finish.
- Varnish attracts static dust easily, so you need to apply it in a dust-free environment.
- It emits volatile organic compounds (VOCs).
- Varnish takes a long time to dry due to the high oil content.
- Varnish easily peels and forms cracks or bubbles if not applied properly.
- You need to apply multiple coats of varnish to achieve the desired result.
Types of Varnish
Traditional varnish is oil-based and contains natural resins. We use mineral spirits or turpentine to dilute it. Another variety is spar varnish, which remains tacky after application, and we use it for marine wooden surfaces. We do not use spar varnish on furniture.
You can also get a variety of synthetic varnishes that contain synthetic resins, and we have to use special thinners with them. One of the best synthetic varnish types is polyurethane, which we discuss in detail in another interesting post. Polyurethane does not become yellow with age. Other forms of synthetic varnish include phenolics used in marine areas and alkyds, which we get in different colors.
Water-based varnishes form yet another group which are low on toxicity and easy to maintain. This type of varnish dries quickly, within 15 to 30 minutes, and does not crack or form bubbles. It also exhibits a fair degree of resistance to water and volatile substances. Water-based varnish does not become yellow with age but tends to become cloudy with multiple applications on certain woods.
While choosing varnish, select a quick-drying one, which will take care of dust issues. It would be best to use spray varnish when you cannot use a brush easily like wicker or rattan.
Special Requirements of Varnish
You can combine natural varnish with stains and fillers. In natural varnish, shellac is the component responsible for sealing (please see our post on shellac). Alternatively, make a 1:1 mixture of equal parts of varnish with turpentine or mineral spirits for effective sealing.
Never mix different brands of varnish. Polyurethane varnish does not combine well with other fillers and stains. You can get information on mixing additional finishing material from the manufacturer’s instructions. Always follow the directions for best results.
You can use water-based varnish over stain and filler if you allow consecutive coats to get adequately dried and cured. Varnish may take to a month to cure completely but you can hasten the process by applying a shellac coat between layers. Due to the long curing time, you need a lot of patience. Also, there is a bit of a learning curve to be able to apply varnish properly.
How to Apply Varnish
Use a new, natural-bristle paintbrush to apply varnish. Avoid re-using varnish to prevent lumping. Sand down bare wood thoroughly before applying it. Lightly sand the surface of wood between layers and wipe clean it with a dry cloth.
You will find it easier to apply varnish to horizontal surfaces. Start on one surface at a time and save the large surfaces for last. Use long, smooth strokes in the direction of the grain of the wood. It would help if you left a trail of evenly-coated varnish behind your brush. In case the brush starts pulling, or the varnish begins to “miss” you can add a few drops of thinner to it. Add thinner slowly, stirring the mixture gently to prevent bubbles from forming. In case you observe any dust or lint, you can use a rosin lint picker to remove it.
To touch up small holes and dents, tip the brush once, but repeated tipping will cause blemishes. On carved surfaces, brush lengthwise, ending up on the flat surfaces using the brush tip. Run a few quick and smooth strokes with a dry brush to finish.
What is Lacquer?
Lacquer is also a finish that is quick-drying and solvent-based that we apply to wooden surfaces. It imparts a high gloss to the surface of the wood due to the shellac that it contains. Lacquer is a mixture of shellac and alcohol and may contain some other synthetic substances as well. When we apply it to wood, the alcohol dries, leaving a shiny finish to the surface. Shellac exhibits some level of resistance to damage but may discolor and become scratched in time.
Lacquer Pros and Cons
Like varnish, lacquer has certain advantages and drawbacks. Here are some of its major pros and cons:
- Lacquer dries relatively quickly.
- It forms a tough coating on the surface of wood, which creates resistance to water and chemicals.
- Often, only a single coat of lacquer is required for it to be effective.
- We get a variety of sheens in lacquer, such as high-gloss and ultra-matte.
- Lacquer tends to become yellowed in time.
- Floors coated with lacquer scratch easily.
- Lacquer does not suit all wood surfaces. You may not get optimum results if you apply lacquer to a previously finished surface.
- A significant drawback of lacquer is that they emit VOCs.
- Lacquer is a highly inflammable substance.
Special Requirements of Lacquer
We can apply lacquer to most woods except oily ones like mahogany and rosewoods as the oil tends to bleed through the finish. You can apply lacquer over a lacquer-base and many types of fillers. Furthermore, avoid coating it on oil-based fillers or stains as the lacquer solvents dissolve such existing finishes and fillers. Before applying a lacquer finish, you should use a thinned lacquer or shellac coating or any lacquer-based sanding sealer for the best results.
How to Apply Lacquer
Lacquer dries the fastest out of all wooden furniture. Even though it is thin, lacquer is more durable than shellac. You need to apply many coats for the best results. We get it in different finishes like clear, satin, matte, and several different colors.
This finish dries so fast that dust is less of an issue. But it can be challenging to work with lacquer because of its quick-dry properties. If you are a newbie, it is better to avoid using a brush for applying lacquer. Use a motorized spray gun to apply most lacquers. A word of caution – lacquer fumes are toxic and explosive, so adequate precautions need to be in place.
Lacquer Spray Cans
A viable but expensive option uses lacquer aerosol cans, which is a suitable choice for touchups and small jobs.
You need to first sand and seal the surface. Before you apply the lacquer, wipe the wood’s surface with a tack cloth to remove lint, dust, and other debris. Ensure that your lacquer is an aerosol spray can. Cover the surrounding area with newspapers and drop cloths and make ample provision for ventilation.
Hold the spray can upright above the surface of the wood. The ideal distance is about 18 inches. Any further away can cause the lacquer to “orange peel,” which is an orange skin-like pattern. If you hold your can too close, then runs and sags may occur due to excess lacquer application.
Move the nozzle in a steady back and forth action, starting at the edges and then moving over the surface in horizontal stripes. Ensure to provide a slight overlap between the spray patterns that you make on the wood. Do not try to correct any inconsistencies with a brush. You can carry out any rectifications by spraying successive layers. Always spray on lacquer thinly and add on as many layers as required.
Drying and Recoating Lacquer
The lacquer will dry in about half an hour max, but you need to allow the layer to cure completely before applying the next coat. It is best to wait for up to 48 hours or as per the manufacturer’s directions.
Once the layer is cured, you can rub the surface with 000 steel wool or fine grain sandpaper, with a tack cloth, and recoat the wood with the next layer. Repeat until you achieve the desired result.
When you have applied the final coat, leave the wood for 48 hours for the lacquer to cure. Then, lightly buff the lacquered surface with 0000 steel wool, and rub it with a tack cloth. Apply the final touches by buffing the surface to a fine gloss.
Varnish and lacquer are two very critical finishes that we use in woodworking projects. You have to know how these two types of wood finishes differ and how to use them.
Each one its plus and minus points, and you need to know about them to get the best out of each type of finish. Now, you should know where to use varnish and lacquer to apply the best possible finishes to wood surfaces in your woodworking projects.
Featured Image: James Vreeland