How to Get a Flawless Lacquer Finish
People starting out with wood finishing might find lacquer to be hard to work with. When applied correctly, lacquer creates a beautiful finish on a wood surface. You can have a nice glossy finish or one that has a rich matte appearance. Lacquer also protects wood from getting damaged from elements because it is a durable coating. A lacquer finish can be further polished to improve its appearance.
Learning how to apply this finish properly might seem complicated, but it is really not terribly difficult. There is no need to avoid it fearing that you cannot do a good job. With some practise and a bit of patience, you can develop the technique to apply a lovely lacquer finish to any unfinished wood project.
You can apply lacquer to most wood surfaces. The only two exceptions are rosewood and mahogany. These two types of wood species have natural oils that will seep through the lacquer finish, so lacquer should not be used on them. You can apply lacquer on top of another base of lacquer, on stains that don’t raise the wood grain, and on top of fillers that are lacquer-based. It cannot be applied over other types of finishes or fillers and over stains that are oil-based. The reason is that lacquer contains solvents, and these solvents will dissolve any fillers, old stains, and finishes that are not compatible with it. For sealing a surface under a lacquer finish, you can use a thin layer of lacquer, shellac, or a sanding sealer that is lacquer-based.
Always Wear A Mask During Application
Lacquer is a highly toxic substance compared to other types of finishes in the workshops. However, even the finishes that are supposedly eco-friendly will have all kinds of safety notes on the labels. The safety warnings that you read are based on being exposed to the substance during a regular work day. Unprotected exposure might put your health at risk, affecting your liver, brain function, neural system, etc. Therefore, there is no reason to put yourself at risk by not wearing a mask.
Before you spray on lacquer, always put on a mask first. The mask should block gases and vapours. If you can smell fumes through your mask, it is time to replace the filter. Masks do wear out over time. Therefore, keep track of the number of times you use your mask by sticking a piece of tape to the mask and making a mark on it every time you use it. Always keep fresh filters on hand before you tackle a big project so when you have to replace the filter, you can do so right away without delaying your project. Or, make a habit of replacing your filter after a certain number of uses, even before you detect any fumes through your mask.
Keep in mind that the active filter ingredient in your mask cartridge is charcoal. Charcoal absorbs impurities in the environment, not just when you are wearing the mask. So, in order to extend the life of the charcoal filter, you should store it in a plastic bag that you can reseal.
Should You Seal The Wood?
A wood sealer seals the pores in the wood and also raises the wood grain. With zinc stearates, it can make the sanding a bit easier. However, one drawback is that sealers have a softer texture than lacquer. If you apply too many coats of sealer, it can affect how long your lacquer coat will last. If using a waterborne, do not use a sealer. The stearates can weaken the lacquer finish’s adherence to the surface.
A lot of woodworking professionals prefer to apply a thin coat of lacquer rather than a sanding sealer. This is a good alternative in some cases, but in other cases, a sanding sealer works better. For instance, when working on a lathe, applying a generous coat of a sealer can be done quicker than applying thin coats of lacquer while the project is spinning. Also, if the project is big, spraying on a sealer is much faster than brushing on lacquer. Another advantage of using a spray-on sealer is that it can cover the nooks and corners evenly, whereas when applying lacquer with a brush, the lacquer can accumulate in these nooks and corners. The spray-on sealer dries quickly. After several minutes of sanding, the surface is sealed and smoothed out, and is ready for the top coat of lacquer.
Applying the First Coat of Lacquer
If using lacquer from a spray can, spray it on a test surface first, like a piece of cardboard or newspaper. Observe what the spray pattern looks like. This will give you some ideas on how you will control the spray when you are spraying the surface of your wood project.
When you are ready to start, hold the spray can upright, around 46 centimetres away from the wood surface. Spray slowly, with even strokes. This distance is ideal. If you hold the can farther than this, the lacquer finish might develop dimples, giving it a look like the surface of an orange peel. If you hold the can closer than this, you risk applying too much onto the surface, and the lacquer will run and sag along the surface.
Clean the Surface and Repeat
After you apply the first coat of lacquer and it is dried, you can sand out the imperfections and use tack cloth to remove residuals. This will smooth out the surface before you apply the second coat. Repeat this process several times, allowing the latest coat to dry, sanding and cleaning it, then applying another. Do this until you achieve the colour in the lacquer finish that you desire. The darker you want it, the more coats you need to apply.
The finishing process can be easier when you use pumice stone or steel wool. These can remove big imperfections that were not able to be removed by sandpaper. They can also help in creating a sheen to the finish. After this step, use paint thinner to wipe down the lacquer finish. This will get rid of any excess oils. The thinner can be used to clean your brushes, too.
Start by spraying the top edge of your project. Then, spray the rest of the surface by going from side to side, then top to bottom. Slightly overlap the sprayed strips each time, and keep a slow and even stroke.
The edges of your work will tend to have less lacquer while the middle areas have more. When you overlap the spray, you even out the coating of the lacquer. Never try to even out the lacquer film by brushing it. Apply a thin coat first, allow it to dry, smooth it out and clean it, then apply another thin layer. Repeat until you are satisfied with the finished look.