You Need to be a Badass to Brush a Finish
Most woodworkers that I have met, try to finish their own projects, and while they may do great woodwork their finish often falls short and lets the world know that their project was not finished by a professional woodworker or finisher. The typical look of the less-than-perfect finish is one of obvious and often errant brush strokes. While I think it is possible that some of these finishing jobs are seen as perfectly acceptable by less discerning eyes, I would like to think that the applier of these lackluster finishes knows and sees that they could do better, but are at a loss for how to correct the problem.
My first solution, and always my first recommendation, is to purchase a high-quality spray gun and start spraying your finish. A spray gun is quick, capable of producing a flawless finish and may even make finishing fun. There are lots of reasons why you may not feel comfortable spraying a finish, but there are at least 492 reasons why you should spray your finish–the first 485 being that you need to be a badass to brush a good finish.
Brushing a good finish requires an amazing level of patience, attention to detail and a willingness to not cut corners. It can be done, but often the person that relegates themselves to brushing a finish is usually the same person that struggles to produce a good finish because they aren’t patient, aren’t paying close attention and are trying to do as little work as possible to call the job done. It is a crazy irony of a situation, but it happens all the time.
Now, first let me be clear, I don’t have a problem with brushing a finish. I think it is perfectly acceptable and sometimes required, but it has to be done right just to not look bad, never mind looking great. Luckily, there really are just a few tidbits to keep in mind that are the keys to a beautiful brushed finish.
Apply Thin Coats
You will be tempted, at all stages of finishing and throughout your entire life, to apply a finish that is thick and wet. Often this is under the misguided notion that thicker is better and it will speed things up, but nothing is further from the truth. A thick finish coat is the first and deadliest weapon in the unprofessional finishers arsenal. No matter how well you apply a thick coat of finish, it will somehow, somewhere on your woodworking be less than perfect and scream, “This dude doesn’t know what he is doing!”
Thick finish coats show deeper, more obvious brush strokes because they are just that, deeper. Thicker coats also tend to run and, at very least, sag. And, the last thing, that shouldn’t be underestimated, is that thicker finish coats take much longer to dry, which allows more debris to get in your finish, lengthens the dry time between coats and often leads to blemishes from handling a piece before it is dry. There is, as far as I can tell, nothing to be gained by brushing on a finish in thick coats versus thinner coats.
Applying thinner coats can and should be thought of in two ways. The first is simply the amount of finish moved from your brush to the surface. When applying the finish, put on just enough material to cover the surface and nothing more – do not leave puddles. There should be so little on the surface that it is impossible for the finish to run or sag. The second way to think about thinner coats is in the viscosity or the thickness of the material itself. Thinner material will flow fast, like water and thicker material will flow slow, like syrup. Make sure your finish is not too thick by adding the proper solvent for your finish, like water, mineral spirits, alcohol or lacquer thinner if needed. Many finishes will be fine directly out of the can, but some thicker finishes will benefit from a little thinning. Be sure to read the can for proper thinning options and test your finish on a piece of scrap material first to see how it flows and lays down.
Pay Attention to Your Brush Strokes
No matter how well you apply a finish with a brush, brush strokes will most likely be visible at some point. The good news is that wood has a grain to it that can help hide the brush strokes. The secret is to apply the finish with brush strokes that follow the grain. Don’t go all willy nilly and just slop it on. This is where the patience and attention to detail really come into play and where you have to let your inner badass shine.
Plan out your brush strokes so there aren’t any unintentional stops or starts. Where parts meet make sure to stop and start where they stop and start. On mitered corners, start with the brush at a 45 degree angle so the brush marks only follow the grain of each board.
Lastly, make sure that your brush strokes follow the full length of the work. If a single piece of wood is 30′ long, your brush strokes should be 30′ long in a single uninterrupted and reasonably straight pass. It may sound a bit overboard, but that is what it takes to do this correctly.
Keep a Wet Edge
Working with a brush is not fast. While you are messing around with the application and focusing on your brush strokes, it is possible for some finishes (especially paints) to start to dry while you are applying them, requiring you to step up your game even more. It is important to keep a wet edge while you are working, so each new brush stroke blends with the previous one. If you move too slow and the finish has dried or started to dry, you will basically be applying two coats as opposed to only one. If you are finishing woodwork, this will cause the finish to have an unevenness about it, either because of a difference in the sheen or in the way it fills the wood pores.
When working large open areas, plan out your approach and move quickly. Do what you can to quickly get the finish on the surface and then focus on your brush strokes to finalize things. A small-nap roller can even be used to help speed up delivery to the surface before final brushing. If you have a choice, work in cooler temperatures (always out of the sun) and with reduced airflow to slow down the drying.
Any finish application, whether brushed or sprayed will benefit from being horizontal. Having your pieces flat on a work surface during finishing allows you to fully see what you are doing, especially with good reflected light and helps the finish to level out while drying. The other obvious benefit is that you should get no runs on a horizontal application unless you are extremely talented. You may find it worthwhile to completely finish your piece before assembly so you can keep all of your parts horizontal.
Choose the Right Brush
There is much to be said about brushes, but for me it comes down to one simple rule. Don’t ever use a cheap brush. Don’t even let them in your shop. If you have a cheap brush in your shop (you know, the one that you were only going to use for applying glue or something else non-technical), you will inevitably end up trying to use it for some sort of real finishing and it will not turn out well. I would argue that it is better to not finish at all than to try to finish with the only brush you could find in the shop which was purchased in a 10-pack at the dollar store. Using a good brush gives you at least a fighting chance. For those of you that want a bit more technical input, remember to use natural bristles only for oil-based finishes and synthetic bristles for either water-based or oil-based finishes. It all comes down to the fact that natural bristles don’t like to be soaked in water and synthetic bristles can be soaked in anything.
There you have it. Five simple little rules, all of which if you completely follow, still only give you about a 50% chance of producing a beautiful brushed finish. The other 50% is dependent entirely on your willingness to not take anything that resembles a shortcut and on you being a badass every step of the way.