All of our finish labels and application instructions emphasize the necessity for back-brushing during the application process. What exactly is “back-brushing” and why is it so important? Back-brushing is the term we use to describe the process of working the finish into the wood and obtaining an intact, uniform film over the entire surface. The term back-brushing is typically used when referring to applying stain with an airless sprayer; however, back-brushing is just as important if the product is manually applied with a brush.
Although the directions for use for most log home stains call for a liberal first coat or flood coat, LIFELINE finishes are designed to go on in thin coats, including the first coat. If applied too thickly, the long-term performance of LIFELINE finishes can be diminished. In other words, more is not necessarily better when it comes to applying a LIFELINE finish to your log home.
Back-Brushing Application Process
The first step in the process is to obtain a high-quality brush. A cheap three-dollar brush from Walmart will not give you satisfactory results. You need a good quality brush like a Purdy or Wooster. For back-brushing logs use a fairly wide brush, preferably three to four inches wide. Using a narrow brush takes longer and may result in visible brush marks. If you plan to hand apply the finish with a brush and pail, you will use the same brush for both the application and the back-brushing. The objective is to carry the finish to the surface with the brush and then to spread the finish out as far as it will go making sure to work it into all cracks and crevices as well as uniformly distribute it over the area you are coating. This entails some vigorous back-brushing over the area that has had finish applied to it. LIFELINE finishes dry fairly quickly, so it’s important to back-brush as you go along and not wait more than a couple of minutes before you back-brush it out.
We have formulated our LIFELINE finishes to be most easily applied using airless spray equipment. There are two methods typically used to apply finishes with an airless sprayer. The first is to step back from a wall and use the sprayer to cover a fairly large area. This works well for a contractor with a crew since a large wall can be coated in a fairly short period of time. This method requires at least two people, one spraying and at least one person back-brushing.
When using this technique back-brushing becomes doubly important since the sprayer puts out lots of small droplets and when these droplets hit the wall they result in small dots of finish, not a uniform film. It takes back-brushing to convert these dots into an intact film as well as to work the product into any cracks and fissures that are present on the surface.
The other method is to use the airless sprayer to carry the finish to the wall where it can then be brushed out. The trick is to work on small areas at a time. Although it takes longer than spraying large areas at a time, a single person can use this technique to finish their entire home. The objective is to apply some finish to a one-to-two-foot section of one or two courses of logs and then brush out what you have applied as far as it will go. You don’t want to apply too much finish and you have got to be quick with the back-brushing to avoid any stain from running down the wall. Just remember – A THIN EVEN COAT is the key.