Some only compare a single application method against another – say brush and roll against the spray application. Fact is there is no comparison when it comes to getting the paint out of the bucket and on the wall. The airless spray method will always win. Yet some believe themselves to be the folklore hero “John Henry”, the man who could keep up with the machine till his last breath.
Facts are the spray method doubles the area against the roller application on almost all substrates. For instances a published contractor estimating guide rate of Board & Batten (T1-11 siding) states an average application roller rate is 175 SF/HR vs. the spray method covers twice the square footage – 350 SF/HR. Another example are exterior fixed slat louvered shutters, 5’ x 2’ Avg. (one-side) brushed will produce 4 to 6 shutters an hour; where the production to paint the same shutter is 12 an hour. Of course it all depends on the individual painter, but we are talking averages in an estimating guide.
So, if compared on a production rate alone the spray method is faster. Yet the comparison is not over with production rates alone, but in most discussions that is where it stops. As stated earlier the sprayer gets the paint out of the can faster; but is faster better? Well, the answer is “Yes” and “No”. Simply put there are two sides to a story.
The impression is paint is getting on the wall really fast and that is a good thing, but the problem is the spray application does not always seal exterior wood or siding substrates. Spray application methods use the physic’s concept of atomization to evenly apply the paint over the surface. Problem is unless the surface is completely smooth the paint will not reconnect itself once it is on the surface, thus leaving an unsealed substrate. This is the main point of the argument between which method is better.
So combing both techniques; brush, roll and spray the best results are achieved called ‘back-brushing or back-rolling. Back Brush / Roll is a method where sprayed paint, while still wet is worked into the substrate with a brush / roller to connect the paint droplets over the surface to improve uniformity and durability. This process pushes the primer or paint into the surfaces, filling small cracks or cavities if you were. Now the best of both worlds; quickly getting paint out of the can and getting a more uniform finish over rough surfaces.