By Bentler Painting (Vince Bentler) and Kelly Hopkins
Most painting contractors in the Scranton/Wilkes-Barre areas use pressure-washing as their magic bullet to cleaning wood houses before painting. The loose and peeling paint will be lifted up and blow off right off the wood siding and trim from the "power" of the water. Painting contractors often see it as a way to save time during a project and avoid the labor-intensive task of hand-scraping loose paint off a house board-by-board.
However, to achieve a long-lasing paint finish, the cleaning phase during the preparation process of wood houses must be approached differently than it would for other types of siding such as aluminum, vinyl, and masonry.
Why? Moisture is wood's worst enemy. Pressure-washing forces incredibly high levels of water into the wood's pores. Even a pressure-washer set on a low setting is strong enough to push moisture into the existing film(s) of paint, into the wood pores, and reach underneath the backside of the wood siding itself which is a cause for concern with mold formation. Several weeks of dry time is often still not enough time for the wood to become fully dry. Although the surface of the wood may feel dry to the touch, moisture still lays in the deeper levels of the wood.
So, what happens to the new (and existing) layers of paint after the house is power-washed? As the home's wood siding heats up each day from being hit with the sun's rays, the lodged-in moisture will try to escape, and it will do so by lifting areas of the paint off in bubbles. The appearance of peeling paint won't happen instantly on the freshly-painted home; but, very noticeable areas of peeling paint will be seen after only 2 years.
Well then, how should a painting contractor clean a wood house before painting? The proper method of cleaning wood siding and trim is to apply a house cleaner, tsp, or bleach/water with a spray nozzle hose and scrub the siding by hand with a siding cleaner brush. Next, rinse off the cleansing solution with a the gentle spray of a simple garden hose. The wood siding and trim will be ready for the next stages of the painting preparations within a few days of dry time.
If you are a wood house homeowner in the Scranton/Wilkes-Barre areas and would like your new paint job to last a long time, it is highly advisable to choose a contractor who does not use a pressure-washer to clean the wood surfaces before painting. Yes, this may seem very hard to believe since pressure-washing has become extremely "trendy" around here the past decade or so.
Most home builders and carpenters would "cringe" at the thought of a painting contractor applying water from a pressure-washer to wood house, and so should you.
Bentler Painting specializes in wood house painting; if you have any questions for us, feel free to contact us via our Google+ page or our website, and we would be happy to help you out.