Tips and Tricks When Power Washing
Power washing is the most common method of cleaning and preparing log and wood structures. When done correctly, it will leave you with a surface ready to be stained. So, how do you power wash to get the best results for your staining job? Here are some tips to keep in mind.
Before you start, always apply them carefully according to directions and fully neutralize them afterwards. Don't guess! Use pH strips to make sure. When not properly neutralized and removed from the surface, chemicals will interfere with proper stain adhesion and performance.
Be aware of your water needs. Power washing can often run a well dry, so if you're using well water, consider whether or not you need to bring in additional sources.
Pay attention to the items in the path of the water! On the interior, remove any paintings and wall decorations, move furniture away from the walls, and put down towels and or plastic drop cloths to catch any water that may get inside. Having an extra person inside to watch over water infiltration is a good idea. If working on a deck that is above a patio, protect anything sitting on the patio with tarps, or move it so it won't get wet.
Technique
Use a power washer with a fan wand (typically a 40 degree spray angle).
If possible, use hot water. As with any cleaning, hot water is more effective and quick than cold.
Always practice in an inconspicuous area to master the technique.
Fun fact: The distance the wand tip is positioned from the surface is the most important part of proper power washing! Power washers typically operate between 500 and 3,000 psi. The distance between the nozzle and the wood surface (anywhere from 8"-36") is more important than the pressure rating of the power washer. If the wand is located too close to the surface, excessive "felting" or "fuzzing" of the wood can occur, which then requires a great deal of secondary hand prep to create a good stainin surface. If you keep the spray wand too far away, you'll only be doing a light cleaning and will not remove all of the unsound surface wood fibers that can shorten the life of a stain. Find that distance from the surface where the water spray just begins to aggressively fuzz the wood, and then back off an inch or so. Maintain that distance throughout the job.
As with any agressive cleaning, don't stop or start in the middle of the wall or board. Spray the wood like you would when spraying paint, feathering it in and out of areas to keep a consistent look.
After power washing is complete, remove all felting that may be present with Buffy Pads, Osborn brushes, or sandpaper. Buffy Pads are the fastest and easiest system on vertical walls or small decks. Floor sanders will be most efficient on large decks.
You're not done yet! Allow the wood to thoroughly dry.
Use a moisture meter to be sure the moisture content level is between 6-19%. In very dry areas (like Las Vegas) the moisture content of the wood should be towards the low end of this range before applying coatings. In areas like Juneau, Alaska the wood will never get lower than about 16-18% moisture content. The cooler and more humid the weather, the longer it will take to dry.
Finally, vacuum or blow out standing water.
Water will collect in upper-curvature checks. If allowed to sit in there, it’ll soak in, creating localized areas of high moisture content. When that moisture tries to get out, it could cause your stain to peel. Avoid that by getting rid of the water before staining.
Published on: April 20th, 2018
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