Science, asked by cheertsabadric, 1 year ago

how to pressure wash deck before staining

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Answered by Anonymous
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Once you have scrubbed the entire deck you are now ready for rinsing. Again, a conventional hose and nozzle may work. But if you are going to use a pressure washer, this next section will instruct you on the correct techniques to use. NOTE: Sometimes raising woods fibers is a direct result of applying pressurized water to a wood surface. Even the most cautious technique may leave behind these raised fibers. These raised fibers can be removed rather easily. More on that later. 

Always engage the trigger away from the surface, and away from anything that it may harm including windows and people. The water that emerges from the tip is called a ‘fan.’ The tip is rated in degrees. The degree of angle indicates the fan size. Zero (0’) is typically a stream of water. You will never want to apply a stream of pressurized water to wood. A 40’ to 60’ (degree) tip size is standard for cleaning a deck. Bringing the fan to the surface you want to sweep the deck. 

Begin “Sweeping” the deck from the house side out. Be consistent in the length you tip it from the surface. This constancy will prevent lap marks. The goal in sweeping a deck with a pressure washer is to remove the dirt leaving behind no traces of the pressurized water. Too little pressure, or having the fan too far from the water will result in a ‘less’ cleaner surface. Too high pressure, or too close to the wood will result in a stripped area. In sweeping the surface you need to begin and end with the same pressure. 

“Feathering” is a technique that may help you mask the starts and stops of the sweep. With this technique you want to overlap the areas previously swept, making sure that the point where the nozzle is closest to the wood begins at the point where the sweep ended on the previous stroke. Always working with the grain or the length of the board, this technique requires more strokes and is slower but does an exceptional job. It also ensures that as much of the cleaner is removed/diluted as possible. Excess cleaner left on the deck surface can have long lasting and detrimental effects. Feather is the most efficient method for using a pressure washer on a deck surface. 

The “Long Sweep” is another method. Using this method you bring the fan to surface and walk the fan along the length of the board. The tip should be at the same distance from the deck from the beginning of the stroke through the whole length of the board. This method may require several passes. This method works fine for decks that have no railings or obstacles where starting and stopped can be problematic. If you use this method with railing structure you will leave behind a line across the surfaces where the fan stopped. These lines will be difficult to remove as more pressure will have to be applied. Thus starts a pattern of more and more pressure and risks damaging the surface. 

Corners can sometimes be a challenge for pressure washer operators. The water has no direct place to travel and often results in the face of the user. Jettison debris and chemicals can be harmful. Always wear appropriate bodily protection. When approaching a corner, engage the fan and bring it into the corner first, spraying the debris out. Try not to work yourself into a corner, always work out of a corner. In doing so you may find that you cross grain spray for a short time. This is fine as long and the distance is greater and pressure is lower on the cross grain than with the grain. The best way to remember this is the letter “L.” Long sweep into the corner, and a short sweep out of the corner with the grain. 

Once you have completed the whole deck. Put away the equipment, and allow the deck to dry. Decks look very different from wet to dry. Small imperfections can often go unnoticed when the deck is wet. Also, raised fiber will be virtually impossible to remove from a wet surface. If the topcoat (sealant or stain) you have selected is a one day application to be conducted after washing before the deck dries, it is still my recommendation that you allow the surface to dry a minimum of 24 hours. Once the deck has dried inspect your work. The finished product should leave behind no lap marks, minimal raised fibers, and clean wood. The surface should be consistent. No areas left unwashed. And no areas over washed. If you deck looks like this, pat yourself on the back, you have done a fine job.
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