I just finished powerwashing the concrete patio in my backyard and after it dried I noticed some swirl marks which I guess were from where I pointed the nozzle. I was careful not to use it too close and I used a fairly wide spray. But there was no damage to the concrete, everything looks and feels flat with my hand. Do these marks eventually dissipate? Are these marks characteristic of using a powerwasher?
your swirl marks just indicated areas that are cleaner than the rest
They will even out in time. They are just spots that did not get as clean as others. You can go back over it, a little slower this time, and reduce or eliminate it. I find it tends to become a lot less noticeable in a day or two.
If you clean large flat surfaces often, then you should consider purchasing a powerwasher attachment designed for such applications. Otherwise, you need more practice in using the typical wand that comes with a powerwasher. Swirl marks indicate that you aren't making good lateral passes.
When using the wand, I powerwash the same way that I would use a power painter to paint a large flat surface. The wand is ALWAYS perpendicular to the surface and the wand moves at a uniform rate across the work. Modest overlay is maintained on each pass. The wand is ALWAYS at exactly the same distance from the work. Etc.
That is a slow process and difficult for some to master. So two other options are possible. First is a larger power washer which enables a larger area to be cleaned on each pass. Better yet is a "hover-craft" style surface cleaning attachment which provides an extremely uniform surface cleaning. Karcher makes one for $50 called the "T-Racer Wide Area Surface Cleaner", and 2.640-508.0 is the part number.
Check out this site:
This unit has two different sets of jets, based upon the power range of your power washer. Also, the very easy to use jet height adjustment makes it possible to power wash concrete as well as washing wood flooring without damaging it. My teenage son learned to use this attachment properly in just minutes and has made quite a bit of money cleaning concrete, decks, siding and other flat surfaces for neighbors.
Good luck, Gideon
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