Those wavy light-and-dark bands on your concrete are wand marks — the permanent record of a pressure washer used without a surface cleaner. They are the single most visible difference between DIY work and professional concrete cleaning, and once they are there, they are there.
How the stripes happen
A pressure wand cleans a narrow arc, intensely. Sweep it across a slab and every stroke overlaps the last one unevenly — different distances, different speeds, different dwell. Concrete records each difference as a tone change.
You cannot see the stripes while working, because the whole slab is wet and dark. They appear as the concrete dries, by which point the job is done and the pattern is baked in.
What a surface cleaner does differently
A surface cleaner is a shrouded deck — it looks like a lawnmower — with pressurised jets on a rotating bar underneath, held at a fixed height. Every square inch of the slab receives identical pressure, distance and dwell, so the finish is uniform edge to edge.
It is also several times faster than a wand, which is why professionals use one for every flat surface: better result, less time. The wand still has a role — edges, corners, vertical faces — but never as the primary tool on open concrete.
Can stripes be fixed?
Only by re-cleaning the entire slab uniformly with a surface cleaner, which levels the tone differences by bringing the whole surface to the same state. Deeply etched wand marks — where the tip was held too close and cut the surface — are permanent.
If you are hiring the work out, one question settles it: ask what they use on flat concrete. The answer should name a surface cleaner without hesitation.
Striped driveway? We can usually level it. Send a photo and we will tell you. Read more about professional concrete cleaning →