Slab concrete going gray gets noticed, because the driveway is big and you stare at it twice a day. Pavers and flagstone cheat. They hold dirt in every pore and every joint, so they fade evenly, all together, and nobody notices until the day they see a clean one.
Why they gray out
The same cast as everywhere else on the property: algae and mildew where it stays shaded, packed grime in the joints, moss between stones where it stays damp. On a shaded walkway the moss can be doing more of the coloring than the stone is.
The pressure they can take, and not a pound more
This is where a rental wand does real damage. Sand joints blow out, mortar chips, and soft stone etches. These surfaces get cleaned low and patient, letting the joints and the mortar set the limit. The finish comes back even because the method is even.
What else gets this treatment
Paver patios, walkways, and driveway borders. Brick steps, stoops, and facades. Retaining wall block and stone caps. If you cannot remember what color the patio was sold in, send a photo and we will tell you what is under there.