Likewise, it’s advisable to use a fan nozzle rather than a jet. The fan sweeps out a greater area, making it easier to get an even final colour, and makes for faster work too. It’s also easier to accidentally damage your concrete while cleaning with the greater pressure of the jet, so there’s little advantage to using it.
If, however, you’re struggling to find a washer with enough pressure, you can buy a rotating nozzle to boost the effective pressure of the water. These achieve the same effect as a fan nozzle but without deflecting the water, so that no momentum is lost.
Safety warning: 20 MPa is a lot – it’s more than twice the pressure of a stiletto heel! So handle the washer with care, wear eye protection, and always follow the manufacturer’s instructions carefully. We don’t want any injuries!
How to remove oil stains from concrete
If there’s an especially heavy oil or grease stain – as can so easily happen if you own a vehicle or just love carrying buckets of oil around – then take some clean cat litter or fine sawdust, and cover the stain with it before washing. Then, leave it overnight. This takes some time, but should draw the worst of the oil up out of the concrete, ready for it to be brushed away.