patio slabs outside best course of action.

Graham fallows

Cleantalk Member
cleaned some flagstones this morning in a pub the landlord asked me if I had and solution left could I do a test area in the smoking area outside.
he as previously power washed the area but was not happy with is final result still lots of black shadowing where the pattern lifts in areas all I used today was grout blaster freshly made up I still struggled with the raised bits, i used a 17 inch rotary plus two grout brushes different sizes I still had final phase rinse in the tank, I did have sts on the van but didn't think of it at the time.
i posted some pics of test area it looks in the pics as thou there are white salts/powder forming on the slabs could it be the rinse, I don't normally clean outside could course of action be rotary clean then power wash off rather then wet rinse I'm hoping someone as got some suggestion sorry its a long one thankyou graham.