Once all the Black Spots have turned White you are then ready to rinse the chemical off. It is very important that you do this carefully and safely, we DO NOT advise rinsing straight off with a pressure washer! This will produce airborne spray of neat chemical which if comes in contact with sensitive areas could cause damage. We STRONGLY recommend rinsing thoroughly with a hose first, this can be done safely. There after once all of the cleaner has been rinsed away you can then use your pressure washer to removed all the White Spots and thoroughly clean the patio.