Below are some pics of a job that i did yesterday this is the second job i have done where after cleaning black spots are still visible. The customer again did not want me to use chemicals so it was done with just cold water pressure as i do not have the luxury of a hot washer. I am considering a hot washer for next year but am not sure if hot water alone will still be enough to remove the black spot.
PS the customer was over the moon with the job so i suppose if the customer is happy then i should be happy.