Thanks blast away that's exactly was I was getting at, yes without chems you could probably got the same results however with the amount of pressure would have had to use the whole wall would have needed to be rebuilt.
Great outdoors I don't think you get where I'm coming from I don't need chems for everything I do as the kit I have does the job, the spec is higher than your average pressure washer.
What I'm interested in is hypo, or any other chem to help finish off a job well done by removing the black spots etc.
Bdcs and blast away do you think oxygen bleach would do the job as well? I understand it may take longer but like I say I wouldn't need it all the time so would need something I could store.
Many thanks,
Gordon