Can anyone tell me what plaster burn from acid washing looks/feels like? How much time needs to be spent rinsing the acid in each area once it's done its work removing scale? I am looking at my pool post wash, getting ready to refill, which I think --thanks to reading you all -- I can do myself. But a few areas have some powdery (very light--rub them a bunch and very fine dust left on hand) residue--I was rubbing because they look rougher than most of the plaster--but some areas that are like that were not even done this wash--it was kind of a spot job. They worked in small areas, 3'x4', mainly steps and bench areas. They rinsed each as they went, but not for long periods of time. Just wondering if I should be worrying 
Thanks!
Thanks!