How Soon Would Chemical Burns Show Up on the Scalp?

me and my partner have a hair and beauty salon, and we recently had a client in to have some blond steaks in her hair. The colour wouldn’t lift the first time so it was applied for a second time. She had a rash on her scalp when she came in so we checked with her all the way through the treatment that she wasn’t experiencing any discomfort and her scalp was checked several times before she left the salon. but she has scince told us that she has recived bleach burns. i was always under the impression that it would be painful and that signs would show very quickly. Would we not have seen a problem while she was at the salon.

Sometimes the burn that has worked its way to the base of the hair follicles will not cause pain and not show up for 1-3 weeks. The hair will fall out if it is burned chemically.