Quote Originally Posted by SMBooth View Post
Is there any problem using hydrochloric acid instead? its available from Bunnings.
You can't use HCl because the chloride would convert the silver image form insoluble Silver chloride which wouldn't wash out before the reversal stage. You'd be forming a re-halogenating bleach, this is why Sulphuric acid is used as the Silver Sulphate formed during bleaching washes out of the emulsion.

Ian