Stop bath should be 2% acetic acid. The dilution directions on Kodak 28% acetic acid say "...dilute 6 ounces in 1 gallon of water for a working solution." What I normally do is add the 16 ounce bottle of 28% to 38 ounces of water and then dilute that "stock solution" at a ratio of 9 parts water to 1 part stock solution (100ml stock solution and fill graduate to 1000 ml).(posted 9297 days ago)