New guy here in my way to develop second roll of film ever. I was reading that if I use Ilford Rapid Fixer I don't need to use an acidic Stop Bath. Is that correct?
Thanks.
Most developers work in an Alkaline environment, so stop bath being an acid will cause the development to stop, quickly. This is needed with paper which typically has a very short development period, sometimes as short as 30 seconds. As the development time gets longer, rapidly stopping development becomes less and less critical, so an acid stop becomes less critical. Where stop bath can help is it helps your fixer to last longer. Each chemical carries over into the next, using stop bath means that the stop bath, rather then developer carries over. Developer carried over into the fixer will shorten the life of the fixer. If you use a neutral or slightly alkaline fixer, then as more and more developer carries over, development can continue slightly and you will become bald from tearing your hair out wondering why your getting uneven development. The rule really should be, if you use your fixer one shot then use the water stop, if you want to reuse your fixer, then use the stop bath. Even so, stop bath isn't that critical, and if you run out, it's not a show stopper, like you would get if you ran out of developer or fixer.
One thing that is recommended though, if you reuse your fixer, do a clip test to determine if it's still good, for every session. Here is how you do it, with 35mm, when you clip off the tongue, keep it to the side, do not develop it, put a drop of fixer on it, wait 30 seconds, then drop the piece into a small dish of fixer, time how long it takes for the spot to disappear. When using freshly mixed fixer, write the time on the bottle. This is your initial clear time.
Next session you do this test again, you will notice the clear time gets a little longer, when it gets to double the original time you wrote on the bottle, dump it and mix fresh. To determine fixing time, double the clear time, and round up to the next minute, so if your clear time is 45 seconds, double that is 90 seconds or 1½, so you would fix for 2 minutes. If your clear time is one minute, double is 2 minutes, fix for 3 minutes. If the initial clear time was 30 seconds, then when your clear time gets to 1 minute, you mix fresh fix. Using this method means that if you use a different brand or type of fixer, you still know the fixing time.