What is the necessity using Chemical Stop Baths?

[photophorous]

Paul I know you mentioned in the other thread about two 30 second water stop baths. Now do you just let water run through your tank or do you fill with water and agitate for 30 seconds each cycle or...?

Immediately after draining the developer, I fill the tank with water and agitate for 30 seconds, about 1 inversion per second, then drain it. Then I do it again, but I'm not as careful to go for a full 30 seconds the second time.

Here's my logic (which could very well be wrong): As soon as you pour in the stop water, any developer that is on the outside of the film will be washed off and diluted to a point where it would take hours to actually effect the development. There is still developer that was absorbed into the emulsion, which will not wash off as easily. The time I spend agitating will remove most of it, but after 30 seconds or so, it's pointless, because that tiny amount of developer remaining inside the film emulsion will have exhausted itself by the time I'm through shaking the tank. So, I suspect a small amount of developing continues in the initial 30 second "stop" wash, but as long as I'm consistent with this process, it is factored in. I've never noticed any visible defects on my negatives, and I've never had a problem with premature death of my fixer. I hope there are no problems that I'm just overlooking.

Paul

[Xia_Ke]

Immediately after draining the developer, I fill the tank with water and agitate for 30 seconds, about 1 inversion per second, then drain it. Then I do it again, but I'm not as careful to go for a full 30 seconds the second time.

Here's my logic (which could very well be wrong): As soon as you pour in the stop water, any developer that is on the outside of the film will be washed off and diluted to a point where it would take hours to actually effect the development. There is still developer that was absorbed into the emulsion, which will not wash off as easily. The time I spend agitating will remove most of it, but after 30 seconds or so, it's pointless, because that tiny amount of developer remaining inside the film emulsion will have exhausted itself by the time I'm through shaking the tank. So, I suspect a small amount of developing continues in the initial 30 second "stop" wash, but as long as I'm consistent with this process, it is factored in. I've never noticed any visible defects on my negatives, and I've never had a problem with premature death of my fixer. I hope there are no problems that I'm just overlooking.

Paul

Thanks for the explanation Paul

I'm curious about something though, are there any effects on final negatives going one way or the other? For example, will using a chemical stop bath give more grain or contrast over a water stop or vice versa?

[mtbbrian]

Thanks for the explanation Paul

I'm curious about something though, are there any effects on final negatives going one way or the other? For example, will using a chemical stop bath give more grain or contrast over a water stop or vice versa?

Now you are getting way over my head!
You might want to ask that on APUG.
Brian

[photophorous]

Thanks for the explanation Paul

I'm curious about something though, are there any effects on final negatives going one way or the other? For example, will using a chemical stop bath give more grain or contrast over a water stop or vice versa?

I've never used a chemical stop bath, so I can't say for certain. But, I don't think grain and contrast would be affected. I suspect there is no difference at all, but if anything, using a water stop bath might equate to adding a few seconds to your development...which you would probably never notice.

I'd be interested to hear from someone who has tried it both ways. Seems like most people just go with what they were taught and don't experiment much with stop baths.

Paul

[Jason Hopkins]

Immediately after draining the developer, I fill the tank with water and agitate for 30 seconds, about 1 inversion per second, then drain it. Then I do it again, but I'm not as careful to go for a full 30 seconds the second time.

Here's my logic (which could very well be wrong): As soon as you pour in the stop water, any developer that is on the outside of the film will be washed off and diluted to a point where it would take hours to actually effect the development. There is still developer that was absorbed into the emulsion, which will not wash off as easily. The time I spend agitating will remove most of it, but after 30 seconds or so, it's pointless, because that tiny amount of developer remaining inside the film emulsion will have exhausted itself by the time I'm through shaking the tank. So, I suspect a small amount of developing continues in the initial 30 second "stop" wash, but as long as I'm consistent with this process, it is factored in. I've never noticed any visible defects on my negatives, and I've never had a problem with premature death of my fixer. I hope there are no problems that I'm just overlooking.

Paul

Paul thats a very interesting and well thought out process. I am inclined to try this with the new developer I have coming in (DiXactol) as its a dye based developer. As previously mentioned I would be a little leary of not using a chemical stop bath with a vigirous developer like d-76 or ID-11. Not to say it wouldnt work just fine...it just gives me pause.