PDA

View Full Version : BW Development > What time can I switch the lights on?



l2oBiN
31-Aug-2010, 13:52
I am in the process of developing my first BW photo. At what time point can I switch the lights on? As soon as it hits the fixing step?

Pawlowski6132
31-Aug-2010, 14:07
As soon as it's out of the stop.

bob carnie
31-Aug-2010, 14:13
No

give it at least 30 seconds to take hold in fix.
for final prints I do not turn on the lights until after 2mins.

As soon as it's out of the stop.

l2oBiN
31-Aug-2010, 14:15
let me be more clear, I am developing my first BW negative. When can I switch the lights on?

bob carnie
31-Aug-2010, 14:18
Then I would wait until a few minutes go by using a good fresh fix.

You can tell the fixing time by dipping a piece of film into your fix and seeing how long it takes to clear, I would then double or triple that time to be safe.

l2oBiN
31-Aug-2010, 16:29
Hmm. i am still unclear on this matter. Do I need to keep it in the dark while its in the fix?

sanking
31-Aug-2010, 16:31
Hmm. i am still unclear on this matter. Do I need to keep it in the dark while its in the fix?

No, once the film is in the stop bath, assuming a fresh and normal strength acetic acid stop bath, you can turn the lights on. No more development will take place once the film has been in the stop bath for 10-15 seconds.

Sandy King

Sirius Glass
31-Aug-2010, 17:17
What Sandy said if you are talking about regular lights; the safe lights can be on all the time.

Steve

Lachlan 717
31-Aug-2010, 17:25
What Sandy said if you are talking about regular lights; the safe lights can be on all the time.

Steve

Not for film.

Brian Ellis
31-Aug-2010, 18:01
When I used the BTZS tubes I turned the room lights on when I started developing. If you're using trays you should wait until the film hits the stop bath.

JRFrench
1-Sep-2010, 00:24
Another count for lights on when the film is in the stop bath. As an experiment with paper you can turn the light on when its in dev, and watch it darken, then move it to the stop and watch it immediately stop darkening, quite interesting.

Tom Monego
1-Sep-2010, 05:42
Not sure about turn lights on when the film is in the stop bath, if it is not strong enough some residual development could take place, if it is too strong stop can react with developer accelerators (bases) to cause damage to the film. A lot of folks on this list seem to use a water bath rather than an acetic acid stop bath, in that case don't turn on the lights.
I have generally waited until the fix is finished when using a tank, 30 seconds to one minute in fix when using trays. Really think the safest is to wait until the fix has done some action. BTW I have turned on the lights while paper is in the stop (acetic acid) and gotten some fogging.


Tom

jp
1-Sep-2010, 06:15
Stop bath takes time to do it's thing. It's not an instant process. If your instructions say to have it in the stop for 30 second, it's because it might need 30 seconds to totally stop the development (remove or neutralize the developer).

I know I've turned the lights on with test strips of paper freshly put into the stop bath and seen ghostly darkening of the strip because of the lights coming on while it sat in the stop bath. This is a more telling experiment than JRFrench's still interesting test.

For paper, I am comfortable turning the lights on 15 seconds after it's in the fixer. For film, I'm comfortable after 2-3 minutes of fixing.

DanK
1-Sep-2010, 06:16
I prefer to not take chances with film, I'd suggest waiting to turn on any lights until the fixer step is complete - full recommended length of time.

Thanks,
Dan

Brian Ellis
1-Sep-2010, 09:27
"After development the negative is transferred to a stop bath, which serves several functions: (1) since it is acidic, it neutralizes the alkaline developer remaining in the emulsion, thus immediately arresting development. . . . " (emphasis added) Adams, "The Negative" p. 190. He then goes on to discuss the purpose of the fix, which isn't to further stop development (since the stop bath has already accomplished that) but rather is to remove unreduced silver halide remaining in the film after development which if not removed would eventually cause staining or bleaching of the film.

If those who wait until film hits the fix or has been in the fix for some time before turning on the lights feel more comfortable doing that, that's certainly fine for you and I wouldn't try to change your practice. But the OP shouldn't be mislead into thinking that it's necessary or even useful to wait that long. I turned on the darkroom lights as soon as the film hit the stop bath for many years because I never liked standing around in the dark and have never had any problems from doing that.

Mark Stahlke
1-Sep-2010, 09:58
I prefer to not take chances with film, I'd suggest waiting to turn on any lights until the fixer step is complete - full recommended length of time.This.
What's the rush? If you can't wait a couple of minutes to see your negatives then you may not have the patience for LF photography.

arunrajmohan
1-Sep-2010, 11:17
I do tray development and I switch on the light after 2 minutes of continuous agitation in the fix. I do not agree with the suggestion that the film can be exposed after the stop. Stop stops the action of the developer on the chemicals (that have been exposed to the light) and that does not mean that all of the silver on the film has become light insensitive. Fixing takes care of the remaining silver that is sensitive to the light by removing it off the film. Hence I believe that at least a few minutes in the fixer (3 minute minimum is suggested by Ilford for its rapid fixer) is a must before the film is exposed. As for the safe light, one must take the film sensitivity into consideration. High iso films are not safe with safe light. While most print papers and films like EFke 25 do not mind the safe light.

Bruce Barlow
1-Sep-2010, 11:59
I wait until 3 minutes into a five minute fix. What's the rush? And at that time I'm SURE it's safe.

jp
1-Sep-2010, 16:35
Develop 4 4x5 sheets of paper of an identically exposed high key image. Drop each into the stop bath at 3 second intervals, then immediately turn the lights on. That will show you it is certainly not an instantaneous process to stop development with stop bath. The last couple of sheets will get a dark shadow on them as the developer hasn't been neutralized yet.

Brian Ellis
1-Sep-2010, 16:58
I do tray development and I switch on the light after 2 minutes of continuous agitation in the fix. I do not agree with the suggestion that the film can be exposed after the stop. Stop stops the action of the developer on the chemicals (that have been exposed to the light) and that does not mean that all of the silver on the film has become light insensitive. Fixing takes care of the remaining silver that is sensitive to the light by removing it off the film. Hence I believe that at least a few minutes in the fixer (3 minute minimum is suggested by Ilford for its rapid fixer) is a must before the film is exposed. As for the safe light, one must take the film sensitivity into consideration. High iso films are not safe with safe light. While most print papers and films like EFke 25 do not mind the safe light.

Fixing removes unreduced silver halides (i.e. the silver halide crystals that weren't reduced to metallic silver by the developer) that remain in the film emulsion after development. If these halides weren't removed they would, over a relatively long period of time, cause stains or bleaching in the film. But the halide crystals that have already been converted to metallic silver (i.e. the image forming crystals) are no longer affected by light once development is arrested by the stop bath, i.e. metallic silver is metallic silver, it doesn't become any "more" metallic silver by exposure to light after that point. And even the staining or bleaching that fix prevents isn't going to happen in the few seconds of exposure to light that occurs while the film is in the stop bath.

So no, a few minutes in the fixer before turning on the lights isn't a "must." If it was I would have ruined at least a thousand sheets of film.

Brian Ellis
1-Sep-2010, 17:06
I wait until 3 minutes into a five minute fix. What's the rush? And at that time I'm SURE it's safe.

No rush. If you feel better by standing around in the dark for 3 minutes for each batch of film you process that's fine. I didn't like doing that myself and since I knew it was unnecessary it didn't make me sure of anything. But the OP asked when lights could be turned on. Based on my understanding of what happens when film is immersed in a stop bath and then in the fix, and on my experience in processing at least a thousand sheets of film, it would be incorrect to tell the OP that he must do what you do. He may choose to do what you do and if so that's perfectly fine. But three minutes into the fix isn't the earliest point at which lights can safely be turned on.

John Bowen
1-Sep-2010, 18:09
I always turn the darkroom lights on at quarter past ten.....sorry, I just couldn't help myself....

Sirius Glass
1-Sep-2010, 18:24
What Sandy said if you are talking about regular lights; the safe lights can be on all the time.

Steve

Not for film.

Opps! :o My bad! Sorry!

Andrew O'Neill
1-Sep-2010, 19:06
I am in the process of developing my first BW photo

Are you talking about developing film? If so, I flick on a bright safe light once the film is in the stop. After 30 secs in the fix, the house lights go up.

David Woods
2-Sep-2010, 00:49
Is someone scared of the dark?

Sorry couldn't resist

l2oBiN
2-Sep-2010, 00:56
Hmm so there is am array of answers here from as soon as it hits to stop bath to after it's finished fixing. Isn't the fix meant to "fix" the negative so it cannot be influenced by light?

Darin Boville
2-Sep-2010, 01:38
No lights for me until halfway through the fix--no peeking!

--Darin

archer
2-Sep-2010, 02:22
I agree with Bruce and Darin especially if you are using a water rinse instead of an acid stop bath and an acid free fix which is customarily used with a staining developer. What's the hurry? You still have to stand there to fix to completion anyway, lights on or off.
Denise libby

sanking
2-Sep-2010, 08:53
Hmm so there is am array of answers here from as soon as it hits to stop bath to after it's finished fixing. Isn't the fix meant to "fix" the negative so it cannot be influenced by light?

Yes, many answers. But if the question is "when it is safe to turn on the lights" the best answer is that of Brian Ellis. It is safe to turn on the lights as soon as the film goes into the stop bath. People can give all the opinions they like but it won't change the fact, and the fact is that all development is arrested within several seconds of the film hitting the stop bath. For long term stability the film must also be fixed, but that is another matter.

Now if anyone just likes to stand there in the dark until the film comes out of the fixer they should feel free to do so.

Sandy King

venchka
3-Sep-2010, 09:59
Call me old fashioned. Since switching to Jobo tanks & drums, I don't open them until I'm ready to dunk the negatives in Photo-Flo.

Otherwise, after reading the above and allowing for some of us who use a tap water "stop" bath, turning the lights on after 1 or 2 minutes in the fixer should be harmless. Any earlier and there isn't too much to see.

cowanw
3-Sep-2010, 11:51
I am wondering if it makes a difference if you plan to bleach and redevelop.
In theory exposure to light before fixing would leave a latent image which would be available to a second developer and would come up as fog.
Regards
Bill

Darin Boville
3-Sep-2010, 13:09
Any earlier and there isn't too much to see.

Exactly. Plus it is nice in the dark :)

--Darin

Doremus Scudder
4-Sep-2010, 04:24
Just to add some variables to this conversation:

First, yes, if you have an active and fresh acid stop bath, it only takes a few seconds to stop development. But it is safe to turn on the lights at this time only if you are using an acid fix, which keeps the pH at a level where carried-over developing agents cannot be reactivated and start to develop the halides exposed by the room lights.

The pH change in the emulsion keeps the developing agents from working once the stop soaks in. However, the stop bath does not remove them completely in 30 seconds. If you use an alkaline fix, you run the risk of the carried-over developer being re-activated, which can cause fogging and streaking. (yes, I've had it happen to me and it is one reason I switched back to an acid fix).

Although a fresh stop will inhibig most developing agents, some are more robust than others. Also, if your stop is exhausted or if you stop too short and then put your film into an alkaline fixer with the lights on... well, the risk of fogging is increases.

If you use an alkaline fix (especially if you use a water stop), then you had better not turn on the lights until the fixing stage is almost complete and there is no more light-sensitive silver halide in the emulsion, since there may be active developer now lurking in your emulsion!

If, however, you use a fresh acid stop and acid fix, you can turn on the lights after just a few seconds in the stop and not risk any carried-over developer being re-activated.

Best,

Doremus Scudder

Bill Burk
4-Sep-2010, 23:36
I wait until fix is complete because if I turn the lights on when I drop it in the fix then I'll want to see them if they're negs. If they're rolls, I'm going to unreel them and run fix up my shirtsleeves to my elbows. Plus there's a risk I'll scratch the film trying to re-reel it wet. And the fixing will be uneven since I lost track of what I was doing. That's just if I don't get distracted with the lights on and walk away for a half hour.