Streaks on B&W emulsion........?

[david_clark10]

Hello all not posted for a while overseas doing some travel images.

Anyway trying to help out a friend in a pro-lab. He is having a prob

with streaks on b&w film for the last few months. The streaks aren't

water marks etc as they can't be washed off after processing even

with wetting agent. They are on the emulsion side and they are

dull/grey in colour (not light fogging). He uses ID-11 with hand

(dunk style / deep tank) aggitation and always has and it is only

present on Ilford 120 film mostly Delta 100 - no others makes 35mm or

120. He can even process Tmax 100 next to a roll of D100 and it is

fine. At the moment he is having to prewash the films in water prior

to development and this prevents the streaks completey. However it

means more handling of the film in the dark and occasional scratches

even with extreme care. So he is looking for a solution - I drew a

blank as did Ilford who have also been contacted (but weren't overly

helpful). Any suggestions would be much appreciated - has the make-up

of ID-11 changed recently? - even a site or forum worth trying - (no

offence to photo.net, its always came up tops for me on advice!)

[jimvanson]

Sounds like bromide drag.<P>Therefor I'd surmise that D100 must require a more aggressive / frequent / over a longer interval "<I>agitation</I>" then TMax 100.<P>Just out of curiosity when you say "<I>he can even process TMax 100 next to a roll of D100</i>". Do you mean side by side or one after another.

[david_clark10]

Yes he can develope any b&w film with the same dev time next to a roll of D100 (ie 2 on 1 rack / side by side). The D100 will be streaked and the other will be fine. What is this bromide drag and is it that the ilford 120 emulsion structure and area just more prone to it? Also what is the cure? thanks for the help.

[dk_thompson]

bromide drag usually happens as an agitation problem in heavily replenished developers. I don't know if this is the problem or not...but I run a deeptank where I work, and years ago we had a problem with certain types of film being more sensitive than others. in the end, we tried prewets and tested at least 3 different developers with control strips & visually checking the film (had been running D76 & D76R). the final fix came with switching to replenished TMAX RS and no prewet. If he can run TMX okay in the same run, I'd try switching out the developer, or possibly starting a new tank. just a thought.

[rowland_mowrey]

Guys;

 

Since bromide is a restrainer, bromide drag causes lighter streaks, not darker streaks when it occurs on film.

 

I agree that it may be agitation dependant, but it may be another problem entirely. For example, exhausted stop or inefficient agitation in the stop can cause uneven streaks on film that would look as you describe. It would depend on the rate of development of a given film, so one film might show it and another might not.

 

In addition, if the problem can be removed by reimmersion in a complete processing sequence, (dev, stop, fix, wash) then the problem was due to retained antihalation dyes or retained sensitizing dyes.

 

The AH dye is usually grey and is washed out by alkali. Sensitizing dyes are removed during the course of the entire process. The mixture of pan sensitizing dyes is often grey. Incomplete removal of these dyes can cause grey stains. Oh, for those who will say AH dyes are on the base side, this is not always true. Sometimes they are actually within the emulsion layer and act as an enhancer to sharpness and are used to fine tune film speed. Sometimes they are in an undercoat below the emulsion layer(s).

 

Hope this helps.

 

Ron Mowrey

[jimvanson]

Ron -- you say "<I>For example, exhausted stop or inefficient agitation in the stop can cause uneven streaks on film that would look as you describe</I>".<P>I'm sorry but I have a <i>really hard time</i> accepting that.<P>Stop -- a step many don't use at all -- should make no difference what-so-ever.<P>Developer problems: yes. Fix problems: yes. But for the life of me stop? I can't see how.<P>Could you expand on your statement?<P>

Ron: I'm not trying to be a smart ass I'm just trying to understand. <P>tkx...j

[rowland_mowrey]

Jim;

 

Stop baths are usually 1% or 2% acetic acid if mixed by the user or lab. If purchased pre-mixed, they also contain some sodium acetate to assist in buffering. Indicator stop baths have an indicator (pH sensitive) dye in them. They are low density solutions.

 

As the stop bath ages, if the acid concentration falls too low, the film just continues developing. The 'mixture' on the surface of the film develops hot spots of developer still reacting, and stop bath shutting developer down. This action, without good agitation, is not uniform, or is 'blotchy' and the film can develop streaks.

 

The way it does this in hanging dip and dunk processors is that the film developer has a far higher density than stop and rolls down the film surface adhering to it. The stop penetrates from the edges of these streaks and begins neutralizing the stop. As a result, you can get vertical streaks of light and dark on the film.

 

It is particularly bad if no stop is used and the film is just rinsed in water with low agitation. This is the extreme.

 

If you go right into hypo, the hypo is more dense than stop, and it contains hardener that tends to 'squeeze' developer out of film by reducing swell. Therefore, sometimes you see this problem with stop or wash, but it goes away with a develop fix sequence. Then as the fix ages, the problem is back and worse than ever due to lack of acid in the fix and bad fixing.

 

You can demonstrate this to your satisfaction this way. Place blank film into a developer in the dark and let the film become saturated. Say about 1/3 of the recommended development time. Use the old method of tray processing with clips for this. Back and forth with a U shaped motion. Then, go into the stop and have someone turn on the lights immediately. You can watch uneven spots develop before your eyes as the stop tries to stop, but the film - developer combination overwhelms it. (this is not an exact science here - you may have to give it several tries to perfect this demo but when done properly, you can see the streaks of developer on the film continue to develop in the light as the stop begins action)

 

Now, in regular film processing the result is not this extreme. It is a faint but definite unevenness or streakiness in film. It depends on the development rate of the film - developer combination, thickness of gelatin layer, etc. It is very complex. That is why you could have two adjacent rolls of different film where one shows the problem and another does not.

 

But, as I said above, this is just one possible cause of the problem. There is a whole list of problems that relate to this including iodide content, thickness, hardness, swell, addenda content, etc.

 

Hope my expanded description helped.

 

Ron Mowrey

[jimvanson]

Ron: Holly Molly, I'll stick with shakin' my tanks!

[david_clark10]

Thanks for the feedback chaps very detailed which helps, I will suggest a dev change if poss (to Kodak maybe) and also dropping the stop and fix (although I expect he has already done this). Any other input welcome thanks!

[rowland_mowrey]

Jim;

 

I developed the original EP2 bleach fix and there was no stop bath in the process. You notice that in that process and RA4 there is a stop. I learned the hard way about stop baths and washes after development. They are a critical step regardless of what the average user may think. I missed a Christmas vacation because of a similar problem in color.

 

Regards.

 

Ron Mowrey

[bernhard]

So in practical terms, for B&W development, what would you recommend:

 

1. No stop at all, going straight to the fix.

 

2. Acid stop prepared fresh all the time

 

3. Do what ever you want but agitate promptly and thoroughly

 

I'm asking because I use an alkaline fix (TF-4) and stopped using acid stop bath to prevent acid carry over to the fix. After developing I just fill the tank with plain water, agitate vigorously, dump the water (takes about 20-30 seconds alltogether) and start fixing.

 

Haven't had problems with streaking yet, so the question is somewhat academic, but if I can prevent running into problems in the future I'll change my routine.

[rowland_mowrey]

Good agitation is the key.

 

Water will do with good agitation. You will see a tiny bit of development in plain water rinse after development and it will vary as a function of water supply.

 

Same with going into alkaline fix. A small amount of continued development which varies with fix exhaustion and water supply.

 

You will get good uniformity though with good agitation.

 

A fresh stop with good agitation stops development and is the most repeatable from person to person and site to site IMHO. Others disagree and state that water or fix is acceptable if agitation is good enough. I cannot disagree if it works for them.

 

Ron Mowrey

[robert_davis2]

I use an alkaline fix and a stop. How? I use a wash after the stop. I do this even with the fact I bet my one shot developer is pretty close to dead by the end of development. What's the downside to my method? Maybe two minutes more work. I'd rather waste two minutes and feel safe.

[eric merrill]

<i>"So in practical terms, for B&W development, what would you recommend:"</i>

 

<p>

I use a couple water baths, with constant agitation. About 30 seconds or so apiece. I'm happy with my results and haven't noticed any difference using a water bath vs. reusing an acid stop. Since I couldn't see a difference, I made my life easier by using one less chemical. :)

 

 

<p>

--<br>

Eric<br>

<a href="http://canid.com/">http://canid.com/</a><br>