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Circular and Hazy Stains in Dip-and-Dunk C-41

vicb

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35mm
Hello everyone,

I’ve been running C-41 dip-and-dunk, following all times, temperatures, and concentrations fully within spec. Despite careful workflow, I’ve noticed two types of recurring marks on my frames.

The first are bright circular spots, most often around frame 17. They look like they could originate from the developer—perhaps tiny bubbles formed during agitation that sometimes get trapped under the film. The second are hazy stains, which are clearly re-washable in stabilizer and appear sporadically across different frames. Stabilizer, water quality (I'm using distilled water), and concentrations are all within spec, so I’m not sure why these marks keep returning.

I’m wondering if my agitation might be too vigorous, generating bubbles that cause the bright spots, and what strategies could minimize that. For the hazy stabilizer marks, I’m interested in any workflow tips that prevent recurrence, since everything else seems stable and properly maintained.

Any advice or shared experience with these types of artifacts would be very helpful.
 
Hi, welcome aboard on the Photrio forum! We're happy to have you here.

If you could post some examples of these defects, this would greatly help in troubleshooting the issue.
 
koraks said:
Hi, welcome aboard on the Photrio forum! We're happy to have you here.

If you could post some examples of these defects, this would greatly help in troubleshooting the issue.
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Thank you! I'm happy to be a part of this.

Yes, of course. Here are a couple of examples.
 

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Thanks; these are apparently inverted color negatives; can you also post some clear photos of the defect as seen by the naked eye on the uninverted negatives? It would also be relevant to see a larger section of the frame or even the entire frame to get a better impression of the size of the defect.

So far I think it's interesting that there are several different anomalies and I can't really tell whether they're directly related. There's the donut-shaped one of a higher-density broad ring and a 'normal center, a circular one with a higher-density edge (the last one) and a very strong color cast inside it and also one with a more fuzzy edge to it. My first impression would be that these are distinct failure modes. Do they occur together on the same roll of film, or is there any other indication of these defects being causally related?
 

Thanks for your detailed observations! These are actually from different films, and the anomalies are different problems, though they do reoccur from time to time. Unfortunately, I don’t have photos of the negatives themselves, but I’ll update if the issues show up again.

The hazy one happens most often, and I think it’s related to the stab. The others appear less frequently, and my guess is they’re more likely defaults from the development process.
 
vicb said:
The hazy one happens most often, and I think it’s related to the stab.
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In that case I wonder if it's maybe a drying mark, where a droplet of stabilizer remains relatively long on the film, causing a differential drying rate. This is known to result in permanent optical density differences in the gelatin layer. Do you notice droplets hanging on to the emulsion side of the film as it's being dried?

It's certainly possible that there are multiple causes for these different defects. Air bubbles seem a little less likely for most of them, since most seem to be higher density instead of lower density. Air bubbles tend to show up as lower density circles with a higher density, fairly sharply defined outer rim. On film developed in reels they can also be lower-density blobs with a vague outline as air bubbles trapped in the reel move along the surface of the film; it's typically seen along the edge of 120 roll film in that case. But I don't see how this could occur in a D&D system.
 
Yes, I do notice droplets hanging on the emulsion. Is there any way to avoid this? Could it be caused by the stabilizer itself - I’m using Bellini - or might it be related to the dryer settings? At the moment, the dryer is at 44 °C and the film stays in it for about 30 minutes.

Regarding the other stains, I’m also unsure what could be causing them. They happen very randomly, but almost always on the top frame, so they usually appear in the same position, which makes me think there might be some kind of pattern.
 
You could try turning down the temperature on the dryer to e.g. 30C or so, so that the film dries slower. This might reduce the differential drying rate between the places where the drops hang onto the emulsion vs. the clear space between. You could also test a few rolls by drying them in a normal room environment; there's a decent chance the problem will be gone or much less that way.

It can also help to get rid of as many drops as possible before putting up the film to dry; I understand that wiping the film will not be preferable due to the risk of damage, but perhaps it's possible to shake off as much water as possible before putting them up to dry.

vicb said:
They happen very randomly, but almost always on the top frame, so they usually appear in the same position, which makes me think there might be some kind of pattern.
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I really wouldn't know; maybe splashing in the D&D bath of some kind?
 

Sorry, I didn’t specify earlier, but the dryer is connected to the D&D machine, so I’m not in direct contact with the wet films before they enter the dryer. After taking the films out, I always check them with a magnifying glass, and that’s where I can see the dried droplets on the emulsion side. I guess in this case the only solution would be to try reducing the temperature and see if that helps?
 
Ah, I see. Yes, you could try to reduce the temperature, and perhaps it's also a good idea to reach out to Bellini and present the case to them.
 
If you're getting spots near frame 17, then I'm assuming that's the top loop on the hanger where bubbles can accumulate and cause marks if not properly agitated. It's possible your delay is too long.

Generally the nitrogen gas burst should be 2" every 10" ( raising the solution level by around an inch ).
Gas should ideally go through a humidifier before feeding the tank.

Stabiliser tank can be tricky to get right. Concentration balance is vital.
You may also look into installing a 'wet trough' in the drying cabinet to add some humidity.

John S
 

Thank you, John, for the detailed reply - that makes sense. The marks do line up roughly with the hanger loop area, so bubble accumulation there is definitely a possibility. I’ll review the agitation timing and shorten the delay to see if that helps.

The nitrogen burst spacing is useful to know as well - I am humidifying the gas, but it’s good to have a reference for spacing and solution rise.

Agreed on the stabiliser - it’s been the hardest tank to keep consistent, so I’ll double-check concentration and replenishment. I also wonder whether the fact that agitation is off during the stabiliser stage (I only run it to mix fresh solution) could be contributing as well.

A wet trough in the drying cabinet is an interesting idea - I had thought of that myself, so I’m glad you confirmed it. I’ll definitely give it a try.

Appreciate you taking the time to share your experience!
 
When I saw the initial reference to frame 17, I immediately thought of the frame that is about halfway along a 36 exposure roll of 135 film - so yes, an issue with the hangar loop makes total sense.
Just for clarity, can you confirm that these observed problems are with 135-36 rolls?
 
When the film is loaded onto the hanger, is the film emulsion facing in or out?
 
Yes, exactly! It happens with 135-36 rolls
 
I also have a question regarding the stabilizer. How should I determine when to replace or refresh it during daily operation - based on time, volume, or another factor? Could adjusting this have a positive impact on the staining issue?

Currently, I change it twice a day and use distilled water (for example, when processing around 100 rolls), but should I replace it more frequently depending on the volume of film being processed?
 
John Salim said:
You change it twice a day ! .... are you not replenishing it ?
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I am! Sorry, to clarify: I fill the last bath with distilled water and “stab” in the morning, then change it once more in the afternoon. The 100 films I mentioned would be the minimum. Since I’m not sure what’s causing the stains, I change the “stab” again in the middle of the day. There is also a replenishment involved, but the problem is that the tube injecting the replenishment is on top, so I’m concerned it might not be spreading evenly.
 
John Salim said:
The replenisher tube must feed from the bottom of the tank, so it sounds like there's a length of tube missing.
If it's only fed from the top, you're wasting chemical.
Click to expand...

Thank you for pointing that out!
 
vicb said:
Currently, I change it twice a day and use distilled water (for example, when processing around 100 rolls), but should I replace it more frequently depending on the volume of film being processed?
Click to expand...

John Salim said:
The replenisher tube must feed from the bottom of the tank, so it sounds like there's a length of tube missing.
If it's only fed from the top, you're wasting chemical.
Click to expand...

It sounds to me that this may be your problem. As had been mentioned, you shouldn't have to change the stabilizer tank solution even once a day.

Maybe see how you fare out when you fix the stabilizer tank missing tube and let it replenish at the recommended rate.
 
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