How do you filter your C-41 chemistry?

[Certain Exposures]

Maybe I should step back a bit further. Have you ever needed to filter your C-41 chemistry? If so how did you do it?

I think there could be some sort of fine particulate forming in mine. I can't think of why it would be there. Maybe the tape in 120 rolls leaves it there?

Maybe this explains the dots I see on some negatives. However, the dots appear in a similar spots on the negatives. I doubt the particulate is that petty.

 

[thinkbrown]

Yeah, all replenished chemistry picks up crap over time. I use coffee filters when I'm pouring stuff back in the bottle after a session, seems to do the job for me

 

[gbroadbridge]

Have you ever needed to filter your C-41 chemistry?

Maybe the tape in 120 rolls leaves it there?

I've never seen an issue, however I rinse between every stage so there is very little chemical carryover (which I suppose may cause some unwanted chemical byproducts)

Film should be clean going in, so should be clean coming out the other end with nothing detaching in the processing baths.

I remove the tape from 120 roll film when loading on the reel.

 

[loccdor]

I use the liter kits for about 16 rolls and then toss them. I do more prewashes/intermediate washes between steps than is recommended so my risk of contamination should be reduced.

Other than silver particles collecting in the blix as the kit gets more thoroughly used, hasn't been a problem. I edit out any occasional bright flecks of silver in the image with clone brush. Some people pour their fixer through coffee filters.

 

[koraks]

Have you ever needed to filter your C-41 chemistry?

Nope. I use the developer and fixed one shot most of the time. The bleach doesn't throw down a precipitate. So I've never looked into filtering it. I did at some point have a problem with tiny little spots which turned out to be unrelated to the actual chemistry, but at that point I did switch over to one shot fixer and I never went back (even though it had nothing to do with the problem I ran into, in hindsight). I was already using the developer one shot at that point; I occasionally reuse it once within a short period of time after first use and that's always problem-free.

 

[mshchem]

I'm one shot with developer. I've never fiddled much with filtering photo chemistry. I use demineralized (RO) water for chemistry.

Certainly nothing wrong with filtering. I would use a fast paper filter, qualitative, like the old Whatman #2, I'm sure a coffee filter would be OK.

 

[Mr Bill]

FWIW commercial machines, using replenishment, always have built-in circulation systems (pumps) with replaceable filters. Most common were cylindrical filters with a 20 or 30 micron rating; maybe 10 micron for pickier users. These pretty much collect most of the sludge.

 

[Samu]

The OP does not state what kind of system are we talking about. Is he talking about reusing a liter kit in handheld tanks, or about a replenished, commercial-style system?

 

[gbroadbridge]

The OP does not state what kind of system are we talking about. Is he talking about reusing a liter kit in handheld tanks, or about a replenished, commercial-style system?

He does when he states he leaves the tape on 120 rolls, and wonders if that may be leaving a residue in the chemistry.

Therefore, he is re-using chemistry and processing many rolls with a kit that allows such use. q.e.d.

I do the same, and process 16 rolls with1 litre of chemistry before discarding it.
No problems in the last 20 odd years I've been doing it and I've never found the need to filter the chemistry

 

[Samu]

He does when he states he leaves the tape on 120 rolls, and wonders if that may be leaving a residue in the chemistry.

Therefore, he is re-using chemistry and processing many rolls with a kit that allows such use. q.e.d.

I do the same, and process 16 rolls with1 litre of chemistry before discarding it.
No problems in the last 20 odd years I've been doing it and I've never found the need to filter the chemistry

If this is the case, any residue in chemistry is a reason to mix a new batch. C-41 chemistry costs next to nothing compared to film prices, and trying to reuse beyond capacity is basically ruining a $15 film in order to save 50¢. No developer will produce 16 rolls of film per liter unreplenished, if good quality negatives are desired. The main reason for many of the companies catering to hobbyists are claiming unrealistically high capacities of their chemistry, are the low expectations of folks mainly scanning. You can make an acceptable digital scan from a negative which is quite much off the industry standards. But if you print in a darkroom, this is not the case. Bad negatives are hard to woek with, or in the worst case, good results are impossible to achieve. In replenished systems, such as minilabs, filtering the solutions is necessary.

Hie didn´t say he was using a one liter kit. It is possible to use professional chemistry also in tanks or in rotary systems. That said, replenishing is probably not a viable option in this case for C-41 process.

 

[gbroadbridge]

But if you print in a darkroom, this is not the case.

I agree, but statistically almost no one prints colour in the darkroom anymore 0.00001% does not count.

 

[Samu]

I agree, but statistically almost no one prints colour in the darkroom anymore 0.00001% does not count.

You are exaggerating. Even in Photrio, there are many who do. And I am not the only one. And it is not even very hard, although the "photo club" types said even in the 1980´s it were almost impossible. But yes, unfortunately the young generation is fine with digital files in social media. This is true with any kind of printing photos, irrespective of the technology used.

 

[gbroadbridge]

You are exaggerating. Even in Photrio, there are many who do.

The entire cohort of Photrio probably comprises less than 0.00001% of the folks using CN film worldwide, so that's not much of an argument

Last time I was in a film lab a couple of weeks ago, the lab operator had not even heard of Photrio.

So no, I'm not exaggerating

 

[mshchem]

If this is the case, any residue in chemistry is a reason to mix a new batch. C-41 chemistry costs next to nothing compared to film prices, and trying to reuse beyond capacity is basically ruining a $15 film in order to save 50¢. No developer will produce 16 rolls of film per liter unreplenished, if good quality negatives are desired. The main reason for many of the companies catering to hobbyists are claiming unrealistically high capacities of their chemistry, are the low expectations of folks mainly scanning. You can make an acceptable digital scan from a negative which is quite much off the industry standards. But if you print in a darkroom, this is not the case. Bad negatives are hard to woek with, or in the worst case, good results are impossible to achieve. In replenished systems, such as minilabs, filtering the solutions is necessary.

Hie didn´t say he was using a one liter kit. It is possible to use professional chemistry also in tanks or in rotary systems. That said, replenishing is probably not a viable option in this case for C-41 process.

Very well said. Absolutely no reason to overuse C-41. Such false economy. I still print color, it's something that I do rarely, but it's fun. I certainly want everything I can get out of the Ektar and Portra I shoot.

I bought a couple rolls of the Harman Phoenix, I didn't try to print or scan. It's funny looking stuff.

It's whatever you enjoy. Just don't waste valuable film and time on crappy chemistry.

PS the bleach gets reused and replenished, it's almost eternal!

 

[Samu]

The entire cohort of Photrio probably comprises less than 0.00001% of the folks using CN film worldwide, so that's not much of an argument

Last time I was in a film lab a couple of weeks ago, the lab operator had not even heard of Photrio.

So no, I'm not exaggerating

Yes, nut for most of people shooting CN, the capacity of chemistry is also irrelevant, because they take their films to commercial lab for developing and printing and/or scanning. What I mean with all of this, is that I would like to know the exact process the OP is using, in order to understand the problem.

 

[koraks]

I would like to know the exact process the OP is using, in order to understand the problem.

That's always a good starting point, combined with some insight into requirements of expectations in terms of the resulting negatives.

 

[Certain Exposures]

Thanks everyone. I'll follow up on this over the weekend. I am knee-deep in another problem at the moment.

 

[Certain Exposures]

What I mean with all of this, is that I would like to know the exact process the OP is using, in order to understand the problem.

@Samu @gbroadbridge @mshchem please see below.

My developing process:

1. I heat the tank to 104 degrees in a temperature-controlled water bath.
2. Then, I develop the film outside of the water bath using the upgraded version of this rotary processor to complete the developer and blix baths. I do not use a stop bath or a water wash between steps.
3. I skip the final stabilizer bath because the instructions say that modern films do not need it.
4. I use 8 ml of wetting agent in a 1000mL beaker of distilled water to soak the film for 2 minutes with mild agitation for the first 15 seconds. I have not been satisfied with less wetting agent or shorter soaking times. I experimented.
5. I often reuse the chemistry for months at a time. I develop a test strip first if I reuse the chemistry after a long break. I have never printed color film in the darkroom. I will start when I am much older, so I suppose I should think about this.
6. Here's an example of a 120-frame I developed in chemistry I reused several times. I have never seen the dot problem I am trying to solve on a roll of 120 film. It only appears on recent rolls of 35mm film.

Exhibit 1 (Note: Photrio removed my in-line preview of the image...I don't know why.)
View attachment 414033
Mamiya RB67, 645 film back, Kodak Gold 200 @ box speed. I forgot the lens. It might be the K/L 127mm.

Nope. I use the developer and fixed one shot most of the time. The bleach doesn't throw down a precipitate. So I've never looked into filtering it. I did at some point have a problem with tiny little spots which turned out to be unrelated to the actual chemistry, but at that point I did switch over to one shot fixer and I never went back (even though it had nothing to do with the problem I ran into, in hindsight). I was already using the developer one shot at that point; I occasionally reuse it once within a short period of time after first use and that's always problem-free.

@koraks could you please share what the problem was that caused the tiny little spots and how you solved it?

 

[MattKing]

I skip the final stabilizer bath because the instructions say that modern films do not need it.

Depends on the stabilizer.
Modern "Final Rinse" is different from the older stabilizer.
The older stuff did three things - it helped stabilize the dyes, it added a bactericide that helped prevent bacteria from damaging your film over time, and it provided a surfactant to aid clean drying.
Subsequently, manufacturers like Kodak moved the part that helped stabilize the dyes into earlier parts of the process. So modern "Final Rinse" does just the final two things: it adds a bactericide that helped prevent bacteria from damaging your film over time, and it provided a surfactant to aid clean drying.
Your procedure omits the bactericide.

 

[Certain Exposures]

Your procedure omits the bactericide.

I don't recall the instructions mentioning that by omitting it I've allowed my film to turn into a meal.

Disappointing.

Thanks.

 

[MattKing]

It is a very slow meal!
FWIW, you can rewash and use "Final Rinse" thereafter.
"Final Rinse" is/was Kodak's name for it.
You can see it on the instruction sheet for the new C41 kits from the new manufacturer, PhotoSys: https://kodak.photosys.com/collections/kodak-co/products/kodak-color-negative-c-41-kit-2-5l
Here is the link to that instruction sheet: https://cdn.shopify.com/s/files/1/0339/5113/files/KODAK_C41Kit_2024-V1_EN.pdf?v=1723833370

 

[Helios 1984]

It's been a while since I've done colour developing but, usually, I filter the developer with a coffee filter before processing a roll. A few weeks back, I purchased an old Paterson Photo Filter System which will what I'll use next time I process a roll.

 

[Certain Exposures]

Thanks @MattKing , @Helios 1984 .

Just noting here that I developed some black and white film in the same Patterson tank. It was spotless.

I used the same camera, a different lens, fresh developer, fresh stop bath, re-used fixer, re-used hypo wash, and the same scanner.

Maybe I should step back a bit further. Have you ever needed to filter your C-41 chemistry? If so how did you do it?

I think there could be some sort of fine particulate forming in mine. I can't think of why it would be there. Maybe the tape in 120 rolls leaves it there?

Maybe this explains the dots I see on some negatives. However, the dots appear in a similar spots on the negatives. I doubt the particulate is that petty.

I should be able to rule out a camera body issue. So it could be the C-41 chemistry, a lens filter, or the lens.

I will probably get fresh C-41 chemistry due to the conversation about printing and test that using the appropriate lens and lens filter.

 

[Certain Exposures]

I reused my C-41 chemistry for the 5th time this month. It was just for a black and white test roll.

I held the developer up to a strong light before using it. The fluid in the bottle had the consistency of chicken noodle soup thanks to some unknown substances floating inside it...

I decided to use a mesh strainer on the developer, stop bath, and blix. I didn't see anything trapped in the mesh so I suspect that I have to try something finer. However, the developer looked clear after I rebottled it? Strange. Maybe the mystery bits will reappear later.

 

[koraks]

The fluid in the bottle had the consistency of chicken noodle soup

Color, or also actually consistency? Chicken noodle soup in my imagination would be not quite as runny/liquid as water and slightly more viscous. Whatever happens, a C41 developer should never become viscous; for this to happen, it would have to be seriously contaminated with something probably organic. I've never seen it happen, not even in used C41 developer I have let sit for weeks.
Here's a bottle I coincidentally have had around for way too long (maybe a month or so?)

The color appears a little lighter in reality; the phone snaps are underexposed. 90% of the color is of the dyes of the film developed that soak into the developer. As you can see, the liquid is perfectly clear. There's no sedimentation, floating muck etc. The spots on the second pic are just finger prints on the outside of the bottle. This developer was used once or twice; probably once. I rarely use C41 developer twice.

If you set the bottle on a counter for a week or so, all solids will settle at the bottle. If you then gently move or tap it, you should be able to see the stuff kick up from the bottom, which will give some insight into what kind of particles there are.