Magenta cast in self-developed C41

Hi, I recently purchased my first set of C41 chemicals and started processing and scanning my own color film using a Paterson tank and a Coolscan LS-50. I had my local lab mix up around 1.5L of official Fujifilm CN-16 chemicals (working tank mixes of the N1 developer, N2 bleach, N3 fixer, and N4 final rinse chemicals). I have been using a process that looks like this:

• Start a sous vide bath set @ 115F in a plastic tub, and place 600 mL glass beakers containing developer, bleach, fixer, and water. I have an analog thermometer in the beaker containing developer.
• When the developer approaches 101F, I dump the heated water into the Paterson to heat the tank, I then place the Paterson tank in the heated bath. I also remove the bleach and fixer beakers from the bath since they are warm enough for the rest of the development process.
• After a few minutes, I dump the water back out.
• I then develop for 3m 15s, 30 initial inversions, 2 inversions every 15s afterwards. Between each set of inversions, I put the Paterson in the heated bath to prevent cooling of the developer.
• Bleach for 6m 30s, 30 initial inversions, 5 inversions every 30s afterwards
• Rinse under running water (completely changing water a few times) for 5 minutes
• Fix for 6m 30s, 30 initial inversions, 5 inversions every 30s afterwards
• Rinse under running water (completely changing water a few times) for 5 minutes
• Stabilize for 1m 30s, 30 initial inversions, no subsequent inversions

The first 10 or so rolls came out great with no color casts. The negatives and scans looked good (on par with lab processed and scanned rolls). However, as I continued developing, I started seeing a magenta cast in the scans and the negatives seemed kind of green. To verify that this wasn't due to a single roll, I ran about 3 rolls, however each resulted in a strong magenta cast in the scans/greenish negatives. Reading PE's old posts, it seemed that I could be underdeveloping with insufficient development of the magenta dye. I had been told by the lab to keep development time the same for each roll and to only increase development time by 10% after the chemicals reached 3 weeks (they're 2.5 weeks old at the moment), but this seemed incorrect after reading instructions for consumer kits like Tetanol and Cinestill. I tried increasing development time yesterday to 3 minutes 40 seconds (this is now rolls 17 and 18), and while this resulted in a negative with better contrast, there was still a magenta cast. I then tried increasing development time to 4 minutes 40 seconds (this is now roll 19) today but am still getting a magenta cast. The cast corrects easily with Silverfast or Negative Lab Pro (if I export as RAW and invert in Lightroom), but I would like to identify and fix the root cause. I uploaded a picture of two negative strips (left was before this problem appeared, and right was the roll from today). I have also uploaded non-color corrected prescans from Silverfast of a shot from each strip. I was wondering if I need to extend development time even more, if my developer is exhausted, or if it was contaminated (I noticed that the developer is quite foamy after development so I wonder if this is due to residual stabilizer from the tank, but I do wash my equipment thoroughly).

Negative strips (earlier roll on left, roll from today on right, roll from today seems greener compared to roll from earlier, both are of Kodak Gold 200):


Negative on left (earlier roll, no color cast):


Negative on right (roll from today, magenta cast):

Lucas Yan said:

or if it was contaminated (I noticed that the developer is quite foamy after development so I wonder if this is due to residual stabilizer from the tank, but I do wash my equipment thoroughly).

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A couple of points:

• I always put film through final rinse or stabilizer steps off the reels as I've had problems in the past.
• When kept as replenisher solution, the C-41 developers last a long time in tightly capped containers (many weeks at least) - perhaps there is an issue with keeping the working solution (dev rep. + starter + additional water) for an extended period of time.

@Tom Kershaw Thanks for the suggestion, do you still agitate for your final rinse or do you let the film sit as-is in the stabilizer for a few minutes? I know working developer doesn't last as long as concentrates or replenisher, but 2.5 weeks seems like a reasonably short amount of time considering that most home C41 kits list a lifetime of 4 weeks for the developer. I am planning to switch over to Flexicolor in the future though so I can do a replenishment model instead.

Lucas Yan said:

do you still agitate for your final rinse or do you let the film sit as-is in the stabilizer for a few minutes?

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I very gently pull the whole film through a "trough" of solution (e.g Pyrex jug)

On the other point, I've got on very well with my first batch of the Fuji Hunt Environeg developer, although I have previously used Flexicolor. I use a Jobo for colour processing and from first hand experience would not recommend replenishing C-41 developer for rotary machines; however your inversion method may work fine as there is more solution and probably less oxidation. Bleach and fix I certainly do re-use / replenish - capacity of bleach is huge.

This chemistry, the older it gets, the more problems it creates.
The chemistry that contains the Replenisher solution is mainly intended for professional machines and not intended for home development,
The professional machine is dedicated to the development of huge quantities per hour, and everything is done in an automated way.
- But home development, no matter how much rolls you will consume, it must not exceed 10 rolls per day.
This is my personal opinion, with all due respect to all others.
In general, I advise you to do the following:
I'm talking about the developer only, not the rest of the solutions.
First, disposal of the working solution and preparation of a new working solution.
After using the new mixture, store this solution in an airtight brown or blue glass bottle. And store it in the refrigerator.
All steps must move and be agitated (except
pre-soak step)
I never admit that it can not be instigated.
All steps must be instigated.
I do the agitation on my own curriculum. Every 30 seconds, I agitate 10 turns to the right and 10 turns to the left.
The agitation during washing is continuous without stopping 10 laps to the right and 10 laps to the left without stopping.

Lucas Yan said:

Hi, I recently purchased my first set of C41 chemicals and started processing and scanning my own color film using a Paterson tank and a Coolscan LS-50. I had my local lab mix up around 1.5L of official Fujifilm CN-16 chemicals (working tank mixes of the N1 developer, N2 bleach, N3 fixer, and N4 final rinse chemicals). I have been using a process that looks like this:

• Start a sous vide bath set @ 115F in a plastic tub, and place 600 mL glass beakers containing developer, bleach, fixer, and water. I have an analog thermometer in the beaker containing developer.
• When the developer approaches 101F, I dump the heated water into the Paterson to heat the tank, I then place the Paterson tank in the heated bath. I also remove the bleach and fixer beakers from the bath since they are warm enough for the rest of the development process.
• After a few minutes, I dump the water back out.
• I then develop for 3m 15s, 30 initial inversions, 2 inversions every 15s afterwards. Between each set of inversions, I put the Paterson in the heated bath to prevent cooling of the developer.
• Bleach for 6m 30s, 30 initial inversions, 5 inversions every 30s afterwards
• Rinse under running water (completely changing water a few times) for 5 minutes
• Fix for 6m 30s, 30 initial inversions, 5 inversions every 30s afterwards
• Rinse under running water (completely changing water a few times) for 5 minutes
• Stabilize for 1m 30s, 30 initial inversions, no subsequent inversions

The first 10 or so rolls came out great with no color casts. The negatives and scans looked good (on par with lab processed and scanned rolls). However, as I continued developing, I started seeing a magenta cast in the scans and the negatives seemed kind of green. To verify that this wasn't due to a single roll, I ran about 3 rolls, however each resulted in a strong magenta cast in the scans/greenish negatives. Reading PE's old posts, it seemed that I could be underdeveloping with insufficient development of the magenta dye. I had been told by the lab to keep development time the same for each roll and to only increase development time by 10% after the chemicals reached 3 weeks (they're 2.5 weeks old at the moment), but this seemed incorrect after reading instructions for consumer kits like Tetanol and Cinestill. I tried increasing development time yesterday to 3 minutes 40 seconds (this is now rolls 17 and 18), and while this resulted in a negative with better contrast, there was still a magenta cast. I then tried increasing development time to 4 minutes 40 seconds (this is now roll 19) today but am still getting a magenta cast. The cast corrects easily with Silverfast or Negative Lab Pro (if I export as RAW and invert in Lightroom), but I would like to identify and fix the root cause. I uploaded a picture of two negative strips (left was before this problem appeared, and right was the roll from today). I have also uploaded non-color corrected prescans from Silverfast of a shot from each strip. I was wondering if I need to extend development time even more, if my developer is exhausted, or if it was contaminated (I noticed that the developer is quite foamy after development so I wonder if this is due to residual stabilizer from the tank, but I do wash my equipment thoroughly).

Negative strips (earlier roll on left, roll from today on right, roll from today seems greener compared to roll from earlier, both are of Kodak Gold 200):
View attachment 283434

Negative on left (earlier roll, no color cast):
View attachment 283435

Negative on right (roll from today, magenta cast):
View attachment 283433

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You can get rid of this purple haze in a smart way using the VieuScan scanner app - this app has some features that enable you to get rid of the extra red and extra blue, so you will be able to equalize and adjust the image colors.
Do not forget to choose the color channel (Autocolor). From the list of colors.

@mohmad khatab That makes sense, do you know if the Fuji Hunt consumer kit is formulated differently than the Fuji Hunt commercial chemistry? I used the instructions, capacity, and lifetimes from the consumer Fuji Hunt 5L kit, but if the minilab chemicals are indeed different, then it would make sense why I was seeing a significant drop-off around roll 14.

I usually use VueScan to create a RAW which I then bring in to Negative Lab Pro (I used the Silverfast demo only to verify that the purple cast was not due to a VueScan or Negative Lab Pro error). I am able to get rid of the magenta cast easily in Negative Lab Pro by moving the magenta slider of the shadows and midtones toward green (since the magenta cast is due to a lack of magenta dye).

my dear brother,
Don't trust too much in the maker's instructions, these instructions were written by a human being, that is, they are not a book sent down from heaven.

I told you my personal opinion.
My view may not be perfect.
But I was never convinced that these kits can be used for home development,,
- I advise you to prepare your own chemistry with your own hands from scratch..
I rediscovered an old formula that was neglected and I can tell you about it and it is very cheap and you can prepare only half a liter and this half a liter you can use to develop six rolls.
And these are some of those pictures that were produced in that crazy format.
In general, undoubtedly, you should first and foremost consume all the quantities of chemistry you have before thinking of any other direction.
The quantity you have in your home must be used as you have purchased it, and you should not waste chemistry or money,,

@mohmad khatab These are nice pictures. I am aware of being able to mix your own developers (someone bought a set of chemicals and mixed ECN-2 developer to Kodak's spec and wrote an article about it), but unfortunately I don't have the lab-grade equipment required to do this myself (pH monitoring, specific gravity measurements) or the appropriate auxiliary chemicals (the ones besides CD-4). I feel that whatever I mix with the home equipment I do have would probably lead to more color casts and development problems than going with a production developer from Kodak or Fujifilm.

Judging from the length of the shadows the image in question was taken in late evening. That cast I can see is not magenta but on the red end of the spectrum and this is a natural phenomena with sunlight late in the day. The sky is what ! would expect and is correct, but everything else has the cast given by late evening sun. The developing is OK, it is just in real life your eyes can play tricks and what looks normal, is actually compensated by your brain to look normal.

If you knew the actual degrees Kelvin (Colour temperature) that the sunlight was, you could filter it out before it exposed the film, However if you print your own you can do it at this stage or with scanned negative do the same using something like photoshop.

Bikerider said:

Judging from the length of the shadows the image in question was taken in late evening. That cast I can see is not magenta but on the red end of the spectrum and this is a natural phenomena with sunlight late in the day. The sky is what ! would expect and is correct, but everything else has the cast given by late evening sun. The developing is OK, it is just in real life your eyes can play tricks and what looks normal, is actually compensated by your brain to look normal.

If you knew the actual degrees Kelvin (Colour temperature) that the sunlight was, you could filter it out before it exposed the film, However if you print your own you can do it at this stage or with scanned negative do the same using something like photoshop.

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+1
From looking at your negative sample, they look like correctly developed C41 negs.
If there was a processing problem then the non-image area of the negatives would be affected (the clear orange area)

Lucas Yan said:

The first 10 or so rolls came out great with no color casts. The negatives and scans looked good (on par with lab processed and scanned rolls). However, as I continued developing, I started seeing a magenta cast in the scans and the negatives seemed kind of green. To verify that this wasn't due to a single roll, I ran about 3 rolls, however each resulted in a strong magenta cast in the scans/greenish negatives. Reading PE's old posts, it seemed that I could be underdeveloping with insufficient development of the magenta dye. I had been told by the lab to keep development time the same for each roll and to only increase development time by 10% after the chemicals reached 3 weeks (they're 2.5 weeks old at the moment)

Click to expand...

From this, I understand that you've been using the same 1500ml of developer for 2.5 weeks and for over 10 rolls. That means the developer has been exposed to oxidation significantly, and moreover you're basically dealing with (much) less than 150ml developer per roll. That you're observing gross development problems comes as no surprise, then.

Contrary to what your lab suggests, I would suggest to use your developer one shot, in a rotation tank (for reasons of efficiency; e.g. 150ml for a single roll of 35mm in a Jobo 1510 tank), and store the developer in airtight (glass) bottles. From my experience this gives perfectly consistent results combined with very acceptable economy - remember than the Fuji c41 stuff is basically cheap as chips to begin with, so there's IMO no good reason to try and stretch it beyond what is reasonable.

Please also keep in mind that stuff such as replenishment rates and keeping qualities that you may get from the datasheet or that your local lab tells you are based on a lab environment - your home darkroom is *not* a lab environment! Oxidation rates are likely higher and chemistry turnover times are very likely significantly longer. Fuji may give a replenishment rate of something like 20-35mm per roll for this chemistry, but these kind of figures are in my opinion overly optimistic if you try to transpose them to a small-tank home-development situation.

If you want to run a lab-style replenished developer regime, you can do that at home of course, but in my mind this would only make sense if you consistently run 20+ rolls per week, or 1000+ rolls per year. I assume that's beyond the scale of your current operations...

Long story short: your developer is done because you're expecting miracles from it.

Bikerider said:

Judging from the length of the shadows the image in question was taken in late evening. That cast I can see is not magenta but on the red end of the spectrum and this is a natural phenomena with sunlight late in the day. The sky is what ! would expect and is correct, but everything else has the cast given by late evening sun. The developing is OK, it is just in real life your eyes can play tricks and what looks normal, is actually compensated by your brain to look normal.

If you knew the actual degrees Kelvin (Colour temperature) that the sunlight was, you could filter it out before it exposed the film, However if you print your own you can do it at this stage or with scanned negative do the same using something like photoshop.

Click to expand...

A point of view worthy of respect and study and contemplation.

koraks said:

From this, I understand that you've been using the same 1500ml of developer for 2.5 weeks and for over 10 rolls. That means the developer has been exposed to oxidation significantly, and moreover you're basically dealing with (much) less than 150ml developer per roll. That you're observing gross development problems comes as no surprise, then.

Contrary to what your lab suggests, I would suggest to use your developer one shot, in a rotation tank (for reasons of efficiency; e.g. 150ml for a single roll of 35mm in a Jobo 1510 tank), and store the developer in airtight (glass) bottles. From my experience this gives perfectly consistent results combined with very acceptable economy - remember than the Fuji c41 stuff is basically cheap as chips to begin with, so there's IMO no good reason to try and stretch it beyond what is reasonable.

Please also keep in mind that stuff such as replenishment rates and keeping qualities that you may get from the datasheet or that your local lab tells you are based on a lab environment - your home darkroom is *not* a lab environment! Oxidation rates are likely higher and chemistry turnover times are very likely significantly longer. Fuji may give a replenishment rate of something like 20-35mm per roll for this chemistry, but these kind of figures are in my opinion overly optimistic if you try to transpose them to a small-tank home-development situation.

If you want to run a lab-style replenished developer regime, you can do that at home of course, but in my mind this would only make sense if you consistently run 20+ rolls per week, or 1000+ rolls per year. I assume that's beyond the scale of your current operations...

Long story short: your developer is done because you're expecting miracles from it.

Click to expand...

You said everything I wanted to say.

I followed the advice from this thread and bought some fresh C41 developer from the same lab so I could develop some of the remaining rolls and use the bleach and fixer to capacity. This time around, I one-shotted the developer, and used it up within a week after getting it (I developed 5 rolls with it including Ektar 100, Portra 400, Portra 800, Gold 200, and Kodacolor). The color cast issue seems to have been resolved for the most part, however I'm still getting color issues from Kodak Professional films (Ektar 100, Portra 400, and Portra 800).

As an example, here is a shot from the Portra 400 roll which was I tried doing a straight scan using Silverfast (no color cast correction) as well as a VueScan RAW -> Negative Lab Pro inversion and this is how it turned out:
Silverfast:

Negative Lab Pro


Here is how the negatives for that roll look like:


That Portra 400 roll was developed in the same tank as a Kodacolor 200 roll and the straight scan from the Kodacolor looks fine (no color casts here):


Here are the straight scans from the Ektar 100 roll and Portra 800 roll



While this straight scan from the Gold 200 roll looks good


I'm wondering if there's something wrong with my development process since there is either a red or magenta cast to the Portra and Ektar rolls, or if these color casts are expected from those films and manual color correction during inversion is needed. The Kodacolor and Gold rolls look fine and the Kodacolor roll was developed in the same tank as the Portra 400 one so I'm not sure what's wrong.

It's difficult to judge by digital pictures, but the shot of the negatives on the light table suggests to me at least that the gamma is way too high. I.e. your negatives have far too much contrast. Any color issues would also be exacerbated by this.

Lucas Yan said:

bought some fresh C41 developer

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Was this developer, or developer replenisher? Looking at the results I have a feeling it was the latter and it was used as if it were developer.

Lucas Yan said:

since there is either a red or magenta cast to the Portra and Ektar rolls

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I can't judge that. You've posted scans, and I'm sorry to say this, but scans mean *nothing* to me when it comes to judging color casts or crossover. You never know if you're looking at the film or digital trickery (partly applied 'under the hood' by the scanner software) - usually it's the latter. Just take a look at the two scans of the girl you posted. Same negative, both scans as you say (and I believe you!) without any color corrections...guess what? TOTALLY different results! I'm not saying that scanning isn't useful, or it cannot be used to judge color and gamma. But it ONLY works in a calibrated workflow in the hands of someone who REALLY knows what they're doing (no offense...)

As has been said, I think your issue is primarily due to scanning. Scans are a difficult way to judge the quality and consistency of color negatives, as every scanner, scanning software, inversion technique, and operator introduces many variables that can affect the final product. I avoided color negative film like the plague for several years for virtually identical reasons as you -- I didn't like the way the scans looked (e.g., too contrasty, "color casts," etc.). I've used an Epson flatbed, a Nikon Coolscan, and a drum scanner, plus most of the popular scanning software and inversion plug-ins available, and found them all underwhelming with respect to how they handled color negatives (the drum scanner produced decent results, but can be laborious to work with). And like you, I similarly went through second-guessing my developing technique, first with regard to the use of hobby kits (Arista, Unicolor, etc.), then with respect to Flexicolor chemistry (particularly the bleach and fixing steps). No matter what changes I convinced myself would be the magic bullets to fix things, I could never get the scanned results I wanted.

What eventually changed my opinion on color negative film was switching scanners and scanning software. When I bought a used Imacon Precision II, I was shocked at how good the color negative scans looked straight out of Flexcolor (the software that runs that line of scanners). This included rescans of negatives I had previously hypothesized might have been developed incorrectly. This gave me the confidence to admit that my developing technique had been perfectly fine all along (I even think the hobby kits with blix give perfectly good results, so long as they're used one-shot). Some people don't like Flexcolor, but it's been a total game-changer for me. The color inversion algorithms it employs are really good right out of the box and are much easier and more intuitive to tweak (in my opinion) than anything Vuescan or Silverfast offers.

So to put your mind at ease: I think your negatives are probably developed just fine (though, I'd probably avoid reusing your chemistry so much). An Imacon can be a hefty investment (they currently go for $2,000 and up for a used one), so I wouldn't necessarily advise anyone to rush out and buy one. Depending on how much film you're shooting, paying for lab scans may be a better option. If you want to DIY everything (which I sympathize with), I think the combination of Nikon Coolscan + Vuescan + Negative Lab Pro probably gave me the best results before I switched to the Imacon. The problem I had with NLP is that the preliminary part of the conversion appears to be a black box -- meaning, you can't (I don't think) completely recover everything it does to the image when you hit "Convert". Part of that preliminary conversion is baked in, so if the software initially misinterprets things, there's only so much fixing you can do with the sliders. That can be problematic for high contrast scenes and ones that lack definitive white/gray/black points.

@koraks The lab I got this from told me this was Fuji developer replenisher concentrate with water and Fuji developer starter mixed in (agreed that just developer replenisher and water would probably cause weird results). Is the high gamma due to too much time or too high of a temperature? I tried keeping it to 3:15 and 100-101F but hand development isn’t as accurate as a machine so I could be off by a few seconds or 1F (I usually check the temp of the developer after I pour it out of the tank to make sure it didn’t drop). Is there a better way of figuring out if there are any color casts/crossover? I would like to make sure my development process is decent before running any more rolls.

@Scott J. My scanning setup currently consists of a Coolscan V, VueScan, and Negative Lab Pro. It seems that this setup works really well for consumer rolls, but always off for the professional ones, has this been your experience? I know the Hasselblad Imacon scanners are very good, the cheapest one in my area is selling for $2400 and I don’t think I shoot enough film to justify this. There is someone nearby that has an Imacon scanner and charges $5 per frame so I could have them do a scan of a frame from this roll and check if I’m getting the same issues.

Lucas Yan said:

Is the high gamma due to too much time or too high of a temperature?

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Could be either, or a mixing error (e.g. forgot to add starter, wrong dilution etc.). Or a combination of factors. But like I said, it's hard to tell from digital pictures.

Lucas Yan said:

I could be off by a few seconds or 1F

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Yeah, but that won't have a very dramatic impact.

Lucas Yan said:

Is there a better way of figuring out if there are any color casts/crossover?

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Sure, but they're all rather involved. You'd either have to do color densitometry or use a calibrated scanning workflow (with a reliable calibration target!) I personally do it a 'seat of the pants' way and print negatives optically onto RA4 paper and rely on visual inspection. If the prints are good, the negatives must be good. Conversely, if it's impossible to get a good print in terms of contrast and color balance, there's likely a development issue. This seems similar to scanning and then judging the scans, but keep in mind that when printing onto RA4, there is an absolute reference, i.e. the response of the RA4 paper.

Lucas Yan said:

It seems that this setup works really well for consumer rolls, but always off for the professional ones, has this been your experience?

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Yes, 100%. For example, scanning Ektar, Portra 160, and Portra 400 with essentially the same setup (Nikon LS-50, Vuescan, and NLP) always gave me results that were flat and, in the case of Ektar, plagued with strange spectral peaks in the green and orange bands that made images very muddy. By comparison, when I scanned Colorplus, Gold 200, and Ultramax 400, the results actually looked quite acceptable — good even. A bit grainier, of course, but the colors were more vibrant, more accurate (to my eyes), and the images appeared sharper, likely due to the increased grain.

I think the thing with the pro films is that they’ve been engineered to have lower contrast and to, in a way, mimic the look of digital images. To achieve that, there are some peculiar structural characteristics to these films that make them really sing when scanned well, but that are just beyond the interpretative power of most at-home scanning setups (the scanability of these films was likely engineered with something like a lab-operated Frontier in mind). That said, those same pro films look great when scanned with my Imacon, so their apparent shortcomings must be intrinsic to the specific scanning-inversion chain that utilizes the Nikon scanner and NLP. I think the consumer films are designed to be so middle-of-the-road that they present no problems for a simple setup like the Nikon scanner and NLP.

I think spending $10 or $15 to get a few scans done on the Imacon would be worth it to see if you feel they’re better than what you’re currently getting. If the operator will let you peek over their shoulder, too, that’ll give you an idea of how easy that software is to operate.

@Scott J. I looked at a few other threads and it seems like while the midtones in the color response curve for color negative film are usually linear, the shadows and highlights are not. Since professional films have less latitude than consumer films, it seems like this is what’s causing the shadows and highlights of Portra and Ektar to have a weird color cast. Negative Lab Pro doesn’t have the color correction curves built in and it does a scene analysis instead, Silverfast negafix profiles aren’t very good either.

@Old Gregg Shooting a color passport and scanning it sounds like a good idea. I’ll try that once I mix up the Flexicolor chemicals I just bought. I heard about the Blix issues with consumer kits so the previous set of chemicals I used (the ones used to develop the shots I posted) are official Fuji chemicals with separate bleach and fix.

Old Gregg said:

Kodak invented C41. They are the gods. This means read their Z-131 publication and do everything exactly as it says.

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^^^This, absolutely. My only slight departure from what Old Gregg said would be to add that Kodak also designed C-41 to be pretty tolerant of minor deviations from "perfect". I know from experience that my Jobo pretty much always wavers by at least +/- 0.5 degree C during C-41 development, which exceeds the suggested +/- 0.15 degree guideline published for the Flexicolor chemistry. I've never seen any adverse impact on my film (a control strip might spot a minor difference, but that's simply not crucial to the kind of photography I'm attempting to do). If you're creating photographs for yourself, as opposed to running a lab or some other kind of ISO 9001-certified process, following the guidelines to the best of your human ability will do the job.

If you develop enough color negative film, I'd suggest looking at buying and mixing the chemistry yourself so that you know things are consistent. The Kodak Flexicolor stuff is extremely economical, and the developer replenisher is very shelf-stable if stored in individual, air-tight glass bottles.

@Scott J. I have a 5L kit of Flexicolor LU LORR (starter, part A, B, and C), RA Bleach Replenisher and Starter, Fixer, and Final Rinse. I was thinking of one shotting the developer and final rinse, but was wondering if you reuse the bleach and fixer and if so, at what rates. There are two capacities listed by Kodak, one is for the SM small tank variation of chemicals at 10 rolls of 35mm or 120 per liter of bleach and fixer. The other is for unreplenished minilab chemicals at 6 rolls per liter.

Lucas Yan said:

I was thinking of one shotting the developer and final rinse, but was wondering if you reuse the bleach and fixer and if so, at what rates.

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I one-shot everything. My reason for doing so is multifold: 1) it’s an easy way to ensure consistency (which is why Kodak suggests it for home use); 2) it relieves me of the need to keep track of replenishment; and 3) it allows me to use up the chemicals in a reasonable amount of time (say, 12 months or less). I shoot E6 and black and white more frequently, so I don’t have a huge need for C-41. Five liters is enough to last me about 20-25 developing “sessions” in a 2500-series Jobo tank, and that’s about how much C-41 I do in a year. The chemicals are shelf-stable for longer than that, of course, but rebuying a new batch once a year is, for me, a good compromise on cost and quality.

That said, I’m quite confident you can reliably use the bleach many times over. The main thing is to shake it up and get oxygen into it before using it. I’m considering going to a two-shot approach on the bleach since the RA bleach I buy makes 5.7 liters of working solution (when bleach starter is added), while the RA fixer makes 10 liters of working solution. The two-shot approach on the bleach would allow me to consume the bleach and fixer working solutions at about the same rate.

The non-RA bleach and fixer (which you can order from Unique Photo and elsewhere) are actually a little more economical in terms of liters of working solution per dollar spent, but I prefer the short bleach and fixing times of the RA chemicals (at least 1:00 and 2:00, respectively). I’ve compared the results between the RA and non-RA bleach and fixer, and they’re indistinguishable.

@Old Gregg Thanks, looks like my 5L kit is good for 40 rolls then (8 rolls x 5 liters) if I buy a new set of part A, B, C after I one-shot the first 20 rolls (my Paterson tank takes 500mL per 2 rolls of 35mm).

@Scott J. Didn't know that the bleach and fix times were only 1m and 2m for Flexicolor RA. I was doing 6m 30s each for bleach and fix on the standard Fuji chemicals, so it should save a lot of time.