C-41 processing

[digiconvert]

Hi, just had one of those 'disaster' moments (actual cost about £5 or $8 so no big deal there). I get very stressed developing c-41, I've only done it twice and the temp control etc. worries me. I use Paterson chemistry and for a change read the instructions "preheat for 5 mins" so I placed my water (38deg C) into the tank while my chemicals came up to temp. When I poured this out to add the dev it was coloured- I assumed the dyes had been leached out, AFTER I added the dev this occurred to me !
To cut a long story short I ditched the lot , but I could see the outlines of my prints on the emulsion as I scrapped it. Now I know the sensible thing would have been to see what hapenned but it was a reaction thing, I have some questions.
- Is a prewarm/presoak a good idea ?
- Does the dye get leadched in a soak ?
- Is it ctually worthwhile doing C-41 ? I know of some reputable mail order labs and Jessops have produced good negs when I have had prints from 120, Cost is not on the side of home dev and to make it sensible I think you need to do 2 or more films within a couple of days ( I assume diluted developer has a short shelf life) so speed is not likely to be quicker than lab processing.

I enjoy RA-4 and am beginning to get better at it but the developing is something I am not sure I will ever be comfortable with.

Cheers CJB

 

[Nick Zentena]

Prewarming usually means put the tank into a water bath. NOT putting water into the tank. Warming the tank means the chemicals don't drop in temp when you add them. You could just start out with warmer chemicals.

I was always told to not use a pre-wash with colour but I think PE has mentioned it's okay.

Worth while is a personal choice. If you've got a good quality local shop that does the job then you get to choose. Personally I shoot 35mm and 120. Sometimes I crossprocess. It's a lot easier for me to do a tank then it is to drive to the nearest place that would do everything. It's only stressfull the first few times. Soon enough you'll have trouble staying awake.

 

[jd callow]

- Is a prewarm/presoak a good idea ?

Prewarm the chems Yes (absolutely), I presoak the film for about min @ temp, but many people don't

- Does the dye get leadched in a soak ?

Not to my knowledge, what you are seeing may be an antihalation backing -- I don't know, but the presoak will often be blue or green depending upon the film

- Is it ctually worthwhile doing C-41 ? I know of some reputable mail order labs and Jessops have produced good negs when I have had prints from 120, Cost is not on the side of home dev and to make it sensible I think you need to do 2 or more films within a couple of days ( I assume diluted developer has a short shelf life) so speed is not likely to be quicker than lab processing.

I do my own c41 and it is cheaper than lab or 1hr dev. My chems are in sealed tanks with nitrogen blankets and they last at least a month. I believe in a closed container thay are good for about week.

 

[Photo Engineer]

All films, but particularly color films contain dyes that leach out in a pre-rinse or in development.

These dyes serve a multitude of purposes.

1. Antihalation. These are either on the back of the film or in an undercoat.

2. Acutance. These dyes are in the emulsion and decrease scatter and improve sharpness.

3. Trimmer. These dyes are in the emulsion and adjust speeds to be within an exact tolearance. If an emulsion batch is too fast, then a trimmer dye is added to adjust the speed back to the correct value.

That is what you see. There are more dyes used in color film than in B&W film.

Using a prewet to temper and wet any film is better for uniformity and reduces pinholes (airbells).

PE

 

[pentaxuser]

Hi CJB. In the past I tended to run the film in the Jobo tank while dry over the water bath for about 5 mins before adding the developer at 38C. No real problems that I could see. The alternative if attempting hand agitation would be to place the tank, once loaded, dry into the water bath holding the dev, stop and blix for 5 mins. I never tried a test run with water to see what difference this made to the water temp drop over the 3 mins and 15 sec dev time but the negs looked OK and printed OK.

Last night I tried running the tank with water at 38C for 3mins 15 secs without a pre-warm as if it were developer to see what the temp drop was over that time. I was surprised to see it was about 4 degrees which is quite a lot and means that the dev average temp is quite a bit below the correct temp for much of the time.

I wondered what could be done which didn't involve a film pre-wet or standing the tank with dry film inside over or inside a water bath . I still don't know if a film pre-wet is advisable. I decided to put the empty tank underneath my fan heated print dryer until the tank walls felt quite warm and then add water and try again. The temp drop this time was practically zero.

So a possible solution is to load the tank with film then place under gentle heat until the tank walls feel quite warm and then add developer.

Whichever way you tackle it, the key is to prevent the tank walls from draining heat out of the developer in the form of a heat transfer.

Looking at the negs, I can't say that the above method of dry heat worked any better. It was however faster.

I think the thing to avoid is pouring developer into a tank whose walls are only at room temperature.

As far as economy is concerned, it helps if you have 3-4 films to develop at once. Paterson for one gives times for the re-use of developer for up to 4 films.

IMHO,give it another go. It may not be cheaper but it gives you the satisfaction of saying "I made this" when you examine the negs.

If price was the only consideration then there are probably labs which will produce 36 negs and 36 6x4 prints as cheaply as you can and in a much shorter time but you lose the "I made this" satisfaction. On the few occasions my wife uses film she takes it to the high street lab because she can't wait for me to process the film and maybe take several nights to make 36 prints!

I could never make my living at this game but that's why it's a hobby.

Good luck if you have another go but I am sure you won't need it.

pentaxuser

 

[Nick Zentena]

Last night I tried running the tank with water at 38C for 3mins 15 secs without a pre-warm as if it were developer to see what the temp drop was over that time. I was surprised to see it was about 4 degrees which is quite a lot and means that the dev average temp is quite a bit below the correct temp for much of the time.

I wondered what could be done which didn't involve a film pre-wet or standing the tank with dry film inside over or inside a water bath . I still don't know if a film pre-wet is advisable. I decided to put the empty tank underneath my fan heated print dryer until the tank walls felt quite warm and then add water and try again. The temp drop this time was practically zero.

So a possible solution is to load the tank with film then place under gentle heat until the tank walls feel quite warm and then add developer.

The advantage of putting the tank in the water bath is you already have the waterbath setup and at the right temperture. It's a relatively painless process.

The method you suggest of heating the tank with a hot fan risks over heating the tank. Then you face having the developer go up in temperture.

I mentioned in the previous post but you could just start with warmer developer. If you found adding developer to a room temperture tank leads to a 4degree drop then start with the developer 4 degrees higher. The drop should be repeatable if the tank is always at the same temp. If you store it in a place that gets cold in the winter and hot in the summer then the tank will cool down by different amounts.

 

[Photo Engineer]

Remember this!

If you heat the outside of the tank, by any means, the inside of the tank is not warmed to the same temperature. That is why a pre-wet is so effective. It warms the inside of the tank including the reel(s) and the film.

So, all things considered, a pre-wet is more effective than anything else, and believe me, it is not harmful.

PE

 

[Nick Zentena]

Depends on how long doesn't it? Eventually the whole world comes into balance. A pre-wet will certainly do the job quicker and better. But pre-heating the tank does get things close enough. I think he said adding developer to a room temperture tank dropped it 4degrees if the tank instead of being room temperture was just under C-41 tempertures I bet the temp drop wouldn't be noticed at all.

 

[Photo Engineer]

Depends on how long doesn't it? Eventually the whole world comes into balance. A pre-wet will certainly do the job quicker and better. But pre-heating the tank does get things close enough. I think he said adding developer to a room temperture tank dropped it 4degrees if the tank instead of being room temperture was just under C-41 tempertures I bet the temp drop wouldn't be noticed at all.

Nick; Although I can agree in spirit that everything comes into equillibrium, using a water pre-bath is the most effective. In fact, I use 2 of them, to make sure that the temp is up there.

How do you know when the air temp exchange is right? You don't. Due to the heat transfer with water, equillibration is very fast.

PE

 

[Ed Sukach]

I've just developed a batch of FujiColor C-41 in Tetenal C-41 chemistry. I *do* dry pre-warm ... for about a minute... it is actually the time necessary to pour the chemistry into the JOBO cylinders, wipe out the pervious tank, shake the hell out of the previous cap ... etc. I have read advice by Agfa, Ilford, Tetenal, Photocolor and Russel advising against a "pre-wet" ... but later advice recommends pre-wetting. I don't, and have experienced *no* trouble.

More controversial is whether or not to use a stop bath between color developer and bleach-fix. I've read some strong advice against it, and the Tetenal C-41 instructions do NOT include such a stop bath. Accordingly, I don't use that either.

I've written before that I am convinced that an anally fussy temperature control is simply NOT necessary, and I have seen no reason to change my mind there.

Is it worth it? Yes, as much as the rest of photography is "worth it."

 

[Photo Engineer]

Ed;

A stop bath is not needed with film, but it is needed with paper in rotary processors. This is due to the development rate and emulsion type used in these products.

A fussy temperature is needed for 2 reasons... one is to be able to repeat your results the next time around, and the other is to match speed and curve shapes. These are actually the same things said two different ways.

After all, Fuji and Kodak go to a lot of trouble to make film with the same speed and curve shape time after time. Why mess with it by inaccurate times or temperatures? That is what happens if you are not 'anally fussy' when you process film and paper.

I have done process time, temperature and agitation series in R&D on C41 films. I know what happens if you mess with one or more of them. So, even though your results are good enough for you, they may not be good enough for me.

Retentively yours.

PE

 

[pentaxuser]

Hi all. When I wrote my post I hadn't seen PE's advice that a pre-wet is not only OK but has advantages. It seems to me that a pre-wet for a few minutes at developer temp is probably the best and safest way to go.

It could even be tested at different times until you arrived at the minimum time to obtain a near zero drop in the developer temp. Provided that a pre-wet doesn't carry any risks and it would appear not to, as PE has used it without ill effects, then in both theory and practice it has to distribute the heat within the tank to walls. reel(s) and film more evenly than other methods.

Compared to my method of dry heat and then guessing by feel, it is much more accurate and safer. I admit it certainly wouldn't do to leave a dry tank with film inside for much longer than a few moment with constant checks, whereas PE's method allows one to get a cup of tea or otherwise be diverted without risk.

I am sold unless someone can point to problems that using this method has resulted in.

It's a thread like this and subsequent posts from everyone that makes APUG worth a lot to we subscribers.

Thanks to all

pentaxuser

pentaxuser

 

[Ed Sukach]

THANKS to OLE!!!

His advice - to use butane to displace air over liquid chemistry is the MOST valuable piece of intelligence I've leaned from this accursed machine - anywhere, at any time.

A brief recap:

I had been using Agfa's "Protectan" spray to displace air (with its oxygen) left in the partly-filled bottles containing concentrates of liquid chemistry ... most notably C-41 and RA-4 "kits". Protectan is not now, and for some time, has not been available in the United States.

Ole - our Ole identified the components of Protectan - Propane and Butane. He advised that either would be suitable as a substitute.

I knew that both argon and dry nitrogen would be good ... but the economics of scale came into play - the smallest cylinders of either would be great overkill.
Propane is readily available in much smaller containers - but there is a problem of delivery - one would be forced to use a relatively massive blast - difficult to control - from the run-of-the-mill propane torch.

The solution I've found: A BernzOmatic "Mini Torch", using butane (see attached image - the torch is on the right). Easily controlled (twist ON or OFF) and readily refilled ... small enough to require little space in the darkroom (roll of 120 added for scale) ... and *very* effective. Tetenal C-41 and RA-4 chemistry stored three-fifths full during December 2005, and preserved with a 3-5 second application of butane from this puppy show **no** signs of oxidation, and recently used, yesterday and the day before, work flawlessly.

Once again - a BIG "WAY TO GO", Ole, and profuse thanks.

 

[Ed Sukach]

A stop bath is not needed with film, but it is needed with paper in rotary processors.

My comment was directed toward C-41 processing. I know that it is necessary in RA-4 in ...??? Only rotary processors..? What about trays or tanks?

A fussy temperature is needed for 2 reasons... one is to be able to repeat your results the next time around, and the other is to match speed and curve shapes. These are actually the same things said two different ways.

Uh ... not really. One is "precision"; the other, "accuracy".

After all, Fuji and Kodak go to a lot of trouble to make film with the same speed and curve shape time after time. Why mess with it by inaccurate times or temperatures? That is what happens if you are not 'anally fussy' when you process film and paper.

Ah, grasshopper. I sense that you begin to doubt MY capacity for "anal-retentiveness". I might remind you that, in a a different life, I was a Metrology (not to be confused with "meteorology") Specialist in a Large Well-equipped Lab. My areas of greatest concern were Mechanical Measurements and Calibration, Temperature, Optics, Optical Tooling, Interferometry, Photometer Calibration, Spectrography, Sound and Vibration.... and sundry others. Anally Retention - Retetentivity ... whatever .. was required in my Job Description... but with a footnote: "When appropriate."

One HAD to learn to control the "anal-ness". It would be futile to try to measure a block of wood to one-tenth of a millionth of an inch; In fact it is generally futile to try to measure anything (excepting electronics - I don't know much about those wierdo's) to ONE millionth of an inch.

I have done process time, temperature and agitation series in R&D on C41 films. I know what happens if you mess with one or more of them. So, even though your results are good enough for you, they may not be good enough for me.

Impressive. I respect your judgement over many things here. Uh ... how can I put this ...

*I* (and please realize that I am only directing this towards myself ...) know a little about "really fussy" measurements. However, every day was a new adventure, with new discoveries and surprises. Without cast any light on anyone else ... I came to conclusion that I did NOT 'know it all." Whatever frame of mind anyone else has, is beyond my control, so I do not worry about it.

Seeing that you were so "close" to film R&D ... a couple of questions - I'll use generalities, not something like, "So what would be the effect of setting a JOBO CPP-2 processor incorrectly - say to 37 degrees Celsius instead of the required 38 degrees, and developing Fuji PRO400H in Tetenal C-41? Would it be appropriate to place the noose around my neck and kick the chair out from under me?"

Here goes:

1. What are the temperature tolerances for developing C41 film? Is the perceived Kodak requirement of +/- 1/4 degree fahrenheit really necessary?

2. If it is, how would one go about measuring that temperature, with enough accuracy for control? I know that the best Kodak Laboratory thermometer had a claimed accuracy of +/- 1/4 degree F. For control, one would usually require something on the order of ten times more accuracy ... +/- 0.025 degree F. We had difficulty measuring that accurately with precision thermocouples.

3. What would be necessary to insure that the surrounding media was, in fact, the same temperature as the thermocouple? - or that the temperature of the entire developer was in fact uniform enough, especially considering "agitation"?

Now .. "good enough for me"? Even in the land of ridiculously "close" measurements ... there IS a point when the work is "good enough"... a point where continuing the quest for absolute perfection is just plain "not reasonable".
A GREAT fault is not to recognize this. It was/ is essential that we keep a steady grip over the extent of our capabilities ... and understand just how well we are doing.

This leaves me wondering ... Is MY 'good enough" better, or worse - than YOUR "good enough"...??

And now ... the temperature in my JOBO (good for +/- 0.3 degree Celsius) must be stabilized by now...

 

[Photo Engineer]

My comment was directed toward C-41 processing. I know that it is necessary in RA-4 in ...??? Only rotary processors..? What about trays or tanks?

In trays, with RA4, the use of a stop is optional based on your process uniformity. I use one, but sometimes I don't. At room temp up to 85 deg F, I find no problem, higher temps give more problems and increase the need for a stop.

Uh ... not really. One is "precision"; the other, "accuracy".

Technically yes, but how many readers 'know' this. OTOH repeating your results is getting the same speed and curve shape, but the amount of deviation expressed as a number and the absolute number relate more to precision and accuracy if you want to get right down to it.

Ah, grasshopper. I sense that you begin to doubt MY capacity for "anal-retentiveness". I might remind you that, in a a different life, I was a Metrology (not to be confused with "meteorology") Specialist in a Large Well-equipped Lab. My areas of greatest concern were Mechanical Measurements and Calibration, Temperature, Optics, Optical Tooling, Interferometry, Photometer Calibration, Spectrography, Sound and Vibration.... and sundry others. Anally Retention - Retetentivity ... whatever .. was required in my Job Description... but with a footnote: "When appropriate."

One HAD to learn to control the "anal-ness". It would be futile to try to measure a block of wood to one-tenth of a millionth of an inch; In fact it is generally futile to try to measure anything (excepting electronics - I don't know much about those wierdo's) to ONE millionth of an inch.

Exactly and this is one of those times. Diffusion and reaction rates are often critical, and you get a differential effect as a function of layer in color films that often can completely change color balance or color quality, two different things, BTW.

Impressive. I respect your judgement over many things here. Uh ... how can I put this ...

*I* (and please realize that I am only directing this towards myself ...) know a little about "really fussy" measurements. However, every day was a new adventure, with new discoveries and surprises. Without cast any light on anyone else ... I came to conclusion that I did NOT 'know it all." Whatever frame of mind anyone else has, is beyond my control, so I do not worry about it.

Seeing that you were so "close" to film R&D ... a couple of questions - I'll use generalities, not something like, "So what would be the effect of setting a JOBO CPP-2 processor incorrectly - say to 37 degrees Celsius instead of the required 38 degrees, and developing Fuji PRO400H in Tetenal C-41? Would it be appropriate to place the noose around my neck and kick the chair out from under me?"

Last time I saw Tetnal curves were in the 90s, and that was with EK film, but it looked pretty poor. The curves bowed up in the middle IIRC. At 37 degrees though, you would probably observe about a 10 % loss in cyan layer contrast and a change in the cyan - red axis in terms of color reproduction.

Here goes:

1. What are the temperature tolerances for developing C41 film? Is the perceived Kodak requirement of +/- 1/4 degree fahrenheit really necessary?

No, I feel that 1/2 degree is good enough.

2. If it is, how would one go about measuring that temperature, with enough accuracy for control? I know that the best Kodak Laboratory thermometer had a claimed accuracy of +/- 1/4 degree F. For control, one would usually require something on the order of ten times more accuracy ... +/- 0.025 degree F. We had difficulty measuring that accurately with precision thermocouples.

I use EK thermometers, the old long mercury ones, and double check to 1/2 degree. Over 50 years of my own and photofinishing processing of C41 and C22 I can say that they are all within about 0.1 in color balance on the Yellow -Blue axis. This excepts the old CU Kodacolor which was half tungsten and half daylight balance, and excepts Fuji and Agfa films which tended to wander in color balance.

3. What would be necessary to insure that the surrounding media was, in fact, the same temperature as the thermocouple? - or that the temperature of the entire developer was in fact uniform enough, especially considering "agitation"?

I really don't know. At EK we used steam driven baths with chilled water cooling and recirculation. We also used the large EK mercury thermometers and nitrogen spargers in 3.5 gallon tanks. They were either hard rubber or glass.

Now .. "good enough for me"? Even in the land of ridiculously "close" measurements ... there IS a point when the work is "good enough"... a point where continuing the quest for absolute perfection is just plain "not reasonable".
A GREAT fault is not to recognize this. It was/ is essential that we keep a steady grip over the extent of our capabilities ... and understand just how well we are doing.

This leaves me wondering ... Is MY 'good enough" better, or worse - than YOUR "good enough"...??

And now ... the temperature in my JOBO (good for +/- 0.3 degree Celsius) must be stabilized by now...

Well, as I said, I use 0.5 deg F, and have for over 40 years. I can print negatives from back then and current negatives at just about the same color balance. That is good enough for me. I have contact proofs dating from the 50s up to today and use them to judge prints. I also make my own internegatives and have them balanced such that they print identically to my in-camera original negatives, so I don't have to fuss much with CC filters.

Generally, I can walk into my darkroom and process a roll of C41 color, dry it, and then make a contact proof right off that is just about perfect for exposure and balance. That is good enough for me. I learned that over years of experience and had to perform at EK when I was in the lab. My work relied on being able to reproduce a coating and a process both.

Good luck. Hope your film turned out well.

PE

 

[digiconvert]

The important thing seems to be CONSISTENCY, my thermometer may say 38deg and yours may say 39deg for the same liquid but if I always use 38 and you always use 39 we should both get negatives which match our expected filtration with a given paper.
Is that a reasonable summarry ?

BTW thanks to all for a fascinating and educational response to my post

Cheers CJB

 

[Photo Engineer]

The important thing seems to be CONSISTENCY, my thermometer may say 38deg and yours may say 39deg for the same liquid but if I always use 38 and you always use 39 we should both get negatives which match our expected filtration with a given paper.
Is that a reasonable summarry ?

BTW thanks to all for a fascinating and educational response to my post

Cheers CJB

Yep!

PE

 

[Kirk Keyes]

How do you know when the air temp exchange is right? You don't.

Time to get an adiabatic developing tank!

 

[Ed Sukach]

Gee, guys ... the "nit-picking" crew seems to have fallen asleep on the job.
I wrote about "Agfa Protectan Spray" .... and Protectan wasn't an Agfa product - It was made by Tetenal!

... And no stinging correction? Am I in the right place? Is this APUG?

 

[Photo Engineer]

Gee, guys ... the "nit-picking" crew seems to have fallen asleep on the job.
I wrote about "Agfa Protectan Spray" .... and Protectan wasn't an Agfa product - It was made by Tetenal!

... And no stinging correction? Am I in the right place? Is this APUG?

And after all the effort I put into my last response to you. No comment?

LoL.

PE

 

[Ed Sukach]

And after all the effort I put into my last response to you. No comment?

LoL.

PE

Oh, all right ... if you insist.

First ... "Precision" can also be described as "uniformity of result" .. more or less, stability. Whatever the puppy reads, one gets the same - or closely the same - reading every time. A "precise" temperature reading instrument might read (Celsius) 38.0; 38.2; 38.1. 38.1; 38.0 - when the actual temperature is 37.0. Precision (simplified) is 0.2 degrees. Accuracy error is + 1.0 to +1.2 degrees. Precision also involves time: What is the range of measurement variability over one hour, one week, one year?

Second ... I consider *actual temperature*, while fairly important, to be best left to the winds: I usually sacrifice one frame of each roll of film to the image of a gray card. That image is used to recalibrate the appropriate channel of my ColorStar 3000; and printing proceeds from there. Sundry variables in the process are, in effect, covered by that recalibration. I think that might be a "holistic" approach: Not to worry about the "bits and pieces" of the process when an overall control may be applied to the entire process.

Now that is the way I "do it". I'm not going to browbeat anyone else into the same thing. If someone wants to knock themselves out over each bit and piece - FINE with me. I imagine some might even use crystal balls successfully.

I'll repeat: I have screwed up C-41 developing by having the JOBO set to the RA-4 temperature - 35C instead of 38C. That is 3 degrees Celsius below what it *should be*. Using the "Gray card - ColorStar" deal, I've produced acceptable prints; in fact, I can't really see - or measure any appreciable difference from those from film developed "properly" at 38C.

 

[Photo Engineer]

Ed;

Amazing. We do the same things almost exactly.

I sacrifice one frame to a color chart usually, sometimes 2 (head and tail), but I use 100 F (38C) for both paper and film to save on the chance of error. I use RA RT developer for paper for 45" at 100 F.

My actual temperature is always the same with the same thermometer, and it may not be exactly 100 deg, but it is the same every time, measured the same way in the same place in my Jobo.

Doing things in a set manner is the most important thing in doing good color. I almost wear a rut in the floor when I do things over and over and over.

PE

 

[AgX+hv]

Economical Water Bath

If you want a water bath but can't afford a "real" laboratory model or don't want to build your own, here is way to get a cheap temperature regulated water bath for your chemicals. Laboratory water baths cost hundreds of dollars, but as with many things, it is the marketing, not the cost of construction, that determines what you pay. You can get a "water bath" for $40. I work in a bioscience lab, and because we are a public institution, we don't have big budget. Improvising lab equipment from consumer items happens all the time.

We found that an electric deep fat fryer works great as water bath. There is no law that you have to put oil in it. This is a case where PRIMITIVE IS BETTER. The trick is to get one that operates within the right temperature range and has an analog thermostat (a variable resistor). Digital thermostats might not give you the flexibility you need to fine tune the temperature. Mine has a "warm" setting (about 28C) and the first calibration mark is "200F". Tip: adjust temp with a small amount of water (temperature changes quicker), then add water when you have the right setting. I have maintained temps about 38C easily with this set up.

Another good possibility is an electric fondue (whatever that is) pot. Although I never used one, I think it might be better than a deep fat fryer since it's designed to heat things with lower melting points. Again, primitive is probably better for an improvised water bath.

You're probably better off buying locally, so you can return it easily if it doesn't suit your needs.

R. Chan