Difference between RA4 formula and C41 formula

glbeas · Jan 27, 2008

Just out of curiosity I was wondering what the functional difference between C41 and RA4 chemistry is, besides the obvious fact one is for film and one is for prints. I have a very old box of Ektacolor paper and no RA4 but do have some c41 mixed from a Flexicolor kit and was thinking of playing around with it and seeing how bad it looked. The paper is too old to be worth buying an RA4 kit just to play.

Photo Engineer · Jan 27, 2008

The C41 developer uses CD-4 color developer and contains 'buffer' halides suited to films. The RA chemistry has buffer halides suitable for papers and uses CD-3.

The RA chemistry uses a fairly weak blix, the C-41 uses a very strong bleach and fix. The C-41 uses a stabilzer.

PE

glbeas · Jan 27, 2008

So would CD-4 develop an image on the Ektacolor? I assume I could just dilute the bleach and fix and ignore the stabilizer. What are the buffers for each in general? Would the C41 buffer inhibit the development of the print paper to any degree if I were to add some of the proper buffer?

Photo Engineer · Jan 27, 2008

CD-4 will produce dyes with inferior hue and dye stability with color paper. The paper will develop poorly due to the halide content of the C41 developer. The reverse is also true. The buffers are NaBr, KI and NaCl. They are not interchangable between films and papers.

RA bleach fix cannot be used with film, but film bleach and fix can be used with paper with proper dilution.

But, you are on your own.

PE

glbeas · Jan 27, 2008

Thanks. My main thrust on trying this is getting practice with using the equipment. My darkroom is color capable but to date I've never done more than soup c41 and E6 film. It will be interesting to find out how I need to set up the workflow and how well I can handle the color analyzer, even if it is with inferior materials. When I do get to buy some decent print paper and chemicals at least I will know where some of the problem areas will be.

PHOTOTONE · Jan 27, 2008

RA-4 color print chemistry is probably the most inexpensive of the color chemistries..partly because you only need 2 things...developer and blix, and also the easiest to use. I have found the concentrates (before mixing into working solution) last a very long time. Since everything is liquid concentrates you can sub-divide the chemistry and only make a small amount of working solutions if you wish, and store the bulk of your chemistry in the concentrate form.

glbeas · Jan 27, 2008

Thats good to know. My printing sessions will probably be infrequent due to lack of time. After I do the shakedown of my system I may find I like this!

pentaxuser · Jan 27, 2008

Gary. I am not at all sure that C41 will give you a useful trial run for RA4 although it might be an interesting experiment. It's worth setting up an analyser properly and to do so I think you need the proper chemistry but I'd love to see the results of the experiment just out of curiosity.

pentaxuser

srs5694 · Jan 27, 2008

Just a heads-up: Given all the variables (different paper, different developer, possibly other differences), you'll need to recalibrate your analyzer when you move on to current paper and conventional RA-4 developer. Your proposed experiment may be worthwhile for figuring out a workflow, though. OTOH, it might actually cost more to use your C-41 chemistry than to buy RA-4 for experimentation. (I don't know this for a fact, though, since I've not looked at the costs.) You might want to compare the costs and, if fresh RA-4 is cheaper than the C-41 you've got on hand, add an RA-4 kit to your next order from your photo supplier.

glbeas · Jan 27, 2008

Oh, I'm sure I'll need to recalibrate everything, no doubt. I just want something to play with and this chemistry is mixed and bottled already. Figure I need to use it before it spoils. This is a different direction for me and I want to get a feel for the processes.

glbeas · Feb 4, 2008

Boy that was some screwy looking colors, never really got a neutral tone on anything. I did find out what I needed to know about the workflow, namely theres too much junk in the way.
I'm looking online to order some fresh color paper and developer, and was wondering what the pros and cons are with Ektacolor RA or the RA Prime paper developer. How well do these work with a Jobo system one shot and how would you go about getting best results out of it?
I'm going to get the Ultra Endura paper, the description on that sounds pretty good.

Photo Engineer · Feb 4, 2008

Use RA-RT developer replenisher with no starter.

Use 1' at 100 F or 2' at 68 F. Works wonderfully but with a tiny blue-yellow shift. (about 10y)

PE

glbeas · Feb 4, 2008

Thanks PE! This is going to be fun.
A sour note, the local Atlanta stores don't have any color paper or print developer in stock anymore. You'd think a town this size would have more of a market for something like this.

Photo Engineer · Feb 4, 2008

glbeas said:
Thanks PE! This is going to be fun.
A sour note, the local Atlanta stores don't have any color paper or print developer in stock anymore. You'd think a town this size would have more of a market for something like this.

And, Atlanta is the new Kodak east coast distribution site for analog products!

PE

PHOTOTONE · Feb 5, 2008

The only regional photo stores that are going to have any stock of chemicals or paper are those photo stores in college towns, where the college still teaches an analog photo course schedule. The mini-lab chemical requirements are direct ship to the mini-labs.

Skeptical? Don't take my word for it. If you find a store with a stock of even minimal b/w chemistry and small packs of b/w paper, just ask them if there is a college in town and if that college teaches a darkroom course.

glbeas · Feb 5, 2008

Showcase is just minutes away from Georgia Tech and a branch of the Savannah College of Art and Design and Emory University and a few other places. What happened? I think nobody wants to learn how to do real color prints when it's so easy to put a sheet into a digital printer and push a button.

glbeas · Feb 7, 2008

PE do you have a starting filter recommendation for Ultra Endura with this setup? I have an older dichroic with halogen bulbs.
Thanks for all the help, my supplies are in and I plan on playing in the darkroom over the weekend.

Photo Engineer · Feb 7, 2008

Start with 50M and 50Y with 0 C. The exposure I start with is 12" at about f5.6 - 16 from a negative depending on light box in the enlarger, size of print and size of negative. Usually, 35mm is about the high end and 4x5 is the low end of exposure. Fiddle with f stop and filter pack from there.

PE

glbeas · Feb 7, 2008

Thanks! I wish I could buy you dinner for your help here, it's priceless.

Photo Engineer · Feb 7, 2008

No payment needed. Thanks.

PE

glbeas · Feb 24, 2008

I'm getting results I can live with finally. Takes a bit of learning to judge the filter changes. One thing I'm curious about is the rinse cycle. The final rinse is supposed to be a 1.5 minute rinse. Can this be replaced by several cycles of water in the tube or does it need to be taken out and rinsed in a tray for greatest efficiency and economy of water use?

Photo Engineer · Feb 24, 2008

Gary;

I usually run from 20 - 40 prints per night when printing. I take them out of the drum in pairs or 4s depending on drum after a 1' wash with 4 changes of water. Then I place them in a still tray filled with water at about 80 deg F and let them sit while doing all prints for an evening.

At the end, I take them out of the large tray and wash them in groups of 2 - 4 in a tray of running water for about 2' at 85 deg F. This is about right.

PE

glbeas · Feb 24, 2008

Thanks! Much better that running a full wash one print at a time.

glbeas · Feb 24, 2008

Okay, that worked well. Nother question. I've been using the presoak and optional stop bath with rinse to be sure of no streaking. This has worked well but I wonder if running straight from the developer to the blix stops the development as fast as the stop bath. I see a real saving in time doing that but how prone is it to make streaks or marks using a drum? The one I'm using now is smooth sided and I'm using 40ml a run.

Photo Engineer · Feb 24, 2008

In nearly 30 years of C-41 processing including tank, basked and drum and even using experimental bleaches, I have never ever seen streaks without a stop bath. OTOH, I do see them with paper and need a stop after the RA developer.

PE

Difference between RA4 formula and C41 formula

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