Making some sense of RA-4 Reversal?

[grainyvision]

So I tried RA-4 reversal today to see just how difficult the process appear to be.. Not difficult per se, but a ton of variables to tame to attempt to get a decent result. I tried exposure in 2 ways, under enlarger and exposed in a 120 camera (cut paper down to ~2x2" square) in daylight and tungsten. My initial mix was Dektol 1+2, (2 baths) vinegar based stop bath, and Kodak RA-4 chemicals, all at room temp. I confirmed this mix can get good whites as well as blacks. In-camera I first tried no filtration at 0.8 ISO and it was over exposed and nothing was rendered but cyan. Next tried adding a 60Y filter still at 0.8 ISO. Got a bit more highlight detail, but still nothing but cyan. I can only go up to ~110Y with my filters, and it was clear I needed to really cut a lot of blue... So I went the additive method. Just to give an idea of the relative exposure values. With 60Y I used a 2s exposure. With the lens stopped down by 1, I then used a 1/20 exposure, followed by a 1s green filter exposure, and 4s red filter exposure, using very pure and dark color filters I bought specifically for additive color printing. This resulted in somewhat reasonable colors, though a around a stop too much red. This is of course very cumbersome, but the colors that came out of it were promising. No mottling, good blacks and whites, no real technical problems other than I need to work on color balance a bit more. There's probably some crossing of green shadows into red, but that's not obvious until I can get proper color balance.

On that success, I did some research and came across a thread indicating that someone using Ilford PQ that was "aged" was able to create very accurate colors using something around 20M 50Y under an enlarger. I decided to "age" my mix by putting (into ~400ml) 2.6g of bromide and 1g of sea salt (didn't have any pure non-iodized). I then went back to subtractive filters for testing some enlarging. I ended up somewhere around 60Y and 20M which worked on a standard daylight slide. A darker sunset slide I used around 40Y and 10M. The results on the sunset slide were way too contrasty at first, so I put a "pinch' of sulide into the RA-4 developer. Next print looked great but didn't have great blacks, so I put in a splash more RA-4 developer. This gave me a slight decrease in contrast (though I still would've liked less) and restored the blacks. The sunset slide printed great and was quite true to the raw slide, though it lacked a little bit of red and green saturation and had more clipped shadows. The daylight slide still had some slight blueish-green cast, and it looked like there was some purple shadow color crossing. More importantly, at this point I finally experienced the fabled mottling of solid colors. This was after around 3 hours of test prints, and I only had ~400ml of all chemicals (5x7 trays doing 4x5 prints) so it's very possible this only showed up due to chemical exhaustion, or maybe a bit too much of one of the added chemicals. As a last and final test I took the filter stack for printing and used it for an in-camera exposure. I exposed again at 0.8 ISO (without metering through the filters) of a subject under tungsten lights. The result came out with a thick cyan cast with a slight green cast as well, but it did have some muted reds. The contrast was much more reasonable in-camera than under the enlarger, but the filter stick clearly needed a lot more yellow and a bit more magenta.

Overall I enjoyed the process (especially watching the colors come up in the RA-4 developer) and it was actually slightly easier per-print than normal RA-4 since there was only one tray to move between before I could use lights.

Anyway, it leaves me with a lot of questions though:

* Why does the paper react so differently under an enlarger compared to in-camera? It's significantly higher contrast, and requires a completely different filter stack. The in-camera test of this required a 45s exposure (~1 ISO paper indoors is hard) could the different layers have different reciprocity factors?
* Has anyone else tried this at room temp for all chemicals? I'm sure someone will say "it's not recommended" but I've gotten decent RA-4 prints out of it previously.. With RA-4 reversal I feel like most recommendations are out of the window anyway
* Is first developer in this to-completion? I didn't noticed a lot of difference varying between 1.5m and 3m other than slightly more clipped highlights.
* Has anyone tried this additive exposure method? According to previous research it is theoretically possible to get more color control and saturation through additive printing. Is this kind of control enough to overcome the wonky colors usual with RA-4 reversal? Also is there any reasonable way to meter for additive exposure? I feel like I'm basically just using ratios and guessing at the overall exposure needed
* Could flashing be used to help control the shadow color crossing? (very carefully of course to not ruin blacks)
* Is it normal to be lacking saturation? Is there some way to increase it in RA-4 reversal?
* How would alternative color developers work and produce interesting results? For instance C-41, E-6, or even ECN-2? Paper developers are typically very high activity, but it seems like RA-4 is less active than every other color developer.
* Is there any good way of taming the different color layer development? My understanding is the cyan layer is the "base" speed, magenta is 2x faster, and yellow is 4x faster. Ideally there would be some way of slowing down the fast layers.. I have a few ideas of things that exist as film developers, but no idea how they'd work on paper.

 

[Rudeofus]

* Why does the paper react so differently under an enlarger compared to in-camera? It's significantly higher contrast, and requires a completely different filter stack. The in-camera test of this required a 45s exposure (~1 ISO paper indoors is hard) could the different layers have different reciprocity factors?

No idea which camera you used, but lens flare can be a thing. Also, some lenses have distinct color of their own. Since RA-4 is a very high contrast material, filtration errors show up much more prominently than with C-41 or even E-6.

* Is first developer in this to-completion? I didn't noticed a lot of difference varying between 1.5m and 3m other than slightly more clipped highlights.

Situation is similar to B&W paper: initial density buildup is very fast, then slows down considerably. Leaving B&W paper in developer for two minutes instead of one often makes no difference, but leaving it in there for an hour will give you very dark results.

* Has anyone tried this additive exposure method? According to previous research it is theoretically possible to get more color control and saturation through additive printing. Is this kind of control enough to overcome the wonky colors usual with RA-4 reversal? Also is there any reasonable way to meter for additive exposure? I feel like I'm basically just using ratios and guessing at the overall exposure needed

Neither method will provide you with a decent method for measuring exposures. Exposure measurement in the classical sense assumes that one number correctly represents exposure of three independent color channels, you don't have this here. The only advantage of additive printing is that you already had your special single color filters, and it may be easier to think through the required filter correction.

* Could flashing be used to help control the shadow color crossing? (very carefully of course to not ruin blacks)

Flashing has been used successfully to tame contrast of Ilfochrome prints, so it may work for you, too. It gives you an extra set of variables, which may add to your tool chest or your confusion.

* Is it normal to be lacking saturation? Is there some way to increase it in RA-4 reversal?

Paper manufacturers use special tricks to ramp up saturation, and some of these tricks may wash out with your first developer and are then no longer in place for color development.

* How would alternative color developers work and produce interesting results? For instance C-41, E-6, or even ECN-2? Paper developers are typically very high activity, but it seems like RA-4 is less active than every other color developer.

E-6 CD and ECN-2 CD use the same color developing agent, and E-6 CD is a very active developer. Since you deviate from standard process anyway, you may as well try E-6 CD. Again, it's another variable, which can be a blessing or a curse. Not sure what you would gain from using ECN-2 CD, but you can try it.

* Is there any good way of taming the different color layer development? My understanding is the cyan layer is the "base" speed, magenta is 2x faster, and yellow is 4x faster. Ideally there would be some way of slowing down the fast layers.. I have a few ideas of things that exist as film developers, but no idea how they'd work on paper.

You can create different levels of restraint by adding variable amounts of PMT, BTAZ and Sodium Chloride. The first will mostly stick to the outermost grains, whereas BTAZ and Sodium Chloride will diffuse further inward, Chloride more than BTAZ. This is how color developers are balanced, and it's the reason why RA-4 CD contains both Bromide and Chloride.

 

[bvy]

That's a lot of questions! But good for you for tackling this process. With the somewhat renewed interest in slide film, I think anyone who could master and document a process that works consistently will be a folk hero of sorts in the analog photography community.

First I would suggest you focus on one thing at a time. You're asking about flashing, saturation, in camera versus printing, and a number of other things, and you'll drive yourself batty trying to fix everything at once. I would photograph a target and gray card, and work at trying to get a good print from that one transparency. Then refine.

So I'm the someone who was using the aged PQ, though it wasn't really "aged," more like partially exhausted from regular black and white printing. Well this is hard to reproduce unless you're into wasting lots of fresh paper (and I did that once). Adding the byproducts of regular development to a fresh developer is the preferred approach, but I never nailed the formula. Whatever it is, it will call for adding some combination of potassium bromide and sodium chloride (I think). Basically, I got lucky one time when I grabbed whatever developer I had been using for black and white printing. And I spent a lot of time (and chemicals and paper) trying to reproduce it with mixed, always inconsistent, results. See this thread:
https://www.photrio.com/forum/threa...imulate-partially-exhausted-developer.156555/

To your question, the first development should be to completion, otherwise you're adding another variable. I think I had this issue too, because I was pulling the first development at one minute, but later found I was getting different results for 1.5 and two minutes, indicating (to me) that the partially exhausted developer needed more time to go to completion. Whether that figured into my one-time success, I don't know.

I would also stick to subtractive printing and 94F RA-4 development. There are additive printing kits with diffusers, filters and calculators -- I just bought one but haven't used it yet. If you do hit on success, even partial success, others will be more inclined to pick up where you've left off if you're sticking to mainstream processes.

Good luck.

 

[grainyvision]

What is PMT and BTAZ? I can't find any info for BTAZ. It looks like PMT is 1-phenyl-5-mercaptotetrazole? However, I can't find any source for buying it. It seems like I would basically need to slow down the outer most (blue sensitive) layer significantly in order to have any hopes of using this in-camera without tons of filtration.

The lens I'm using is an f/3.5 Yaschica Mat 124G. It has a coating, but unsure what kind of tint it might impart. I've always loved this camera with both slide and color negative though.

And yes, good point about incorporated agents being washed out potentially in the first developer.. though it seems there is no way around that. The only thing I've seen people say can increase saturation also increases contrast; H2O2 in the color developer.

Unfortunately (probably) don't have any E-6 CD that hasn't gone bad, but I might mix up my most likely ruined half-empty bottles of it and see what happens. I imagine saturation and contrast would be off the charts so it could be interesting for "experimental" looks.

And yes, bvy, that thread is where I got the idea of adding bromide and chloride. You're probably right about focusing on one thing at a time. Personally I think in-camera is really interesting if it can be done in a single exposure, but under an enlarger is of course more useful. I unfortunately have lost my color chart card but I would otherwise be using it. The biggest problem though being that I think reciprocity factor might be playing a part with weird colors on indoors exposure, and typically I don't have time for printing during the day outside of weekends. So, I think doing a single good color chart exposure on slide will be the way I go for enlarger testing.

I would do 94F RA-4, but I don't have any setup big enough for heating the chemical trays. I could potentially heat just the developer, but I'd rather find a room temp process since heating in my darkroom (beyond for film dev) is a real pain. I'd definitely like to stick to subtractive printing if possible since it's so much easier. I don't necessarily like it though. No filter drawer on my enlarger and to get decent yellow filtration for this I need to have like 3+ filters. I've heard of one person creating an LED head conversion kit (I think eventually doing it on kickstarter) which will use RGBU (near-UV leads for high contrast B/W) LEDs for printing. With that type of setup, it'd be easy to do additive printing with a single exposure and with the ability to burn/dodge etc. If I can get one of those I'll revisit additive printing, as I think the additional control might be really useful in this. The biggest problem with additive printing beyond multiple exposures though is it's difficult to translate cast removal to RGB exposure changes.

I can't guarantee "success" but I do intend to at least attempt to do darkroom printing of my many rolls of developed slide film, and if I can tame all the variables, this definitely seems like it could overall be easier than C-41 printing... and in case you've never seen my blog, I'm a big fan of writing up pretty much any discovery I have. Previously I worked on "X-Pro Reversal" (E-6 positive process with B/W and C-41 chemicals) with pretty reasonable success. Come to think of it, the slides I'm printing are from that, though have no visible cast or crossing.. still could be a potential other variable responsible for the color crossing I experienced. Next time I'll check with my actual E-6 developed slides

edit: On the x-pro reversal bit.. I have some C-41 film I developed as positives, ie, orange mask with positive image. I wonder how RA-4 would work for printing that.. Maybe crossed colors + crossed colors == normal colors? Either way, that will definitely be on my list to test out on the next printing run

 

[Anon Ymous]

Since you are US based, Photographer's Formulary used to stock PMT, not sure if they do now. BTAZ is benzotriazole, something they stock.

 

[grainyvision]

Unfortunately PMT is not stocked there anymore it seems. Unsure if it's a substance that requires DEA forms etc, can't really find much info about it

 

[Rudeofus]

What is PMT and BTAZ? I can't find any info for BTAZ. It looks like PMT is 1-phenyl-5-mercaptotetrazole? However, I can't find any source for buying it.

Anon Ymous already mentioned Formulary, here are the links:

1-Phenyl-5-Mercapto-Tetrazole (=PMT. sadly, Formulary uses a strange name, so you only find it when you know what to look for)

Benzo-Triazole (=BTAZ)

It seems like I would basically need to slow down the outer most (blue sensitive) layer significantly in order to have any hopes of using this in-camera without tons of filtration.

Use these restrainers to change the toe, not to substitute for filtration. Adjust the toe such that color cross over is minimized.

I imagine saturation and contrast would be off the charts so it could be interesting for "experimental" looks.

Don't expect too much effect from CD. Contrast is already implied by first developer, and in the case of RA-4 it is mostly predetermined by the paper itself. A commonly used way to lower contrast is Citrazinic Acid. It is used as competitive coupler and works a bit like sulfite. Formulary doesn't list it, but may have it on request. If all else fails: Salicylic Acid is a weak competitive coupler and much easier to obtain.

The biggest advantage of E6 CD is its high activity - color development should run to completion a lot faster than with RA-4 CD.

 

[lantau]

I'm running RA4 at 35°C, but to try this out I'd add a room temperature tray of b/w paper developer.

How long is the paper iluminated for reversal? I noticed that RA4 paper is printing out pretty quickly. I assume that is to be strictly avoided?`

 

[grainyvision]

I'm running RA4 at 35°C, but to try this out I'd add a room temperature tray of b/w paper developer.

How long is the paper iluminated for reversal? I noticed that RA4 paper is printing out pretty quickly. I assume that is to be strictly avoided?`

I don't get any printing out after several minutes under room lights. I do 30s minimum

 

[grainyvision]

So the experiment using positive processed C-41 film with this worked great. The weird color crossing of the paper actually seemed to correct a few of the weird color crossings with the C-41 film. Also due to the orange mask, a level of yellow filtering I could reach was possible (probably 90Y at the most with Kodak Gold 400) I was able to get a really good (but somewhat mottled) middle grey. Contrast is really extreme though, despite how low contrast the C-41 film tends to be. A lot of clipped highlights and blocked shadows. Saturation seemed to be on-par with the corrected scans I have also. I did a test print with skin tones, and though it came out a bit golden/orange, it is true to how the C-41 film renders the image, but with much higher contrast. I think using a medium or low contrast first developer on the C-41 film would probably bring the film into the contrast range of the paper. I only did tests with Kodak Gold 400. I plan on printing the significantly more color crossed Superia 400 next to see how it will render in this.

Observations in this run:

* Dektol 1+2 and 1+3 are pretty much the exact same in this process as a first developer
* A bit of bromide and chloride in the first developer seems to help slightly with contrast and mottling without changing color balance response significantly
* For some reason, the instant RA-4 paper goes into Dektol (under room lights), the paper's blueish coating will instantly vanish. When put into RA-4 developer however, the coating seems to stick for 15s or more, until most of the color starts to come up. Is this a potential cause of the mottling? Maybe Dektol is way too basic for the paper? The mottle effect seems to happen solely in the first developer, and in my instance I can see it in the mid tones when it's still a B/W negative.
* Fearing of incorporated developers or something (common cause of mottle in lith printing), I tried rinsing the paper before first development. This seemed to have no effect.
* It seems like the best color balance can somewhat vary depending on exposure, with lower exposure values tilting toward blue.

Some pictures attached

Corrected scan of color chart exposure


Uncorrected scan (daylight lit, 5900K color balance)


Cell phone pic of print (80Y, 50M)


Some of the prints I made (top color chart is with no filtration)

 

[grainyvision]

So I had an interesting thing happen last night with my RA-4 reversal testing. I tried just (without any B/W processing, just some room light cut RA-4 strips) sticking a strip of paper into some C-41 developer I had laying around. It had the most strange behavior. First, only blues came up, which isn't really too different to RA-4 developer in room lights, but it was very very slow.. like it got to maybe a 20% blueish grey. I figured the C-41 was either bad, or wasn't active enough to do the paper. Started rinsing the test strip, and it instantly got 2 or 3 stops darker, but then stopped after so much rinsing. Then for fun, put it back into the C-41 dev, again nothing seemed to happen, it was still a dark purpleish grey, got maybe a tiny bit darker and figured that must be it, C-41 won't take it any further.. rinsed again and somehow it got darker, yet again. I even tried adding some water to the C-41 dev, thinking maybe the C-41 is too concentrated (how!?) but the same effect continued to happen. Really weird. anyone have any ideas how that's possible?

More sadly though, I tried several candidate B/W developers (DD-X, Dektol, Ilford Warmtone, weak and strong lith developer) in my cabinet, and a number of additives to each (photoflo, sulfite, bromide, citric acid, chloride, lith developer parts A or B), but all produced noticeable mottle on strips of RA-4. There is some potential to avoid the mottling by incomplete development, but that complicates things significantly and I'm not sure I can achieve pure whites doing that. There definitely seemed to be a max density grey that each developer settled at, and then quickly began to mottle. I tried DD-X 1+9, but after 4 minutes of agitation the paper still only had a very mild grey density. With the addition of base (lith part B) it sped up, but still had very weak density compared to stuff like Dektol. The addition of extreme amounts of bromide and chloride to Dektol, the paper took on an interesting orange look, but was considerably more mottled than with normal Dektol. Lith developer was extremely slow, even with addition of old brown and plenty of each component. I wasn't patient enough to see how much density it'd have in total, but after 10 minutes it was still a very mild grey.

The major interesting difference between how the paper immediately responds in proper RA-4 rather than B/W, the blue coating does not dissolve quickly. In proper RA-4 it's unclear exactly when it fades, as it seems to stick on until it's too dark to see if it comes off. The coating dissolves in sodium hydroxide base, but I'm unsure if every base will remove it. It mostly unaffected by water. Even in the C-41 developer (shares many properties of RA-4) the blue coating came off within seconds of putting it in. It seems to slow down with addition of acid to the developer, but also typically with an (expected) massive decrease in activity. I'm not sure what the blue coating actually is. It doesn't seem to be any incorporated developer as it does not stain with strong base (unless you give it ~45 minutes) I'm curious if it's removal is responsible for the mottle. I thought maybe that indicates the developer is too basic, but even with developers quite weakened by acid, including unbuffered weak lith developer. Several developers I used are also known to be less basic than RA-4 developer. There must be some other mechanism by which it is not removed in RA-4.

I'm curious now if it might be possible to quickly do B/W development, but that also gives enough leeway to allow removal before the mottle forms. It seems that overly long development, like Dektol 1+10, the mottle appears earlier in the process before it actually hits maximum density

 

[Rudeofus]

I am not an expert in RA-4 processing by any stretch, but here are my thoughts: RA-4 was and is one of the largest scale color processes out there. Great effort was invested in optimizing every bit and piece about RA-4 paper, and this specifically applies to its silver content. Therefore I am not at all surprised, if RA-4 does all kinds of really weird stuff if your process deviates strongly from standard RA-4. Obviously standard B&W developers will not get much density, because the silver content is so extremely low.

What you observed is the result of a pile of unknown (to us) compounds in RA-4 paper, which serve the sole purpose of getting a decent image at the absolute minimum cost possible.