Test of Anscochrome processed as color positive

[grainyvision]

So I did some searching beforehand on photrio and basically only found questions of "if this possible" and "it was a proprietary process, it won't work"... Well I decided to try it anyway. The Anscochrome I have is probably some of the best kept stuff in the world. I bought a lot of expired film from an estate sale. Tons of different stuff including ansocchrome in a variety of formats. The person who I bought the film from told me he found it in the guy's fridge. Comparing it to the other B/W films, this definitely appears to be the case. So it's all "good" condition but not perfect. It doesn't appear it was all frozen, just kept cold and temperature controlled.

So I did a few preliminary tests on Anscochrome and found that the biggest caution is that the emulsion is extremely soft, especially when wet. Even when dry it can be deformed a bit by pushing on the film pretty hard. I also tested that it responded to C-41 developer by simply putting a strip of the 35mm in room temp C-41 for a few minutes followed by bleach and fix. C-41 will develop color on the film. Total stock is a few rolls of 35mm in 500 ASA, 1 35mm roll of duplicating film, 1 4x5 pack fo printon direct positive paper, 2 4x5 daylight films, 2 (1 opened) tungsten films. All films had an expiration date of between 1963-1967. The preopened tungsten is what I started with. The package doesn't actually have any speed or real directions other than saying that it needs a filter. The specific pack I used said it needed 05M. I ended up doing some research and found of all things a military photography document about the processing instructions and speed of these 4x5 sheet films. The daylight film is 32 ASA (reduced to 8 ASA under tungsten with filter) and the tungsten film is 25 ASA (20 ASA under daylight with filter). The processing time required is... intense. Temperature is to be 68F +/- 0.5F, throughout the entire process. Basic summary:

* First developer - 14m
* Stop
* Harden
* Wash
* Re-expose - 1m per side
* Color developer - 14m
* Harden
* Stop
* Wash
* Bleach - 5m
* Wash
* Fix - 4m
* Wash
* Final Rinse

The process was proprietary and in my searching I've not found any info at all about the process other than that it existed and these processing instructions. I couldn't find what color developing agent it used, potential agents of the first developer... anything. But I have a lot of film that is otherwise useless to me... So, I did a thing.

I shot 2 sheets of the tungsten film as a long-exposure under tungsten lights. One was shot at 25 ISO using a 30s exposure time, the other was with 1/4 of the film shot at ~50 ISO for 15s and the other portion of the film shot at 12 ISO for 60s. I also ignored the filter recommendation

Processing temperature was 70F (room temp) and all washing done with cold water from my tap (~60F). I used a spearman 4x5 developing tank and did agitation every 1 minute. My process was as follows:

* First developer - custom dilution of HC-110, 30ml of concentrate to 700ml of water - 13m
* Wash/water stop
* Re-expose, 1 minute per side (this emulsion strangely seems double sided!?)
* Color developer - Normal Kodak C-41 LORR working solution developer - 15m
* Wash/water stop
* Bleach - Fujihut C-41 bleach - 7m
* Wash
* Fix - Fujihut C-41 fix - 7m
* Wash

Amazingly, the results are proper kinda usable (with correction) color! The emulsion is marred some on the edges and is extremely fragile through every step of the process. Definitely only handle by edges and if you're really worried, don't have any of the important part of the image on the edges when taking a picture. The spearman tank system actually scratched the edges of the film due to how soft the emulsion is.

There is a very strong cyan shadow cast, but otherwise a visible representation of all colors. The results were fairly low contrast for slide film, but if I'm only developing this film to scan it, then what does that matter. I believe the cyan cast is primarily due to age fogging. During re-exposure, one side of the film was quite dark with fog and the other side seemed to have little or no fog. There was no eye-visible grain and red and green seems to be rather balanced despite the cyan cast. Because of the low contrast, both exposure levels produced decently usable results. The 50 ISO exposure didn't really cover enough of the subject to tell, but the 12 ISO shot looked to be the best. Whites also appeared to properly go to clear at 12 ISO with maybe a bit of cyan cast. A heavily fogged (I messed up loading the holder) sheet was also developed and came out with a very slight orange cast on the clear film.

Overall, the results are definitely exciting, even if most of the surviving film out there would be insane to process as reversal due to sub-par storage. I don't have a good proper way of scanning LF film so that's the primary reason I went with reversal. This film would likely produce reasonable and easier to correct results in C-41 negative developer, when done at low temperatures.

Attached pictures are a simple phone photo of the backside of the film during re-exposure (front side was too dark to really get a good picture of). The other picture is the final 12 ISO image on a daylight backlight

 

[foc]

Very interesting and well done.
I found this in my BJP 1974 and hopefully it might help.



Looking forward to seeing more of your results.

 

[grainyvision]

Very interesting and well done.
I found this in my BJP 1974 and hopefully it might help.

View attachment 245161 View attachment 245162

Looking forward to seeing more of your results.

I wonder what is "old" GAF/Ansco and what is "new". A processing temp of 80F seems completely impossible for this film, the emulsion is extremely soft even with the cold 60F washes and tests with ~90F water resulted in the emulsion lifting. I suspect that these sheets would be considered "old" and maybe required different processing than the "new" stuff referenced here. Manufacture date was likely no later than 1961 or so. In some searching I also found a similar first developer formula though with a developing temp of 68F and time of 12m. I'm not sure why there is so much variance in the timing. In addition the color developer used, according to the late PE, was a "derivative" of CD-4, which probably explains why CD-4 in C-41 works decently for it. According to the post I found somewhere here, the agent used in the color developer for Ansco was less active than CD-4. In slide film I think the color developer is a lot more flexible though, since it's mostly developed to completion.

I believe the method of reducing the cyan cast is to work out a way to reduce the fogging in the film. The top layer, (probably forms yellow) appears to be the most fogged with the bottom (probably forms magenta) is the least fogged. I think next time I try this process I'll shoot 1 and 2 stops over exposed, and use HC-110 dilution A. I'll also try adding some restrainers. I'm thinking the following:

* 0.2g bromide
* 10ml of 0.2% benzotriazole

I'll also use a processing time of just 12 or maybe 10m and keep pretty much everything else the same. I don't expect I have nearly enough film to really figure out a picture perfect way to process it, but I would really like to calm down the cyan cast a bit. It's otherwise really fun to experiment with color film in 4x5 since modern 4x5 color film is so expensive. ~$50/10 sheets typically. When I eventually shoot the 35mm film I have of this format I'll process it at C-41 negative at room temp, since I can easily scan and color correct smaller format film. I expect a 500 ISO film stored for 60 years in even in ideal conditions will be absolute toast though

edit: The big thing missing from HC-110 that would be present in the actual formulas is thiocyanate. However, thiocyanate increases speed and fogging levels of the top layer, likely making the cyan cast much worse. It would likely cause the highlights to clear out and increase overall contrast significantly, but I think it'd be a bad idea to add for a film of this condition

 

[grainyvision]

A few minutes in photoshop with a cropped scan (I can only scan ~1/2 of a 4x5 sheet in my DSLR setup) gave me this after correcting out the heavy cyan cast. Really not bad, but lacking quite a bit in saturation

 

[Donald Qualls]

This cast may be a result of modern developer (based on CD-4) being used on films that expected an older developing agent (seems to me CD-2 was used in C-22 and possibly in E-3, both of which would probably have been the "new" stuff in the early to mid 1960s). But I think it's very reasonable that age fog is a significant part of it. Could you preflash the film with yellow light, perhaps, to color balance the fog?

 

[grainyvision]

Given that the cast is actually visible in the B/W reversal development (ie, one side is very dark, other side is much lighter) I'm going to blame 90% of the cast on age fog and incorrect first developer formulation.

I did a new test run, primarily just tweaking the first developer. I wanted to effectively "pull" the film to maybe develop less fog, as well as use some additives like benzotriazole.

First developer formula:

* 30ml HC-110 concentrate (~A concentration)
* 0.4ml of 0.05% iodide
* 0.5g potassium bromide
* 2ml of 1% benzotriazole in 70:30 water/isopropyl alcohol
* 0.2g sodium thiocyanate
* top to 500ml with water. developing temperature ~69F, 10 minutes

The results are significantly improved, but as expected still quite far from perfect though. The highlights more properly cleared, and instead of a straight up cyan cast to the blacks, it is now a somewhat darker teal cast. Overall color balance is still cyan tilted, but to a significantly reduced extent. There is now some green cast there as well. Contrast is still sub-par, though that makes it have more exposure latitude so I'm not as concerned there.

More exciting than the film though is the results I got from some "Printon" Asncochrome direct color positive printing paper. I could find no info at all about speed, so I just took a guess and shot a sheet at 8 ISO and 4 ISO. The 4 ISO is definitely better but really needs another half stop or so. The results though are incredible. Proper clean whites, proper very dark blacks, mostly correct color balance with just a not too bad blue cast and very good color saturation. I didn't use any filtration and the filtration recommended on the box was 15M 15Y. The paper is also recommended for use at 3000K, rather than the standard tungsten 3200K. I think with the proper filtration this would actually give proper usable results at 3 ISO. The only color crossing I can see beyond the blue cast is a slight tilt to green in the dark shadows and greens in general being much less saturated than red or blue.

Results attached of the tungsten film shot at 8 ISO (with original run at the bottom for reference) and the paper shot at 4 ISO. Both using tungsten lights as long exposures and no filtration

edit: Also I believe that Anscochrome's color developer is closer to CD-4 than to CD-2. At least according to an old thread I found talking about similar non-American color developers. Apparently the agent used is a lower activity derivative of CD-4. So I believe that CD-4 is probably the best bet using modern available chemicals

 

[grainyvision]

I tried this again using an approximation of the original first developer. Specifically I halved the amount of thiocyanate, increased iodide by 25%, substituted the metaborate with carbonate and borax, and substituted the antifog with benzotriazole. I know it's quite a bit of modification, but didn't want to order new stuff just for this or worry about how to designed a developer for this. The results were significantly worse than with HC-110. The thiocyanate especially brings out the fog level making the slides quite poor.

I also ended up mixing the bleach from the formula except for excluding the boric acid, acetate, and pot alum. I don't have any of those and really don't feel like it's a great idea to try to substitute them with my limited knowledge since acid+ferricyanide is something that requires caution. I tried redipping some of the previous slides in the bleach and this bleach definitely works better. It increased density slightly and added considerable more green to the very cyan casted slides. Far from usable, but an improvement.

However, I've had enough of wasting this precious film, so I decided to instead just do a straight up C-41 cross process as negative, but at room temp due to the super soft emulsion. Exact process:

* All at a room temp of ~70F with tap water temp of ~66F
* Pre-rinse for 2m (gives up a lot of blue dye)
* C-41 developer, 5m. Agitate 30s initially, then 30s per minute
* Rinse for 2m
* Custom ferri bleach, 5m
* Rinse for 4m (the bleach is pretty slow to rinse out, I still got yellow rinse water after 2m of rinsing)
* C-41 fix, 5m
* Rinse

I also over exposed for 1 and 2 stops (2 stop negative not shown). The results overall look under developed but still very good for a 1960s expiration color film cross processed using a process that didn't even exist at the time. Strikingly it looks exactly like a C-41 negative! I'm unsure how fogged the film truly is, but fog levels seem minimal here if the "mask" is an actual mask and not fog. The base is specifically an orange-ish magenta. Grey density is orange casted like a C-41 negative. All colors are represented. I don't have a good way of scanning 4x5 but will try to figure out something better than this makeshift job. Manual correction from a cell phone "scan" indicates there is definitely looking to be quite usable. Middle grey is a little bit blue, but this was taken under cloud cover so not too unexpected. Color vibrance otherwise looks pretty reasonable. The real test would be to try printing this to RA-4, but I'm happy enough if it scans well. The 2 stop test didn't include a color chart so hard to judge, but does seem this has a strong tendency to go blue in shadows. Either way, very excited to figure out a more proper way to scan this!

 

[grainyvision]

More properly scanned and processed images. Turned out very grainy! Even with 16MP scan resolution the grain can easily be resolved. The first image was stitched and the weird edge colors are due to scanning artifacts

 

[foc]

Great results, thanks for sharing.
The photo of the orange/magenta mask reminds me of the old Agfa CNS negs.

 

[Mike1A]

Earl:

Hey, I'm a bit of a newbie here but I've been lurking for years. I'm working with some of the same stuff as well as some old Eastern bloc/soviet film which is very similar I'm sure

The soft emulsion has kicked my butt more than once. I will always use a hardener either prehardener or hardening bleach from now on. What you want is a copy of:
"How to Process Ansco Color Film" 1948 by Lars Moen published by Ver Halen Publications. It has some formulae although not the original formulae they are pretty close.

A very good reference which is available online and includes the 1st developer, color developer and other bath formulae is
“Processing Control Procedures for Ansco Color Film* By J. E. Bates and I. V. Runyan Ansco, Binghamton, New York
That article states that to compensate for the blue cast increase the iodide and increase the development time. The 0.01gm of potassium iodide (yes 100th of a gram, I believe) as stated in FOC's post from the BJP pages, can help mitigate the blue. During color development rather than in the first developer. According to the article you can't correct those casts in the first developer since you are trying to get to the lower layers of the emulsion with the color developer - that'[s the purpose of the iodide and the slightly longer dev times. Maybe drop your .4ml of 0.05% iodide to .2ml in the color developer. A little goes a long way. I always use iodide in these older film developers but i never adjust it. Also if you use potassium ferricyanide bleach, make sure there is a good wash after the stop and after the bleach to help prevent more blue cast.

I don't believe the Ansco developers were that close to the Kodak CD series, although I usually use CD-2 because it is a pretty strong developer...

Hope that helps.

Mike

I hope that is helpful. Looks like you

 

[Mike1A]

Specifically I halved the amount of thiocyanate, increased iodide by 25%,

Decreasing the thiocyanate in the first developer will probably INCREASE the blue cast in reversal. You might try just increasing the thiocyanate first in the 1st dev and see if that mitigates at all.

I think the shots are great. Color is always a miracle and yours is not too bad. I would say increase exposure but youre out there already. Maybe increase the color development time. Originally those were between 8 and 14 minutes.

Hope that helps.

Mike

 

[Rudeofus]

@foc posted two sets of formulas. Color developer C15 from the first formula contains "Diethyl paraphenylenediamine sulphate", which is CD-1. The GAF 64 process uses "N-ethyl N-(ß-oxyethyl) paraphenylenediamine sulphate", which is called T-32 or CD-32 and does not exactly match any of Kodak's color developers. There is an important difference between CD-1 and CD-2, and it is the same difference as between CD-4 and T-32: there is an extra methyl group in the 2 position of CD-2 and CD-4. PE once reported, that this extra methyl group twists the final dye molecule, and this geometric difference prevents attacks by aerial Oxygen. There may be a slight dye hue difference between T-32 and CD-4, but your CD-4 processed slides may actually last longer.

PE also recommended a hardening prebath for soft emulsions, the formula must float around here somewhere. Hardening is also the motivation behind adding Potassium Alum to the Ferricyanide bleach. Potassium Alum is very easy to get in pharmacies and probably some hardware stores, and I highly recommend you add it to your "custom bleach". If you do this, then you should also add the Boric Acid or Borax (both should be very easy to get - and cheap), since for whatever reason Aluminum ions stay in solution better if Borate ions are present.

@earlz : think about adding filters during exposure instead of messing with the first developer. This film is 50+ years old, it's well possible, that the cyan-layer has lost more sensitivity than magenta or yellow. If you allow stronger exposure in the red sensitive channel, you may be able to get better images. BTW these already look pretty good, I've got much worse from fresh E-6 film with my first few homebrew concoctions.

 

[Mike1A]

A simple hardening bath is:

Potassium Alum 30g
Water 1000ml

You can substitute Chrome Alum at the same rate. This is actually Ansco Hardener 901.

I think this is the same that PE cited numerous times when trying to avoid Formalin.

ORWOCOLOR 37 Stop, which should be hardening is:
Sodium acetate15g
Acetic acid, glacial 25.00 ml
Water to 1000ml
pH - 4.0-4.4

I have yet to try a hardening bleach but I have seen a few, this is supposedly Ansco Hardening Bleach 715A:
Water 750ML
Hexametaphosphate (Calgon) 0.5g
Potassium Ferricyanide 100g
Sodium Acetate (Anhy) 40g
Acetic Acid (glacial) 2.25ml (To adjust pH)
Water to 1L
Adjust pH to 4.5-4.7

Another hardening bleach is on @foc second page above (187) from BJP which is the Ferrania VC212 bleach on the lower left part of the page.

BJP 1964 also lists an interesting Gevacolor reversal bleach hardener:
Sodium Acetate 30g
Potassium Alum 30g
Borax 10g
Potassium Ferricyanide 30g
Potassium Bromide 15g
water to 1000ml
Unfortunately I don't see a pH reference. Interesting that PF level is 1/3 but with the addition of the other potassium elements.

There is another Ansco hardening reversal bleach but it includes Pot Ferricyanide and Pot Ferrocyanide but the 715A above seems to be the simplest of what I've seen.

Jacobsens do a great job in describing the variations of color developers in their "Developing" book (downloadable at various spots). The best that does for me is tell me which ones are synonymous since I can't make heads nor tails of the color developer names. I use CD-2 to replace most of those since it is so active. I have some PPD sitting on my shelf that I might also try. But use what you have. Somewhere is PE's chart on substitutions between kodak CDs. I'm sure it pained him to do that since he was very sensitive to the technical differences between emulsions and developing agents, but thankfully he did that anyway. As @Rudeofus states the East European CD agents and the Kodak agents differ, and the use of the name "CD-x" outside of Kodak does not indicate the agents are similar. I think someone could write a book on color developing agents with a chapter on their various chemical names and I would still be confused.

Luckily at least 80% of the fun for me is trying and failing.

Hope that helps,

Mike

 

[Mike1A]

And yes, again as @Rudeofus says we cannot ignore the age of the film. My very limited experience with Ansco emulsions is that they are less robust over time. I love Agfa and Ansco colors and in some ways they seem more fleeting. I have had some failure of older Ansco B&W emulsions where contemporaneous Kodak emulsions held better. Of course I have no way of knowing how those were stored or handled either.

I've said before elsewhere that I think the miracle of photography is beautiful even when it fails.

 

[Rudeofus]

I have yet to try a hardening bleach but I have seen a few, this is supposedly Ansco Hardening Bleach 715A:

The bleach is listed in Glafkides on page 618, and it is not listed as hardening bleach. The same page contains a hardening fixer, which unlike the bleach does contain hardening agents. Interestingly this bleach only contains Acetate counter anion, there is no other suitable anion in this bleach. I also have no idea, what the Calgon is in there for at this low pH.

Another hardening bleach is on @foc second page above (187) from BJP which is the Ferrania VC212 bleach on the lower left part of the page

The thing I find most interesting about this hardening bleach is its high pH. I was supposedly the great breakthrough of Kodak's F-5 fixer, that with the help of borate ion it could raise hardening fixer pH up to 4.8 without triggering precipitation of Aluminum Hydroxide. This bleach also uses borate, but raises pH to 5.1-5.2.

BJP 1964 also lists an interesting Gevacolor reversal bleach hardener:
[...]
Unfortunately I don't see a pH reference. Interesting that PF level is 1/3 but with the addition of the other potassium elements.

I'd keep pH at or below 4.8 (see my Kodak F-5 comments) above.

As @Rudeofus states the East European CD agents and the Kodak agents differ, and the use of the name "CD-x" outside of Kodak does not indicate the agents are similar. I think someone could write a book on color developing agents with a chapter on their various chemical names and I would still be confused.

I have seen some different counter anions to color developing agents, like the chloride and sulphate salts of N,N-Diethyl-p-Phenylenediamine both called CD-1, but regardless of recipe origin you should get the same color development agent for anything called CD-x. Kodak published CD-1, CD-2, CD-3, CD-4 and CD-6, the CD-32 name is AFAIK not from Kodak. There is a well stocked list of chemical trade names here in the article section.

 

[Mike1A]

The bleach is listed in Glafkides on page 618, and it is not listed as hardening bleach. The same page contains a hardening fixer, which unlike the bleach does contain hardening agents. Interestingly this bleach only contains Acetate counter anion, there is no other suitable anion in this bleach. I also have no idea, what the Calgon is in there for at this low pH.

The thing I find most interesting about this hardening bleach is its high pH. I was supposedly the great breakthrough of Kodak's F-5 fixer, that with the help of borate ion it could raise hardening fixer pH up to 4.8 without triggering precipitation of Aluminum Hydroxide. This bleach also uses borate, but raises pH to 5.1-5.2.

I'd keep pH at or below 4.8 (see my Kodak F-5 comments) above.

I have seen some different counter anions to color developing agents, like the chloride and sulphate salts of N,N-Diethyl-p-Phenylenediamine both called CD-1, but regardless of recipe origin you should get the same color development agent for anything called CD-x. Kodak published CD-1, CD-2, CD-3, CD-4 and CD-6, the CD-32 name is AFAIK not from Kodak. There is a well stocked list of chemical trade names here in the article section.

______________

Well, that is interesting. I had always assumed the sodium acetate was a hardening agent, but I guess it is just a buffer or to control the pH? I went back into the references, one of which was stolen straight from Glafkides and the only real references to hardening are those with Pot/Chrome Alum, whether or not they also include the acetate. Thanks, I stand corrected on that. As I said, I've only ever used alum. However I WANT to try a bleach hardener for the eastern european films as well as C22 and E-3 / E-4 films. So the VC212.

That correction should also be noted about the stop bath above - ORWOColor 37 which, by the same chemistry/logic would not necessarily be hardening.
Rather Jacobsons, repeat what they say is BJP 1971 VC233 stop/hardener? (p377 in the '72 edition):

VC233:
Sodium acetate 50g
Potassium Alum 30g
Sodium/Potassium bisulphATE 30g
Potassium Metabisulfite 5g
water to 1000ml
pH 4.0 - 4.5

ANSCO is listed next to that as:
Sodium Acetate 20g
Potassium Alum 10g
Sodium/Potassium BisulphATE 12g
Boric Acid 3g
Water to 1000ml
pH 4.0 - 4.4

They list Chrome Alum hardener (30g to 1000ml water) as pH 3.3-3.7 I don't think I ever noticed the pH of the hardener before.

I also had not paid close attention to the pH differences between ANSCO and Kodak. Kodak Ektachrome bleaches are more base than the ANSCO bleaches which Glafkides notes. And then browsing Jacobse\ons again, interesting to see side by side Kodak E-3/E-4 fixers at pH 4.4-4.9 vs ANSCO at 9.3-9.7.

I have had eastern bloc emulsions fall apart after bleach and after fix and I don't think I paid as much attention to the management of pH differences across the process. I did create an AGFA bleach specifically for pH, at one point, but I could do with going back and just designing the start to finish process for AGFA/ANSCO/ORWO instead of mixing in kodak recipies because they are available. (That is probably more admission than I would want to make, but it is true and, I think, important to state).

Mike

 

[Mike1A]

I'd keep pH at or below 4.8 (see my Kodak F-5 comments) above.

I would agree for the Agfa/Ansco emulsions. Kodak bleaches are between 6.5 - 7.0 that I have seen. Jacobsons show 6.6-7.0 in the 72 edition, I'm sure that is from BJP but I don't have it. 25g of potassium nitrate will probably do to hold that pH. Jacobsons state that for AGFA CNS films the bleach pH is critical for cyan layer mask formations, while for kodak and 3m these occur in development. Thus, I assume, meaning pH is not as critical in Kodak as far as THIS is concerned, but that the Kodak formulations, at least in the C22/E-3/E-4 days would be the wrong formulation for Agfa, and I assume again, ANSCO.

If I understand this correctly the cyan layer, at the base is giving the reds, at least and this could be part of @earlz ' issue? He may need a more acidic bleach to form that mask than he gets from the Kodak bleach. If that is the case, we see some of the differences appear between Kodak and ANSCO with iodide, thiocyanide levels, pH issues in the process parts, and possibly benzyl alcohol issues. Ansco 1st developer according to Jacobsons/BJP 1971 has 10 (ml I assume) of potassium iodide solution in 1st dev vs Kodak E-3 0.0 and E-4 6.0.

Fun stuff.

 

[Mike1A]

I'd keep pH at or below 4.8 (see my Kodak F-5 comments) above.

.

Sorry, reading over both sources, I think Glafkides agrees the bleach pH in ANSCO should be 4.5 to 4.7. Interesting that his formulae continuously leave out the bleach pHs in that sections However Jacobsons show CNS bleach around pH 6 for AGFA and reversal bleach around pH 5.0 and 5.4 for AGFA / ANSCO. 4.8 might be the lowest I would go, but I think Jacobsons (based on BJP) and BJP are often more from practical experience and perhaps Glafkides is closer to the chemistry. My round about way of saying Glafkides might be right-er.

Mike

 

[Rudeofus]

That correction should also be noted about the stop bath above - ORWOColor 37 which, by the same chemistry/logic would not necessarily be hardening.

Acetate is a good buffer in the pH range between 3.7 and 5.6. It still works reasonably well at pH 6.5. It has no gelatin hardening properties to speak of, and the document @foc posted does not indicate any hardening property of ORWOColor 37.

PS: I don't have the Jacobson book, so my comments may be off.

25g of potassium nitrate will probably do to hold that pH.

Potassium Nitrate has no buffering properties in the pH range of interest to us. It is added to protect stainless steel tanks against corrosion. I have seen it (or Ammonium Nitrate) in E-6 bleach recipes as well.

Jacobsons state that for AGFA CNS films the bleach pH is critical for cyan layer mask formations, while for kodak and 3m these occur in development.

There are different types of color couplers. Some need an extra oxidation step after the reaction with PPDox to form a visible dye, until then they are leuco dyes. Several ancient bleach patents address this issue. AFAIK modern film does not have this issue.

If @earlz results suffer from lack of leuco dye conversion, the answer is not stronger acid, but stronger oxidizer. This could be an issue, if he bleached with a weak Ferric EDTA bleach or BLIX. It is a very unlikely issue, if he bleaches with Ferricyanide or a modern, Ammonium Ferric PDTA based, C-41 bleach.

 

[grainyvision]

I bleached using ferricyanide and ferrocyanide, but without boric acid as was recommended (felt unsafe to add without more certainty... meanwhile I'm adding sulfuric acid to ferricyanide ECN-2 bleach heh). There is a difference in cyan dye formation that I can see with my bare eyes when doing a quick test dipping a half sheet of C-41 bleached and fixed film into this ferri based bleach, it causes more cyan dye formation even after fixing. This is why I used this bleach in my last run of this. I have 2 sheets of this to process eventually, but I will not developer in positive. It compromises any exposure latitude I have and I honestly believe the film is just too far gone to give good results in positive at this point. Even frozen, 60 year old film can only give so much, especially these known to be unstable early color formulas. I definitely don't plan on trying to source CD-32 or anything like that. If anything I could try processing in ECN-2 developer instead of C-41, but otherwise I'm content with my current process for my occasional need for a very vintage color vibe with the unique results given here. Specifically, it gives grain you can see with your bare eyes even on 4x5 contact prints, gives a green tilted image, and some color crossing with blue shadows and yellow highlights. It's pretty unlike anything else I could imagine shooting, but don't intend to waste more film trying to figure out a better process. I will however develop longer next time I do a run of this film. The results were definitely a bit thinner than they should've been, even if the results were usable with 2 stops of over exposure

 

[Mike1A]

I bleached using ferricyanide and ferrocyanide, but without boric acid as was recommended (felt unsafe to add without more certainty... meanwhile I'm adding sulfuric acid to ferricyanide ECN-2 bleach heh). There is a difference in cyan dye formation that I can see with my bare eyes when doing a quick test dipping a half sheet of C-41 bleached and fixed film into this ferri based bleach, it causes more cyan dye formation even after fixing. This is why I used this bleach in my last run of this. I have 2 sheets of this to process eventually, but I will not developer in positive. It compromises any exposure latitude I have and I honestly believe the film is just too far gone to give good results in positive at this point. Even frozen, 60 year old film can only give so much, especially these known to be unstable early color formulas. I definitely don't plan on trying to source CD-32 or anything like that. If anything I could try processing in ECN-2 developer instead of C-41, but otherwise I'm content with my current process for my occasional need for a very vintage color vibe with the unique results given here. Specifically, it gives grain you can see with your bare eyes even on 4x5 contact prints, gives a green tilted image, and some color crossing with blue shadows and yellow highlights. It's pretty unlike anything else I could imagine shooting, but don't intend to waste more film trying to figure out a better process. I will however develop longer next time I do a run of this film. The results were definitely a bit thinner than they should've been, even if the results were usable with 2 stops of over exposure

@earlz Well experiments are always important. Sometimes with this more compromised film, I use it as B&W. Isn't QUITE as much fun, but I usually get pretty good results. I've learned something in the process at least! LOL.

 

[Mike1A]

Acetate is a good buffer in the pH range between 3.7 and 5.6. It still works reasonably well at pH 6.5. It has no gelatin hardening properties to speak of, and the document @foc posted does not indicate any hardening property of ORWOColor 37.

PS: I don't have the Jacobson book, so my comments may be off.


Potassium Nitrate has no buffering properties in the pH range of interest to us. It is added to protect stainless steel tanks against corrosion. I have seen it (or Ammonium Nitrate) in E-6 bleach recipes as well.


There are different types of color couplers. Some need an extra oxidation step after the reaction with PPDox to form a visible dye, until then they are leuco dyes. Several ancient bleach patents address this issue. AFAIK modern film does not have this issue.

If @earlz results suffer from lack of leuco dye conversion, the answer is not stronger acid, but stronger oxidizer. This could be an issue, if he bleached with a weak Ferric EDTA bleach or BLIX. It is a very unlikely issue, if he bleaches with Ferricyanide or a modern, Ammonium Ferric PDTA based, C-41 bleach.

@Rudeofus Yes the mask formation I understand was a part of the AGFA/ANSCO/DDR/USSR color films but I don't think it is an issue any more, esp the in Kodak emulsions and developers. I've used AGFA bleach before because I wanted something close to the original intention but I wasn't aware of the impact of the pH in the bleach on the color dyes/masks/etc.
Thanks for your input that helps a lot.