Developer capacity, D-23, and dilution

[Ulophot]

Among the accusations ever leveled at me, exhibiting a command of math and chemistry are not to be found. I'm running a series of tests with D-23, from N+2 to extra-compensating, in both tray and rotary tank (Jobo on a Uniroller). I'd like to be sure I'm not introducing an unrealized variable in my dilutions. My weekly available time for photography, at present, is constrained.
D-23
D-23 capacity, straight, is listed at the equivalent of 16 4x5s per liter (4 8x10s, 320 sq. in.). My question is the minimum amount of this stock solution required when it's diluted; I've been unable to find a clear answer. Specifically, I would think that a liter a working solution of 1:1 would then process 8 (one-shot), one of 1:2 would process 4 and one of 1:3 would process 2. Therefore, my logic runs, a could process only 1 sheet in a half-liter of 1:3; that would be 4 ounces of stock in that working solution to process a single 4x5 sheet. Is that right?
What I have seen often in posts on various sites, is suggestions like, "Well, I would double the total working solution at that dilution, to avoid early exhaustion..."
Since my calculation methods are not infrequently flawed, I will grateful for any scientific correction.

[Jim Noel]

The minimum amount of stock solution required is the same whether straight, or diluted. If less is used there is a great chance of under-development due to developer exhaustion.

[xkaes]

You've got the general idea right -- as you dilute the developer you need to increase the time. A good starting point, is DOUBLE the dilution, DOUBLE the time. But that only goes so far, as mentioned. Developers wear out -- AKA exhaust. This happens sooner as the developer is diluted -- AND it will impact the highlights and shadows deferentially, so the contrast will change. But whatever dilution you use, for however long, you need to run tests to examine the film speed and the contrast.

[Sal Santamaura]

The minimum amount of stock solution required is the same whether straight, or diluted. If less is used there is a great chance of under-development due to developer exhaustion.Concisely, eloquently correct. No further elaboration required or equivocation appropriate. Great work, Jim!

That post ought to be put on the home page. :)

[Tim Meisburger]

Right, but I develop 4 sheets with about 250ml all the time. When I was shooting Shanghai, I used to develop four sheets with 80ml, but that was definitely not enough for FP4. So, my guess is that different films will require different amounts of developer, but that is just a guess...

[LabRat]

D-23 is to be used straight, as it gets too weak for normal Dmax when diluted (even at extended time)...

Steve K

[LabRat]

Let me add about D-23 dilution... The excess of sodium sulfite is slightly alkali enough to accelerate metol into development, but it needs a lot present to do it... By even a 1:1 dilution, it cuts that by half, so not enough to activate development much...

Other developers usually contain an additional alkali to maintain the pH level even at higher dilutions, so it can be diluted...

Been a long time since using D-23, but as I (barely) remember, the capacities you listed were about right, as you can use it several times, but a slight decrease in Dmax creeps in...

I remember D-23 as having a nice tonal graduation, but gets a little mushy the bigger the enlargement... (I now prefer a dilute low sulfite one-shot developer that allows better edge effects, and is slightly compensating by developing highlights to exhaustion, but with very good shadow detail, and non-dense highlights that one can easily print additional steps into...)

Steve K

[Ken Lee]

D-23 is to be used straight, as it gets too weak for normal Dmax when diluted (even at extended time)...

That hasn't been my experience. With regard to contrast curves and film speed, my D-23 1:1 images are basically the same as those I have made with D-76 and Pyrocat HD at comparable dilutions. To prove this to myself I did a rigorous BTZS test of HP5+ and compared the curves with those from D-76 and Pyrocat HD: they were virtually interchangeable. One test like that was convincing enough for me.

See http://www.kennethleegallery.com/html/tech/D-23.php for a few sample images.

[mdarnton]

I remember D-23 as having a nice tonal graduation, but gets a little mushy the bigger the enlargement... (I now prefer a dilute low sulfite one-shot developer that allows better edge effects, and is slightly compensating by developing highlights to exhaustion, but with very good shadow detail, and non-dense highlights that one can easily print additional steps into...)

Steve K

My experience also. What is the developer you use but don't name?

[Ulophot]

Thanks to all.
As I have been simplifying most factors of my work, returning after about 12 years, D-23 seemed a good choice for cost, ease, and versatility with the other characteristics I want for location portraiture in MF and 4x5 with a sinle film HP5+. My tests are running from very compensating to N+2 or so; so far I've had no trouble approximating N-1 to N+2 using 1:1. I'll get to testing straight times, and to more compensating results for very long-range subjects using higher dilutions and moderated agitation, perhaps even 2-bath, if needed. I just want to know what I can do so that I can respond to existing illumination as I choose. Per Ansel, chance favors the prepared mind.
A colleague recently suggested the original Gainer's developer -- also cheap and simple -- which I'll try provisionally; I could use in 4x5 the additional speed he seems to get; not sure I want higher acutance. My results with D-23 so far have not supported EI400; I'm back to 200 or 250, as I was for decades; I thought I might do a little better, but I can live either way. I'll settle on whichever developer provides a negative with the qualities I want. I'll be printing silver; no scanning for me, except from prints to post occasionally on line (here and Flickr).
Again, thanks.

[Ken Lee]

Since you're considering HP5+ in D-23 1:1, you might find this discussion helpful: http://www.largeformatphotography.info/forum/showthread.php?135870-BTZS-Metering-Question&p=1368910&viewfull=1#post1368910 and subsequent posts.

I shared the development/contrast curves I discovered while doing a BTZS test with this combination. I'd be surprised if your results were considerably different. I shoot it at 200 since the difference between 200 and 250 is a mere fraction of an f/stop, beyond our ability to accurately meter a scene.

[Ulophot]

Thanks, Ken. Your exceptional work/site contributed significantly to my choice of D-23 when I started looking around early this year. I appreciate the charts and precision for what they are; I'll follow my empirical testing without that degree. I contact on Multigrade RC and print on Ilford Warmtone semi-matte (with Strand's stand-oil varnish finishing the print). Already a number of variables are thus introduced, even from contact to straight print on the two different papers, but it's something I know and will find my way back to. It has just been a good while (or, not so good...). So, for instance, when I looked at a new test neg, I though I had a good Zone II, but it was I in the print -- on the RC, albeit is different from my fiber choice. A scientific approach is, I think, essential to avoid wild variables. The portraiture I'll be doing will have lots of its own. If I know I can handle them reasonably well in exposure and development, I'm happy; the art of printing is at least half the fun.
Philip U.

[Ken Lee]

I contact on Multigrade RC and print on Ilford Warmtone semi-matte (with Strand's stand-oil varnish finishing the print)

Could you explain this method of varnishing ?

[LabRat]

My experience also. What is the developer you use but don't name?

Hi Michael,

I had used D-23 and D-25 many years ago, but wanted something sharper cutting... (But D-23 was good for taking the edge off T grained films that I don't use...) D-76 tended to be a bit contrasty and hard out here in the Cali sun (but good for flat overcast & foggy conditions), so I hit the books for a formula that had about equal amounts of metol & hydroquinone, and after much searching, I found in the BJP a diluted Crowley variation of the old DK-50 formula, where a standard stock solution of DK-50 is mixed (A), and another B solution of 80 grams of Kodalk per liter into water, where to make a working solution you take 2 parts of DK-50 stock (A), 1 part of Kodalk (B), and seven parts water... (So a liter of working solution is 200ml A, 100ml B, and 700ml water) Development times are just like D-76, but holds highlights much better, fine sharp grain, cleaner working, a restrainer that controls fog, and with slight overexposure/underdevelopment, the grain pattern just follows shadow lines but does not cover image at normal EI... Use one shot... Easy to mix, and stock lasts for a good time... Maybe not for denser alt process negs, but the good but non-dense Dmax is perfect for enlarging + scanning, and great for all formats...

FYI, I'm going to be off-line for awhile (for a walkabout, shooting, and finding a new studio, home, life, etc) I'll check in, but I hope no one burns down the house while I'm gone, so in the meantime, get out there and darken some silver!!!

All good things to y'all!!!

Steve K

[Ulophot]

Could you explain this method of varnishing ?

The varnishing, for those unfamiliar, is a means of regaining tonal range with semi-matte fiber papers, whose surface, when dry, otherwise diffuses the light so as to make the middle and, especially, lower tones appear far less dense than the wet print, diminishing the overall as well as local contrast. Strand, who liked neither glossy nor matte surfaces and preferred semi-matte papers (some will remember the days when we had silver papers with a wide range of "lustre" and semi-matte surfaces and textures), experimented with a wide range of waxes and varnishes, finally settling on this one of artists' stand oil and good quality artists' turpentine, such as Windsor Newton. When his close friend Walter Rosenblum demonstrated this for me on one of my Portriga 118 prints, bringing it back to life, he said that prints of his had shown no ill-effects or yellowing after decades. My experience is the same.

It has been long enough that I don't remember the dilution I was given as a suggested starting point. I think it was about 1:4, stand oil to turpentine, but I recall making thinner mixes, perhaps because the stand oil had been around for a number of years. In any case, the dilution is not critical. The turpentine carries the oil into the print and evaporates.

The varnish solution can be mixed in a small glass, small-mouthed bottle. Once prints are toned and drymounted (N.B.: the varnish will curl unmounted prints), one uses a cotton ball wetted with very-well-shaken varnish solution and applies it to the print surface using overlapping small circles. If the print is trimmed to its image area on a large matte, a piece of thick (e.g., 28-lb or more) normal white paper can be used placed edge-to-edge with the print to avoid varnish getting onto the matte; care is, of course, needed. After application completion, a few minutes are given, then fresh cotton balls are used to distribute the oil remaining on the surface and remove excess. The print surface should then appear evenly finished, with no areas or streaks of other excess oil. The print is then stood somewhere to finish drying for a day or two. If streaks appear, the varnish can be used again to even them out with the same procedure, or, Walter told me, the turpentine alone can be used to draw the oil out of the print.

One may wish to practice on a few extra prints first, to gauge dilution and technique.

For Strand fans, I just discovered that the Smithsonian has a 5-hour-plus recorded interview of Strand conducted by Rosenblum and another friend, art historian Milton Brown, from 1971. It is available for auditing by appointment in Washington DC and New York.

[Ken Lee]

Thank you for taking the time to explain the process.

Do you have any idea whether it could be used on an inkjet print ? I can try if of course, but wonder if the solvents would immediately affect the pigments, the binder etc.

Does this work for Pt/Pd prints ?

I ask because I make matte carbon pigment prints (Piezography K7 Carbon).

[Ulophot]

Hi, Ken. No clue regarding anything but B&W silver prints; that's all I have used it for and all I engage in (for serious work) now. Maybe one of the chemists or manufacturer's reps will know.

[neil poulsen]

Decades ago, I took a class from Harrison Branch at Oregon State University, and he recommended applying Treewax using cheese cloth to mounted, glossy paper prints. It gave the prints a nicer look with more depth to the shadows.

I've not continued this practice with the printing I do currently. However, I still have some of those prints, and I've not seen any particular ill effects, either.

[mdarnton]

Hi Michael,

I had used D-23 and D-25 many years ago, but wanted something sharper cutting... . . . .
Steve K

Thanks for that! It sounds exactly like the developer I have been looking for!

[mdarnton]

Do you have any idea whether it could be used on an inkjet print ? I can try if of course, but wonder if the solvents would immediately affect the pigments, the binder etc.



I use a Canon Pro-100 for my black and white prints on Hahnemuhle photo rag pearl paper. I noticed that this paper, which I love, was very vulnerable to fingerprint damage, and one day in frustration I tried wiping the mess off with odorless paint thinner, which is a turpentine substitute. I was very surprised to find that the marks were in overspray dust, not the print itself, and the paint thinner did an perfect job of cleaning the prints, after which the surface turned out to be quite tough, so now I do this to all of my prints. So there's an answer for that combination.

[Sal Santamaura]

...Do you have any idea whether it could be used on an inkjet print ? I can try if of course, but wonder if the solvents would immediately affect the pigments, the binder etc...


I use a Canon Pro-100 for my black and white prints...I have no idea whether it would make a difference, but the PRO-100 uses dye, not pigment inks. Paint thinner might affect pigments but not dyes.

[Ulophot]

I have just (Jan 9, 2018) come across an article by Walter Rosenblum that includes his varnished technique, which I described almost correctly in my earlier post in this thread. The article is in Fred Picker's newsletters, #78, June '94, page 898 in the collected PDF recently linked in the forum. I quote:

"I feel that a glossy surface prevents the viewer from moving into the image, which after all, is a primary requirement of a successful photograph. However semi-matte paper, which I use, reflects little light and as a result has a reduced tonal scale so I varnish the surface with a solution consisting of a small amount of Stand oil dissolved in Windsor Newton artist's turpentine (approximately two tablespoons of oil to 8 oz. of turpentine.) I first dry mount the photograph on to a piece of one ply museum board since I like the photograph to lie flat under the window mat which I use. The museum board is trimmed to the same size as the print. I then apply the varnish with a ball of cotton and then rub it all off immediately. What is left is a microscopic residue that gives life to the matte surface without a gloss. …

"It is my belief that there is one definite rule that should be followed in the darkroom... one should always exhaust every possibility in terms of paper, developers, and exposure in order to produce a fine print."

This is taken from "Printing in Black and White, Some notes on printing for the young photographer", a joy to read.

[LabRat]

I have just (Jan 9, 2018) come across an article by Walter Rosenblum that includes his varnished technique, which I described almost correctly in my earlier post in this thread. The article is in Fred Picker's newsletters, #78, June '94, page 898 in the collected PDF recently linked in the forum. I quote:

"I feel that a glossy surface prevents the viewer from moving into the image, which after all, is a primary requirement of a successful photograph. However semi-matte paper, which I use, reflects little light and as a result has a reduced tonal scale so I varnish the surface with a solution consisting of a small amount of Stand oil dissolved in Windsor Newton artist's turpentine (approximately two tablespoons of oil to 8 oz. of turpentine.) I first dry mount the photograph on to a piece of one ply museum board since I like the photograph to lie flat under the window mat which I use. The museum board is trimmed to the same size as the print. I then apply the varnish with a ball of cotton and then rub it all off immediately. What is left is a microscopic residue that gives life to the matte surface without a gloss. …

"It is my belief that there is one definite rule that should be followed in the darkroom... one should always exhaust every possibility in terms of paper, developers, and exposure in order to produce a fine print."

This is taken from "Printing in Black and White, Some notes on printing for the young photographer", a joy to read.

Maybe, but the initial claim does not make much sense (unless it is a typo), about not being able to "move into an image" because of a glossy finish (!?!!!), as glossy can be very reflective, but also the clearest surface...

Seems like making problems where they don't exist...

Steve K

[Ken Lee]

Maybe, but the initial claim does not make much sense (unless it is a typo), about not being able to "move into an image" because of a glossy finish (!?!!!), as glossy can be very reflective, but also the clearest surface...

Seems like making problems where they don't exist...

http://www.kennethleegallery.com/images/forum/MuseumGlass.png

Perhaps the writer was referring to interference from ambient lighting. Matte prints are more or less immune to it when displayed behind a minimally reflective surface.

[LabRat]

But the texture of a matte print produces a fine, reduced, but even highlight reflection overall, that mostly affects the darker regions???

But still a surface texture that "gets in the way" of directly viewing the image...

Some like it/some hate it... But matte can remove the appearance of much the modeling of the "pseudo-3D effect" on a fine silver print...

The best were the very fine textured dead matte surfaces, but those paper surfaces have vanished, replaced with intrusive "pearl" surfaces...

(I'm fine with glossy dried matte DWFB, BTW...)

Steve K

[ParkerSmithPhoto]

The varnishing, for those unfamiliar, is a means of regaining tonal range with semi-matte fiber papers, whose surface, when dry, otherwise diffuses the light so as to make the middle and, especially, lower tones appear far less dense than the wet print, diminishing the overall as well as local contrast. Strand, who liked neither glossy nor matte surfaces and preferred semi-matte papers (some will remember the days when we had silver papers with a wide range of "lustre" and semi-matte surfaces and textures), experimented with a wide range of waxes and varnishes, finally settling on this one of artists' stand oil and good quality artists' turpentine...

I know this topic is a bit old but I hope I can add something. I work with a collector here in Atlanta who has several portfolios of Strand prints from the end of Strand's life. I have studied these prints (without glass) on several occasions and I can assure you that Ilford's MGWT SEMI-MATTE surface is a dead ringer. I know Strand said he preferred something in the middle, however, his prints with the varnish lean heavily towards the matte surface, with just a little lustre.

In attempting to recreate this look with inkjet papers, I settled on Eboni pigments with a hot press paper. I then sprayed the print very lightly with MATTE acrylic spray, let it dry, then did another light spray. Then, I gave it several light coats with a SATIN acrylic spray. If you rush it, you will get a drip and have to toss the print in the trash. If you are patient and build it up slowly, you end up with one of the loveliest print surfaces you've ever seen.

I showed a series of portraits to the director of Atlanta Celebrates Photography and she said "oh my god, these look like Paul Strand prints!" They really are quite beautiful and wouldn't be out of place in a Strand exhibit.

[Joe O'Hara]

That hasn't been my experience. With regard to contrast curves and film speed, my D-23 1:1 images are basically the same as those I have made with D-76 and Pyrocat HD at comparable dilutions. To prove this to myself I did a rigorous BTZS test of HP5+ and compared the curves with those from D-76 and Pyrocat HD: they were virtually interchangeable. One test like that was convincing enough for me.

See http://www.kennethleegallery.com/html/tech/D-23.php for a few sample images.

Seconding Ken here. I use D-23 1-1 all the time and have no problem getting all the contrast I can stand, and that's using a diffusion enlarger and Ilford MG Warmtone, which is softer than MG Classic. FWIW I run everything at 70 F because I'm too cold in a 68 F room.

Also, I always use 100 ml of stock D-23 per sheet of 4x5; overkill maybe but developer is cheap at the volumes I use it. So 4 sheets of 4x5 in a Jobo 3010 tank takes 800 ml of diluted solution. Also I mix and dilute with distilled water.

[ParkerSmithPhoto]

I've recently been doing some tests with D-23 and also with Beutler's formula, and something I call P-23, which is basically Beutler's formula with Sodium METABORATE instead of sodium carbonate.

D-23 has some of the loveliest midtone and highlight contrast but lacks a bit for sharpness. The P-23 formula really does crisp up the negatives without altering the overall tonality, and the Beutler's is just a hair sharper with the similar tones but it has a slightly higher base fog which seems to be just enough to push some of the midtones up by about 1/6 stop over the P-23 formula. It's probably nothing I would notice without a direct 1:1 comparison print. Beutler's is also a touch grainier, though totally acceptable to my eyes, even at 16" with HP5. With FP4 (really the best film available today), all of these developers are fantastic and the added sharpness from the P23 or Beutler's formulas hardly affects the grain.

I had spent the previous two years working with Pyrocat-HD and have some admiration for it. That being said, the D-23 variations are perfectly lovely, and the ease of use of a 2 or 3 chemical formula, not having to mix a super-saturated "B" solution and not having to fool with the toxicity of Pyro is A+ in my book. I process for a negative that looks a bit flat to my taste and they all print beautifully on a Grade 3-4 paper. In fact, I can run both FP4 and HP5 in the same tank and get fine negatives. I also appreciate a little more "tooth" to the grain rather than the super-smooth P-HD look. (I did also experiment with stand development and found it to be kind of gross, at least for portraits. Plus it's just a big hassle.)

FWIW, I used Barry Thornton's Two Bath for many years and at some point realized that the A Bath was perfectly fine on its own, and the only thing the B Bath did was inflate the highlights and introduce a variable that was hard to control. So, when I make reference to D-23, I am actually referring to Thornton's "improved" version which is 6g metol and 80g sulfite in 1L.

Hope that helps!

[mdarnton]

The "varnish" suggested isn't a varnish, but simply oil in a solvent. Think in terms of oiled paper, how it becomes more translucent, becoming like waxed paper. I don't doubt that some added translucency of both the gelatin and the paper under it would result in a whole different look, possibly more welcoming, but I'd hate to be the conservator in 100 years who has to deal with the subsequent yellowing of everything. If you're working for now, I guess that doesn't matter as much.

[Ulophot]

That's a good point, Michael, regarding the varnish. Yes, just oil. It's a linseed oil, the same used by oil painters, if I am not mistaken, and dries. Not being a chemist, so I can't comment on its keeping properties. Walter had told me that it is removable with artist's turpentine, the same way it goes in; maybe that would give a conservator the chills as well. Although my portrait work is meant for history, I don't know that its artistic quality will merit a conservator, and as much as I revere original art work rather than copies, for the obvious reasons, in a hundred years--well, I'm confident that we'll know more about physic by then, and conservation will probably be far advanced.

It will sound foolish to some, or many, to say that if it was good enough for such artists as Strand and Rosenblum, it's good enough for me. After all, Leonardo's masterpiece in the refectory has suffered terribly from his experiment. However, like the Sistine Chapel ceiling with centuries of smoke and other pollution layered on, conservators did manage to clean it. As I say, I don't expect such loving care with my history portraits, wherever they may end up. After half a century and more, prints of the two photographers finished with the stand oil are still looking very good. For me, that's okay.

[John Layton]

Renaissance Wax to varnish (Strand-inspired but a passing fad for me, obviously no disrespect towards Strand!)...but be really careful with that ball of cotton that it does not leave little fragments (impossible to remove) on the print surface!

[ParkerSmithPhoto]

The "varnish" suggested isn't a varnish, but simply oil in a solvent...I'd hate to be the conservator in 100 years who has to deal with the subsequent yellowing of everything.

I, too, would be apprehensive of what might happen to the varnish. However, my experience viewing the silver gelatin Strand portfolios, which were printed in the early 70s by Richard Benson, revealed no traces of damage or discoloration from the varnish.

Benson did note that the first edition of the gravure Mexican Portfolio had a varnish coating applied by a professional house painter with a spray gun which had since completely yellowed. See Benson's talk here (https://printedpicture.artgallery.yale.edu/photography-ink-relief-and-intaglio-printing), starting around 42:30.

I have personally viewed the second edition of the Mexican Portfolio and there is no trace of discoloration.

[Ulophot]

Strand gave a delightful account of the first Mexican portfolio varnishing during a 5-hour interview that is on file in the Smithsonian archives in both NYC and DC. He experimented with various varnishes over the years. My impression from Walter was that the stand oil one was the one he had settled on, I don;t know when. I learned it from Walter c. 1972.

[reddesert]

That's a good point, Michael, regarding the varnish. Yes, just oil. It's a linseed oil, the same used by oil painters, if I am not mistaken, and dries. Not being a chemist, so I can't comment on its keeping properties. Walter had told me that it is removable with artist's turpentine, the same way it goes in; maybe that would give a conservator the chills as well. Although my portrait work is meant for history, I don't know that its artistic quality will merit a conservator, and as much as I revere original art work rather than copies, for the obvious reasons, in a hundred years--well, I'm confident that we'll know more about physic by then, and conservation will probably be far advanced.


FWIW, linseed oil (sometimes stand oil, which is a thicker processed variant) and turpentine is a classic oil painting medium, meaning an liquid that is mixed with oils to achieve the consistency, flow, and gloss that the painter wants. A variant is to include damar varnish, but not too much varnish or it can cause problems later.

I have no experience with using this stuff on photographic paper. On canvas, the issue to be concerned about is that the canvas must be properly primed or the paint and medium can soak into the canvas fibers. My guess is that the treatment of photo paper to coat with emulsion is similar to priming. Anyway, at least the medium is something a conservator would be familiar with.

[Kirk Gittings]

That hasn't been my experience. With regard to contrast curves and film speed, my D-23 1:1 images are basically the same as those I have made with D-76 and Pyrocat HD at comparable dilutions. To prove this to myself I did a rigorous BTZS test of HP5+ and compared the curves with those from D-76 and Pyrocat HD: they were virtually interchangeable. One test like that was convincing enough for me.

See http://www.kennethleegallery.com/html/tech/D-23.php for a few sample images.

were you doing a pre-soak in that test?

[Ken Lee]

were you doing a pre-soak in that test?

Yes. I always use a 3-5 minute pre-soak.

[Kirk Gittings]

Yes. I always use a 3-5 minute pre-soak.

Thanks. I am back to my roots doing a HABS project with 5x7 in trays. I haven’t done trays in ages. I haven’t done anything but 4x5 in BTZS tubes for a couple of decades (in D-23 for the last many years after our last discussions).

[Jim Noel]

One excellent use I don;t see mentioned in this thread, replenishment.
At the college we used to have a nitrogen burst system for 4x5. A line was painted on the tank for developer indicating proper level. When a student finished they added D-25R up to the line.
At the end of each semester, after developing wellover 1,000 negatives, i took this well used developer home. I used it to intensify negatives i knew needed help in mid-tones as well as highlights, or ones i intended to use for carbon prints. The plating of silver which happened during Normal Development times produced negatives of amazingingly beautiful scale. I retired from the college 7 years ago but I still get the same results from this old, well used developer.

[Ken Lee]

One excellent use I don;t see mentioned in this thread, replenishment.
At the college we used to have a nitrogen burst system for 4x5. A line was painted on the tank for developer indicating proper level. When a student finished they added D-25R up to the line.
At the end of each semester, after developing wellover 1,000 negatives, i took this well used developer home. I used it to intensify negatives i knew needed help in mid-tones as well as highlights, or ones i intended to use for carbon prints. The plating of silver which happened during Normal Development times produced negatives of amazingingly beautiful scale. I retired from the college 7 years ago but I still get the same results from this old, well used developer.

Amazing !

See page 12 of the remarkable Kodak Chemicals and Formulae (https://skrasnov.com/wp-content/uploads/2016/07/kodak-chemicals-and-formulae.pdf) from 1949.

Apparently, D-25 is an extra fine grain version of D-23, which Kodak considers "a soft working developer of simple formula giving normal emulsion speed"

D-25 adds some Sodium Bisulfite and Kodak says "This developer requires 50 to 100% increase in exposure".

D-25R, the replenisher for D-25 and D-23 is apparetnly D-23 with some Sodium Metaborate added. My amateur guess is that the Sodium Metaborate acts a stabilizer.

[LabRat]

Amazing !

See page 12 of the remarkable Kodak Chemicals and Formulae (https://skrasnov.com/wp-content/uploads/2016/07/kodak-chemicals-and-formulae.pdf) from 1949.

Apparently, D-25 is an extra fine grain version of D-23, which Kodak considers "a soft working developer of simple formula giving normal emulsion speed"

D-25 adds some Sodium Bisulfite and Kodak says "This developer requires 50 to 100% increase in exposure".

D-25R, the replenisher for D-25 and D-23 is apparetnly D-23 with some Sodium Metaborate added. My amateur guess is that the Sodium Metaborate acts a stabilizer.

Used D25 years ago for shooting commercial 120 processing...

D23 worked ok for 4X5 and up negs for enlarging to moderate sizes, but on roll film + enlargement , D23 was a little mushy, but the D25 variant cleaned it up a little for printing... Did some variants where 7.5gm/per liter bisulfite was added which cleaned up the grain mush, but only lost about 1/3 stop in speed... Worked well, but for smaller negs found other dev formulas that produced better edge effects esp for 35mm/120 formats... Great mid-tones!!!

The Sodium Bisulfite is an acid salt, so my guess it very slightly reduces activity... Shadow areas were "cleaner" with a little more "bite"...

Steve K

[Jim Noel]

I am really happy to get a copy of this booklet. I Have worked from memory for a lot of years wishing I had one to back up my 91 year old memories.