Sunday, October 28, 2007

Staining and tanning

What is the difference between staining and tanning?

There seems to be confusion among some photographers regarding the terms staining, and tanning, and the terms are often used interchangeably, probably because most staining developers are also tanning developers, and most tanning developers are also staining developers, but there are exceptions, and the two mechanisms perform very different, but highly complimentary functions in negative development.

Stain

Stain is the rock star of the staining/tanning duo, and gets most of the attention and press in the ultra-geeky photo community. The oxidation products of staining developers stain the film emulsion in proportion to exposure, meaning; more stain in the densest parts of the negative (highlights) than in the thinnest parts (shadows). The stain is useful because of its color as it relates to the spectral sensitivity of the printing paper. There are basically three sensitivity-types of printing papers: Graded silver papers, sensitive primarily to blue light, Variable Contrast papers, sensitive to Blue and Green light in various proportions, and Contact papers, which are sensitive to UV light. The effect of a stained negative on Graded silver papers, and Contact papers is essentially the same; to increase contrast. The effect of a stained negative on VC papers is more complicated, due to the Yellow Filter Effect of the stain image that creates an automatic split-filter effect with simultaneously reduced highlight contrast and increased shadow contrast.

A stained negative is a composite, composed of a silver image and a superimposed stain image that combine to create print density, and therein lays the magic! To achieve a given print density, less silver density is required, meaning less grain, because the stain has no grain. And since the stain density is added to the silver density, the total contrast potential of the negative is increased, meaning greater expansion potential, which is critical for long scale and self-masking UV contact printing processes. Stain density is also immune to the Callier Effect produced by condenser equipped enlargers, so stained negatives benefit all formats and printing processes.

Tanning

Tanning is the unsung hero of acutance. Tanning developers harden the emulsion in proportion to exposure, creating a relief image, and inhibiting the migration of the developer to the depths of the emulsion, and between areas of high and low densities, simultaneously reducing the appearance of grain and increasing apparent sharpness. Hardening is proportionally greater in the highlights than in the shadows, so shadow areas are developed to a greater depth in the emulsion, increasing emulsion speed by the compensating effect.

Synergy

Staining and tanning each deliver great advantages in film development, but in combination represent an almost magical set of characteristics that seem to defy conventional wisdom on the subject of developer formulation. It’s important to remember that conventional wisdom is based almost entirely on non-staining/tanning developer formulation, and very little has been written on the subject of staining/tanning developers over the last century, and much that has been written is ill informed or just plain nonsense, so when you’re told staining/tanning developers produce coarse grain, or give away emulsion speed to produce enhanced sharpness and tonality, so they’re only really good for large format contact printing, consider the mechanisms of staining and tanning and the benefits they confer to all formats.

16 comments:

Juan said...

Glad to see you back, Jay. Hope things are well.
juan

jdef said...

Hi Juan.

I had this little article in an old file, and thought it might be useful to someone. Thanks for the kind words.

kmag said...

Hello Jay,
It is great to hear from you again, I have been checking back occasionally to see how you have been doing. It has been a rough year for many of us. I have been having a fantastic time with your 510-pyro as well as your GSD-10, they are all I use.
I hope to hear more from you.
Kurt

kmag said...

Hello Jay,
It is great to hear from you again, I have been checking back occasionally to see how you have been doing. it has been a rough year for many of us. I have been having a fantastic time with your 510-pyro as well as your GSD-10, they are all i use.
I hope to hear more from you.
Kurt

jdef said...

Hi Kurt.

thank you for taking the time to write, and for the kind comments. I think 510-Pyro and GSD-10 cover a very wide range of uses. I was never happy pushing film with 510-Pyro, but GSD-10 seems to fit that bill very well. If you have images to post, I'd love to see them.

kmag said...

I am afraid that I don't have a scanner, everything is done in a darkroom. If you want I can send some in the mail for you. I also tried FX-2 and was not impressed, especially when I have GSD-10 available. FX-2 is way to contrasty and I think hard to print because of it. With GSD-2 I have more latitude with exposure and they print great.

jdef said...

Hi Kurt.

I too find GSD-10 easy to work with, and I don't think it gives away anything in sharpness or gradation for the convenience. I have a scanner, but am a complete novice in its operation, and I've noticed that scans of GSD-10 negs seem to exhagerate grain compared to prints from the same negs. If you have development times worked out for films with GSD-10, you might consider posting them at the GSD-10 blog. GSD-10 is an unusual developer, and it might be difficult for new users to ballpark a starting development time for a given dilution without some guidance. Thanks for your comments, and I wish you continued success.

JeffK said...

Hi Jay, great to see you posting again!

I've had some problems mixing my own 510-Pyro. Any idea what's going on? Here's a link to the photo dot net thread about the issue:

http://photo.net/bboard/q-and-a-fetch-msg?msg_id=00NJN9

Jeff Kelley

jdef said...

Hi Jeff.

I'd guess more heat and more stirring would solve the problem, it always has for me. I wouldn't try to use it until I had everything in suspension. It might take more heat and more stirring than you estimate necessary, but when it's had enough of both, everything dissolves, and stays dissolved. Good luck.

JeffK said...

Hi, Jay.

I bought a used magnetic stirrer off ebay, reheated the 510-Pyro and let it stir for an hour.

Everything dissolved.

Thanks,

Jeff

mike marcus said...

Hi Jay

I read on apug that you have been experimenting with pyro-glycin-TEA

Do you have any results to report?

Jay said...

Hi Mike.

I experimented with a glycin/pyro developer, but found no improvements over 510-Pyro, so I abandoned that line of investigation. I settled on three developers; 510-Pyro for almost everything, Hypercat for maximum sharpness and compensating effects, and GSD-10 for stand development/push processing. There are links to blogs for those developers here, if you're interested. Thanks for the note, and let me know if I can be of any help to you.

Jay

mike marcus said...

I am looking at Pyro/Glycin/TEA developers both because I want to use pyro for stand development and because I love the tonality of each of these two agents and am interested in what look I can create from this combination. I am planning on using 510 pyro as a point of departure.

I wondered if you could answer a few questions.

1) Did you find Glycin and Pyro to be particularly superadditive?

2) What did you find was the result of varying the ratio between the two agents?

3) When you say that you found no improvements over 510, were the results at least as good?

4) What is the purpose of the phenidone in 510 pyro? to increase speed?

Many thanks in advance

Mike

jdef said...

Hello Mike.

It has been a while since I worked with pyro/glycin/TEA developers, and I don't have my notes handy, but I'll try to relate my experience and answer your questions as best I can.

I didn't find pyro/glycin particularly superadditive, and the two agents made for a slow working developer, similar in characteristics to a pyro/ascorbate developer.

Increasing the proportion of Glycin:pyro reduced stain formation without appreciably increasing activity.

A pyro/glycin/TEA developer was not as good as 510-Pyro in the following ways: slower working, more temperature sensitive, reduced emulsion speed, increased grain, more expensive, and glycin is only slightly soluble in TEA. I found no improvement related to stand development over 510-Pyro, which is superior in every way.

Like all of the constituents of 510-Pyro, phenidone serves more than one purpose. As a fast working, low contrast agent, it reduces development times and increases emulsion speed, and because it is extremely regenerative, it also increases capacity.

A pyro/glycin/TEA developer can be made to work, and I'm sure one could be refined and optimized beyond what I did, but my own objective analysis of its potential made it a dead end proposition when compared to 510-Pyro. 510-Pyro gives shorter development times, increased emulsion speed, reduced grain and similar performance with reduced agitation compared to PGT. As for tonality, I saw no improvements with PGT over 510-Pyro, but that's a very high standard to excede.

I was attracted to the idea of making a PGT developer by some of glycin's unique characteristics, particularly its low-fog and antioxidation characteristics. Phenidone tends to fog when used with carbonate alkalies, so it must be used very carefully in a staining developer, where fog can be ruinous. Glycin did make for a low fog developer in combination with pyro, but no less fog than 510-Pyro produced. One perceived advantage to the PGT developer was that it used only two agents, pyro and glycin, and that simplicity appealed to me. My problem was that I could not get its performance to match that of 510-Pyro, and the question ultimately became one of superadditive vs single agent developers; each has vices and virtues. For efficiency, capacity and as an all-purpose developer, superadditives are hard to beat, but single agent developers allow one to maximize the special characteristics of a given agent, which is what I tried to do with Hypercat and GSD-10, for catechol and glycin, respectively.

If I can find my PGT notes, I'll post my formula in case it's of any interest. If there's anything I can do to help, please let me know. Good luck.

Jay

Ken Bures said...

I am interested in trying 510-Pyro. This will be the first time I've used a pyro developer, so my knowledge at this point is just what I have read. In reading about them, there are comments about what specific type of short stop or fixer to use, and about putting the negatives back in the developer after fixing to enhance staining. Could you give me some recommendations on the steps/chemicals following the developer when using 510-Pyro - i.e. short stop, fixer, washing, etc. And while I'm at it, are there any special chemicals or procedures that need to be done following the use of a glycin-based developer like GSD-10? I use Kodak TMX 120-size film in stainless steel reels/tanks.

Ken Bures

jdef said...

Hi Ken.

I use a plain water rinse instaed of a stop bath; fill with plain water at the same temp as your developer, invert tank 5 times, dump, refill with plain water, invert ten times, and dump, then fix. I used Kodak Rapid fix without the part B hardener for years with excellent results, and in my testing I found the claims that an acid fix reduces the stain to be highly exhaggerated, and impossible to detect without a very accurate testing procedure, so use whatever fixer you have on hand and don't waste a lot of time worrying about it. Returning the film to the used developer as an afterbath is a relic of misguided advice from Gordon Hutchings and adds nothing beneficial to the printing qualities of the negative.
Since GSD-10 is not a staining developer, there are no issues with acid stops or fixers. The thing to keep in mind when using GSD-10 is its sensitivity to temperature. I don't recommend using GSD-10 below 70F, and with the superior hardening of TMX, you can safely develop at much higher temps for shorter development times, if so desired. TMX in MF is virtually grainless in either developer up to 16X20, or so, but I think you'll find 510-Pyro to produce slightly finer grain than GSD-10, and GSD-10 might be slightly sharper. 510-Pyro will produce full film speed and GSD-10 about one stop more with stand development.
Either developer can be used in a completely conventional way, with normal development times and agitation, and both are very flexible as well. If you intend to print your stained negatives on VC papers, there are some issues you should be aware of, having to do with VC paper's response to image stain and contrast filtration. Simply put, pyro stain adds yellow filtration which should be neutralized by magenta filtration for normal contrast on a middle grade of paper. When you place your stained neg in your neg carrier and project the image onto your easel with white light, the image will appear yellow-green. Add magenta filtration until the image appears neither yellow nor magenta, but fairly neutral. At that point, you can treat a stained negative like any other and add magenta to increase contrast, or reduce magenta to reduce contrast. The actual issues are a little more complex, but that's the gist of it. Good luck and let me know if I can be of any help.