Thats pretty good description , way beyond what I could say.

When I first started with Pyro , 1992 -3 period, my conclusions were pretty much that the developing silver was not migrating/blooming and I did the naked bulb test and confirmed that one developer **Hutchings PMK** certainly worked better. this was a huge benifit to me as a printer as I was still using a lot of graded paper at that time and I hated burning in soft muddy highlights to get detail.
Modern VC paper and split printing were a godsend to me , on top I had the weapon of mass destruction, pyro developer.. remember I was and still doing this as a commercial process and my competitors were not in the ball park with their quick and dirty process techniques that made them fast money but their film was crap... To this day I still charge more for film not processed by my lab as I do not want to fix lazy workers film.
The rings of relief you talk about were very obvious to me , much like what you see around Transparancies.
I am not sure if the emulsions of today have changed that much since 92 , maybe they have and the effect is not as much.

Magic Bullets: I have stated in the past here on APUG about there being none.

I lied

Here are a few gems: fresh film: Pyro: Split Printing: distilled water for the dev:Rotary process with and initial hand agitation to prevent mottling: Stand Development: glass carriers: Apo enlarging lenses: laser aligned enlager:Ilford Warmtone: Dektol 1 1:5 : bleach sepia and selinium afterbath.

the list goes on and on , each worker can add their own secrets that make their work great.

I have said this before, there is no such thing as the perfect print> A lot of the workers on this site who take printing seriously are at a world class level> historically speaking there are very few printers that are making better prints before us that are coming out of the darkrooms today. What is different is the quality of the image, that is the hard part.
If you don't believe me go to as many shows , photo collectors collections and look for yourself, the prints are all within reach to all, its the imagery that is king.
The very best print I have seen in the last couple of years is one owned by Paul Paletti , it is an 11x14 print of a wave coming in to shore, the tonal range, and crispness jumps off the wall.

So if you accumulate enough good habits, work hard each year on your projects, and have some talent your work will stand out.



Quote Originally Posted by Gerald C Koch View Post
Bob,

I am not an expert on photograpic chemistry but I am a chemist. I also have been a photographer for 60 years. I have thus tried many things. PE could probably provide some more insights on what is happening. But here goes.

The principle advantage of a staining developer is that it produces not only a silver image but also a stain image. Compared to a conventional developer less silver needs to be produced to provide the same density and contrast. The stain image is grainless. Becuase of this the overall effect is a less grainy image. Less silver equals less grain. However, if you like dense negatives then this advantage is lost.

The stain is produced from the oxidation products of certain developing agents like pyrogallol, catechol, and hydroquinone. In order for the stain to form the sulfite content of the developer must be low just as it is for color developers. The stain consists of what are known as condensed polyphenols or humic acids. These compounds are highly colored and the stain is permanent. Once formed the stain is no longer effected by either the acid or the sulfite contained in such solutions as fixing baths. Humic acids are only soluble in concentrated solutions of either sodium or potassium hydroxide.

Now both tannin acid and the stain are condensed polyphenols. Tannic acid has a lower molecular weight than the stain and so is soluble in water. I think we are all familiar with that fact that animal hides can be tanned using tannic acid to make them stronger. A staining developer does the same thing. The chemical collagen in both the gelatine of the emulsion and the animal hides can be tanned thereby hardening them. Some people say that this tanning action prevents the silver grains from migrating and clumping up thus reducing the grain of the negative. With today's prehardened emulsions this alleged benefit may not be as great as in the past when emulsions were rather soft.

The tanning effect can be seen by the naked eye as it causes the emulsion to shrink producing a relief image. This also produces a refractive effect upon enlarging.
.
If the silver is removed from a negative produced by a staining developer the result is a grainless image similar to that produced by color films. Like so many things in photography this can be good or bad. Yes, there is no grain but the human eye may not perceive this image as being sharp. Anyone who has seen large color prints will experience this effect.

The amount of stain produced varies with the choice of developing agent. Some produce more stain than others. The color of the stain they produce may also be different. The developing agents differ in the conditions under which they produce a stain. Pyrogallol acts like a regular developing agent in the presence of moderate to high amounts of sulfite producing no stain image.

I hope this brief description answers some of your questions.

Jerry