Minimal Agitation Negative versus Tray Processed Negative

[minh0204]

Pardon my jargon illiteracy, but what does EMA stand for? Extremely Minimal Agitation?

[Alan9940]

Pardon my jargon illiteracy, but what does EMA stand for? Extremely Minimal Agitation?

Very close... Extreme Minimal Agitation

[bob carnie]

That's a very good question, I can't say for absolute but my gut tells me the hardening process comes to completion at some point. I believe it may take longer with an EMA type of development but in end, say 5 minutes rather than 2 minutes the entire emulsion will be uniformly hardened.

Thanks for reaching out

From my understanding, as the silver blooms out with development, the tannin effect hardens around the silver and stops blooming, therefore allowing the highlights to set first, mid-tones second and shadow last. Gordon Hutchings book on Pyro explains this well and IMO it is the most powerful advantage of pyro based developers.

[Steve Sherman]

From my understanding, as the silver blooms out with development, the tannin effect hardens around the silver and stops blooming, therefore allowing the highlights to set first, mid-tones second and shadow last. Gordon Hutchings book on Pyro explains this well and IMO it is the most powerful advantage of pyro based developers.

A very good explanation and I would agree the tanning effects of Pyro developers are a major player in the acutance seen in Pyro processed negs. It should also be noted there are two main Pyro developing agents, Pyrogallol Acid, which many popular Pyro formulas used such as PMK Pyro, Rollo Pyro, ABC Pyro, WD2D are the most common. PyroCat HD is formulated from Pyrocatechin or Catechol. The Pyrocatechin developing agent when compared with Pyrogallol operates in a higher pH and therefore is more stable, does not oxidizes as quickly and provides a finer grain structure, especially important to roll film and small sheet film users. Pyrogallol based Pyros do not preform nearly as well as PyroCat HD when using the EMA technique to process most any film

[sanking]

From my understanding, as the silver blooms out with development, the tannin effect hardens around the silver and stops blooming, therefore allowing the highlights to set first, mid-tones second and shadow last. Gordon Hutchings book on Pyro explains this well and IMO it is the most powerful advantage of pyro based developers.

I agree with Bob in that the most powerful advantage of pyro type staining and tanning developers is the hardening, not the stain. From an article I wrote a long time ago.

"Highlight separation, sharpness and acutance are increased because Pyro gives more pronounced edge effects than other developers. This is due to the fact that there is very little migration of silver halide during development, resulting in a more precise reduction, which enhances sharpness, and because Pyro tans and hardens the gelatin during development, thereby reducing the effects of irradiation (scattering of light in the film emulsion) and infectious development (spreading of silver development beyond the exact image boundaries)."

The use of a Pyro type developer with EMA development does not, of course, preclude other types of post-development controls, including various forms of masking. Or for that matter, scanning and digital post-processing.

Sandy

[bob carnie]

Steve pointed out earlier in one of his posts about the fact if you look at a pyro negative from an angle you can actually see the relieve surrounding areas in the image, I have never seen this with any other developer than pyro , but I do see this in my negatives when I have used pyro.