So, what is a "modern" emulsion? I've read that the PMK formula is the best modern formula. Why is that? What is a modern emulsion?
So, what is a "modern" emulsion? I've read that the PMK formula is the best modern formula. Why is that? What is a modern emulsion?
Modern emulsion, Tmax, Delta - t grain or core shell technology. Pmk is a newer formula for pyro developers, pyro in older formula like ABC tended to unevenly stain film and in newer emulsions this can be a big problem, since the emulsions are thinner. With older emulsions that were thick you can dodge the areas when printing if needed to mute the problem.
"Great things are accomplished by talented people who believe they will
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Warren G. Bennis
www.gbphotoworks.com
PMK is modern in that it addresses some of the preservation issues that plagued older formulas. PMK uses two solutions with good keeping properties instead of three solutions with inconsistent keeping properties, and PMK works at a lower pH than older pyro/soda developers, which makes it better suited to modern emulsions. Older emulsions required more active developers to keep development times reasonable, and those more active developers produced more grain.
There are also a lot of other, newer Pyro formulations than PMK which also work very well with modern emulsion formulations. Pyrocat HD/MC, 510 Pyro, WD2D are just a few that spring to mind. PMK is fine if you are doing tray development. It has two downsides - the pyro stain tends to form overall, adding additional density in the shadows in excess proportion to the silver density, resulting in longer printing times, and it also oxidizes very rapidly, so it is ill-suited for rotary processing. Also, you generally need to add an extra stop of exposure to negatives you plan to develop in PMK. This is not so with some of the other Pyro variants.
When I was 16 I thought my father the stupidest man in the world; when I reached 21, I was astounded by how much he had learned in just 5 years!
-appropriated from Mark Twain
"Great things are accomplished by talented people who believe they will
accomplish them."
Warren G. Bennis
www.gbphotoworks.com
One thing I like about PMK is that, until it is mixed, the two solutions are remarkably
stable and don't seem to oxidize at all, even with the glass bottles containing 95% air for months on end. Once the A&B concentrates are mixed, however, oxidation is
fairly rapid; so this is not the best developer for drum use. I don't get any significant rise in fbf density or border statin on modern thin-emulsion films. About the only film still around resembling an old-school thick-emulsion film is HP5plus. It will base stain a bit, but otherwise responds wonderfully to PMK in tray development.
I think when the literature references "modern emulsions" it refers to almost all films made after WWII, when thin, hardened emulsions were developed for aerial recon. I think Controlled Crystal Growth Technology emulsions like Tmax, Acros, Delta, etc., represent an evolutionary step beyond what are considered "modern emulsions" as opposed to thick, unhardened ones made before the war.HP5+ is certainly a "modern emulsion", but some claim the former Fortepan 200 was a thick emulsion film.
Yes. I use PMK because it was a coin toss with pyrocat HD for cheap and long lasting stock. PMK works well for me, and it will be a long while before my $20 supply runs out. I will try pyrocat HD sometime, but have to restrain my curiosity from trying too much different stuff at once, when I should be learning to do the best with what I have. I'm a photographer first not a chemistry geek.
I expose half a stop more (iso 320 instead of 400 with tmy2), with PMK, but many people do this anyways for a variety of developers with a variety of films as they figure out their preferences. They often fault the film as being optimistic in it's speed rather than the developer or whole process. I'm not blaming the developer or the film, just saying what works for me and gets complicated assigning blame with so many variables. I can shoot tmy2 with xtol1+1 and use it at 320 or 400.Also, you generally need to add an extra stop of exposure to negatives you plan to develop in PMK. This is not so with some of the other Pyro variants.
I don't use a densitometer, but PMK processed TMY2 doesn't look abnormally dense compared to xtol1+1 developed film. Yes there is a slight tint to it from the stain. I don't do the set aside the used developer to stain it more thing, which is unnecessary and perhaps causes the needless stain fog referenced but not quoted.
Highlights are going to appear a little different on the negative and be hard to visually light-table judge initially because you use PMK on purpose for less linear results than xtol or d76. A pyro developer really stands out for developing photos shot in the harsh sunny snow scenes for example.
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