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Pawlowski6132
8-Mar-2011, 19:44
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?

Greg Blank
8-Mar-2011, 20:04
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.


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?

Jay DeFehr
8-Mar-2011, 20:20
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.

Scott Davis
9-Mar-2011, 08:37
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.

Richard K.
9-Mar-2011, 09:34
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?

Someone should send you a couple of nice modern FP4+ negs developed in PMK.... :D

Greg Blank
9-Mar-2011, 15:31
I don't find that to be the case at all of course I mix two separate increments to eleviate oxidizing. I also use a bit of amidol in the mix.


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.

Pawlowski6132
9-Mar-2011, 18:01
Someone should send you a couple of nice modern FP4+ negs developed in PMK.... :D

Yeah right. Not likely. Who would be so kind as to do something like that for me???

;)

Drew Wiley
9-Mar-2011, 20:10
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.

Jay DeFehr
9-Mar-2011, 21:30
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.

jp
10-Mar-2011, 07:44
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.

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.


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 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.

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.

Drew Wiley
10-Mar-2011, 09:38
Jay - the expression "modern" is relative. Films like HP5 and possibly Tri-X (and certainly the old-style Fortepans) stain more aggessively than the "thinner" T-grain and tabular grained emulsions. I think most of us would classify the late great Super-XX as a an-school film. FP4 is also a bit more aggressive in its staining characteristics
than say ACROS, which is about the same effective speed in PMK.

Jay DeFehr
10-Mar-2011, 11:15
Drew,

Have you tested your assertions? I have, and my results have convinced me that all "modern" (meaning films I've been able to test) films stain about the same, whether they're CCGT films or not. For a given silver density, a given staining developer will produce a given stain density within narrow margins among a wide variety of films. I think SXX was indeed a thick emulsion film, unlike HP5+, TX, FP4+, etc., which are all modern thin emulsion films. I have used a lot of Fortepan 200 and still have a lot of it in my freezer, and if it is in fact a thick emulsion film, it still conforms closely to the silver:stain ratios of modern thin emulsion films. I think the notion that some films stain better/more than others is a popular myth based on anecdotal claims made by people who have never measured the stain densities of their negatives or compared them to others. I've read thousands of stained step wedges, and seen very little variation in silver density : stain density among them. The differences I have seen are attributable to differences in developer formulation, not in the film stocks. The best staining developers produce near the maximum stain:silver density ratios, and near zero general stain. The rest fall short in one way, or the other, or in both ways.

Drew Wiley
10-Mar-2011, 12:38
I'm not guessing, Jay. Do this all the time, and have worked with just about all the sheet films out there except Tri-X, and many roll films too. And yes, at the moment
I still have some Forte 200 in my 8x10 holders. The end result can also be tweaked by
how long an alkaline afterbath is used - a nice feature with thin-emulsion films which
don't tend to stain as much. HP5 is a little more amenable to some of the old tricks
like Super-XX was used for, so although it might not be classified a thick-emulsion film in relation to certain long-discontinued items, it behaves that way relative to the other
current film options. Got the densitometer right next to the light box.

Jay DeFehr
10-Mar-2011, 13:07
Drew,

I'm interested to know how you've conducted your testing to come to such a different conclusion than I have. I expose the film I'm testing in a sensitometer and then process them, and read the resulting step wedges with a color densitometer, comparing the readings from the different filters to calculate the difference between silver density and stain density. Whenever I compare different films at a common silver density, the stain densities fall within the margins of accuracy of my equipment and process. I've never seen any data that suggests one film produces more stain relative to a given silver density than another film processed as close to identically as I can manage. Could you provide some of your comparison data?

I've worked with HP5+, and I've never found it to differ from any other film in its class regarding its processing behavior. The "tricks" most people associate with thick emulsion films are things like 2-bath development and water bath development, and I've not found HP5+ to behave differently in these processes than other films do.

The "after bath" is another notion I've been persuaded by my own testing is completely useless, and most often harmful, adding only general stain which functions exactly like fog with graded papers, and like fog with a low contrast filter effect with VC papers. I don't know a single formulator of staining developers who recommends the practice, and I'm not surprised by that.

I'm not saying you're wrong, Drew, I'm just saying it would take a lot of credible data to convince me I am.

Drew Wiley
10-Mar-2011, 14:28
Hi Jay - I don't get any fog from afterbath. I use it selectively (tray processing of sheets, manual drum for small format). Helps improves the highlight characteristics of
films which don't stain as readily - a little longer afterbath vs a shorter one (or none).
Films like 100TMax, ACROS, Pan F, Delta100, etc are generally improved by a longer
alkaline afterbath. FP4 and HP5 require more caution or the highlight stain will become
excessive on long-scale subjects. I weigh this factor in relation to the same PMK developer. Only with HP5 or Pan F do I tweak the standard PMK mix ratios. I could give
you some FBF reading, though I can't get to the dkrm tonite. It's always much higher
with HP5 (somewhere around .15), even worse with the old Fortepan 400 dual-coated
emulsion, which I never liked anyway. With these "relatively thick" emulsions, you get
a little more infectious perimeter (surge) development than with tabular grain films.
Staining also must inevitably be related to the type of polyester or acetate used in
various film mfg, though this is a bit more difficult variable to isolate with casual lab
readings. PMK is my standard developer for general photography (vs special lab use),
so I feel extremely confident about my statements. Use it and print form it almost every week.

Jay DeFehr
10-Mar-2011, 16:43
Drew,

I hope you won't be offended if I don't share your confidence in your statements. To know how much stain is being produced, one must subtract the silver density from the total density, or silver + stain density. A FB+fog reading alone doesn't tell one anything about the contribution of stain to the reading.

Regarding the after bath, I don't know what you mean when you say:


Helps improves the highlight characteristics of
films which don't stain as readily

In what ways does it improve? And what do you mean by:


FP4 and HP5 require more caution or the highlight stain will become
excessive on long-scale subjects.

Do you mean that the contrast can be too high? I've never seen any evidence that an after bath increases contrast.

Staining also must inevitably be related to the type of polyester or acetate used in
various film mfg

Not only do I believe the above to be untrue, I can't imagine any way it could possibly be true. The support doesn't stain, the emulsion does, by a process of polymerization. If you don't believe me, strip the emulsion off of a length of film support with some chlorine bleach, and then dunk it in PMK. No emulsion, no stain.

It is possible to be mistaken about all of these things and still get good results, which is why anecdotal evidence is worth so little in the absence of sound theory, and better still, empirical data.

Drew Wiley
10-Mar-2011, 17:20
Jay - highlight characteristics, i.e., reproduction characteristic in typcial silver printing.
The whole point of the stain is to modify the printing characteristics, therefore being
able to control the amount of this stain using an afterbath, and being able to improve
the amount of stain in films which otherwise stain weakly. Pretty simple concept...
Next, by "film base" you are technically correct. I was shorthand referring to it in the
sense of base plus unexposed emulsion (borders or otherwise unexposed fresh film).
Certain combinations of plastic plus sensitized gelatin which differ from product to
product. Generally, a film which is amenable to water-bath or other old-fashioned
"thick emulsion" effects will react in a manner producing more "tanning", although this
is not a fixed rule, just a practical observation. Pyro tans. We not only rely on this with
respect to PMK, but in technicolor film base, dye transfer and wash-off relief printing,
and several technical medical applications. The tendency of FP4 and HP5 to blow out
the highlights with too much staining has been discussed on other threads. You don't
need to believe if you don't want to. I need to believe it, otherwise my prints suffer,
or need a supplementary contrast mask to tame. Had a lot of experience with this.

Jay DeFehr
10-Mar-2011, 18:11
Drew,

You seem to be suggesting that the after bath increases stain formation in the highlights, with which I don't disagree, but I'd add that it increases stain density non-preferentially, throughout the entire density range of the negtative, adding neutral density, not contrast. VC papers react differently than graded ones do, and in that case the stain also imparts a yellow filter effect which acts to decrease print contrast.

Pyro does indeed tan, and a thick emulsion can potentially show more relief than a thin one. No argument there.

If HP5+ and/or FP4+ have any tendency towards blown highlights with staining developers, it is simply a matter of over development, not over staining. Stain is proportional to silver density and a function of the degree of development. If there is too much contrast, the film has been overdeveloped. A family of curves will illustrate the range of contrast a film/developer combination can produce given various degrees of development. If you overdevelop your film, it's not the fault of the developer.

Drew Wiley
10-Mar-2011, 19:15
Yes and no. Depending. One thing I like to do with Hp5 is plus develop in order
to maximize mackie line effect and midtone expansion. With this film, PMK allows
this while keeping overall granularity visually supressed, the well-known "watercolor" effect. Since Hp5 has a pretty distinct toe, on brightly-lit subjects, the
shadows need quite a bit of exposure, hence the highlight tend to block up. Just a
variable contrast split-printing technique is insufficient to rescue the highlight, though pyro makes them retrievable using a supplementary film mask. (Generally
I prefer straight-line films like the 200's or now 400TMY, which are easier to print).
But I did conjure up a pyro tweak for HP5 which wonderfully prints off the stain only, with no visible silver image! Just blue light vs stain, but this works only with HP5,
so this tells me there's something unique about this emulsion. Too bad Super XX isn't
still around to make a comparison. But I'm beginning to suspect that HP5plus has
undergone subtle reformulation in recent years that we're not informed of. And I have no idea if there's any truth to rumors of developer-incorporation in certain
Ilford films.

Kirk Keyes
11-Mar-2011, 13:48
Drew - what do you use for the afterbath - the spent developer or some other solution?

Drew Wiley
11-Mar-2011, 16:05
Afterbath - sometimes the sheets just go back into the used PMK developer, sometimes into a separate tray of metaborate. Doesn't seem to make much difference.
Just an alkaline environment.

Kirk Gittings
11-Mar-2011, 16:18
My understanding was that this second bath just raised FB+F and did not really contribute to usable stain and that GH himself no longer favored this second bath? Not first hand knowledge-just something I vaguely remember from a couple of years ago.

Drew Wiley
11-Mar-2011, 16:29
Depends, Kirk. GH's more recent tweak of PMK (Pyro Max) and omitting the afterbath
was an attempt to make HP5 more printable on both conventional VC papers and Azo
or other contact processes. It does this as a kind of compromise. (I won't get into this
tweak vs. pyrocat formulas or w2d2+ strategy etc. When I contact I prefer high-end
VC papers anyway, mainly for the way they tone.) With HP5 and FP4 an afterbath can
indeed overdo the stain. But with TMX and tabular grain films, an extended afterbath allows fine-tuning of the highlights, and I don't see any evidence of across-the-board neutral density - it seems selective. In other words, what is true in one set of circumstances does not warrant a generalization with all types of film.

Kirk Keyes
11-Mar-2011, 16:49
My understanding was that this second bath just raised FB+F and did not really contribute to usable stain

This has been my observation using used developer.

Any staining in a used developer should be non-selective as there is no development occurring at that point, as all the undeveloped silver halide should have been removed at this point.

Jay DeFehr
11-Mar-2011, 16:51
Drew,

Every time I've measured stained step wedges that have been treated with an after bath, any increase in stain is in general stain, not proportional stain. In other words, if the stain increases by 0.15 on the dense end of the wedge, it also increases by the same amount on the thin end. This is using the spent developer. A plain alkali bath adds no stain whatsoever over simply soaking in water for the same length of time.

frotog
11-Mar-2011, 16:55
PMK is extremely sensitive to oxidation which leads to chemical fogging ...read high base fog densities and ugly tonality. Some years back I incorporated nitrogen gas into my process, both in a jobo and in inversion tanks. The base fog all but disappeared and the color of the stain on the neg changed from a yellowish green to an amber. The negs print much better too. If the dev. comes out the same color as it went in, you're in good shape. If it's very much darker then it's oxidized.

The alkali after-bath was Hutchings' original suggestion back when he first printed his how-to book on PMK in the late eighties (was it really that long ago?) and of course everyone, including myself, followed suit. While you are increasing the stain on the negative it is a general, overall increase effecting the less dense areas just as much as the areas of greater density. This has the effect of simply increasing your b+ f density effectively flattening out your mid-tones and making it increasingly more difficult to print for black. It's really not at all a surprise that once the mid-nineties rolled around Mr. Hutchings changed his mind on the whole extra-stain/afterbath thing. So some of that stain that you are seeing might be the result of an overall oxidation/chemical fogging which, yeah, I guess makes your highlights brighter.;)

Drew Wiley
11-Mar-2011, 17:28
If you had been paying attention to my diatribe, I already mentioned something which
defintively gives evidence that the stain is not just added overall density due to aerial
oxidation. Namely, I made a tweak to PMK with afterbath included in which there is no
visible silver image - in other words, put the developed HP5 neg over a lightbox and you see almost nothing unless viewing thru a deep blue filter (and printing with one
onto VC or very hard graded paper). The prints have exceptional crisp scale, and were
therefore printed off PROPORTIONAL yellow stain. Whether the current HP5 will act
in the same manner I don't know. And I couldn't get this tweak to work with any other
film. But even with other films like T-grain, you can judge the effect thru a blue filter
respecting microdensity, edge effect, what is and is not proportionately stained.
You're telling me that elephants don't exist when I've got them roaming the darkroom on a routine basis. Maybe you're confusing this kind of stain with fog from aerial oxidation. I'm well aware of what happens with PMK in a rotating drum and don't use one for this kind of developer. My negs tend to have relatively clear margins.

Jay DeFehr
11-Mar-2011, 17:48
Drew,

PMK definitely produces proportional stain, but the after bath does not. Many have bleached out the silver from stained negatives and printed the stain image. I've done it with many different films. It's more useful for scanning than printing, in my opinion, and even there, the combined silver/stain image is more practical and flexible.

sanking
11-Mar-2011, 18:39
Drew,

PMK definitely produces proportional stain, but the after bath does not. Many have bleached out the silver from stained negatives and printed the stain image. I've done it with many different films. It's more useful for scanning than printing, in my opinion, and even there, the combined silver/stain image is more practical and flexible.


I totally agree with Jay on this. The after bath produces nothing but general (base+fog) stain. Like Jay I have tested this with both Visual, Blue and UV light with numerous films. The general stain contributes nothing to image formation, and nothing to overall density range or CI, but it does add extra density, which will increase printing time slightly.

The only possible positive benefit to the after bath might be a reduction in the appearance of grain.

As others have pointed out, the after bath procedure was recommended in Gordon Hutchings book, but my understanding is that he has since changed his mind and no longer recommends this practice. I have never recommended the after bath with either Pyrocat or with any other pyro staining developer. I am 99.99% convinced that it offers no benefit whatsoever to printing, whether it be VC silver, graded silver or alternative printing, with the possible exception of finer grain, and I am not convinced of even this.

Sandy King

Drew Wiley
11-Mar-2011, 19:25
I'm just not getting that impression of fog in the shadow areas. It seems more like
selenium enhancement on thin-emulsion films (different printing effect, of course, which is the whole point). I was going to ask about bleaching tests, which thank you for anticipating. But my HP5 tweak involved no bleaching whatsoever. Just did some
comparison dev with Bergger 200 w/o afterbath, but haven't printed any of it yet.
I've used PMK with just about every film out there except TriX, and do notice with
respect to this question a real difference between thicker emulsion behaving films
(like HP5 and Super-XX, which base stain relatively easily), and thin fine-grained films which seem to need the afterbath to get good highlt stain and differentiation
from the shadows. I'm obviously a bit skeptical that all the variables have been
successfully covered by the usual suspects. As they say, maybe it's phases of the
moon ...

Drew Wiley
11-Mar-2011, 20:33
Guess I'll have to run a battery of tests to isolate this question a bit more. Should be
pretty easy to do, but from a practical standpoint, relatively academic, because I'm
getting exactly the kinds of negatives I want. (More of a challenge to go back to the
early negs and reprint them.) In other words, low priority. (I'm trying to transition into color work for the season.) But I'll get to it sooner or later. I went back to HP5
briefly when Bergger 200 got discontinued, just to learn some new tweaks. But now
that I've thawed some more Bergger and stuffed the freezer with TMY, it's unlikely
I'll shoot any more HP5. Have plenty of FP4 on hand, however.

Kirk Keyes
11-Mar-2011, 22:54
If I understand you correctly, you say you are not bleaching the silver out of your negs for your stain-only negs. Would you care to share with us exactly what you are doing - some of use would probably like to give it a try.

Drew Wiley
12-Mar-2011, 10:16
Kirk - it was based on very dilute tray development 1:1 A/B ratios (rather than 1:2) and then distinct afterbath. But I don't know if the current HP5 behaves exactly the same way. It was HP5 "plus"but I suspect some sort of subtle emulsion difference. My cold light has a lot of punch so will easily handle printing through a deep blue tricolor (47B) filter. When I tried this with other films I got a marginally detectable image using blue light, but with too much fog and too little density to print. And unfortunately I didn't have any Super-XX left to compare results with it. My head tells me that the guys are right when they say the afterbath only adds neutral density, but my practical experience in the dkrm looking at the various negs and seeing how they print tells me there might be something about this which is still an open question.

Kirk Keyes
12-Mar-2011, 15:31
Well, chemistry tells us that an afterbath can ONLY add an overall stain. There must be exposed, undeveloped silver halide to make stain proportional to the exposure, through the action of developing those exposed, undeveloped silver halides.

I'm still a bit confused about the silverless, blue exposure subject. So there is a silver image in the negs you were printing, and you were just using an all blue exposure that produced acceptable prints when using HP5+ but not your other test films, right?

Drew Wiley
13-Mar-2011, 16:34
The question is whether some other variable has not been accounted for. I run into
this kind of stuff all the time with DT printing, where decades of testing has the former trade well informed of what is and is not possible, then someone breaks these rules and it works, and can be pretty difficult to explain why - kinda like color Daguerrotypes which no one can figure out wihout destroying those rarest of images. With something like HP5 I'd be asking whether there was a change at some
point in the gelatin. Pyro tans, so it is possible there might have been a change in
susceptibility to afterstain, based upon relative hardness of the gelatin, hence the
possibility of proportionality under certain circumstances. Just a wild hunch. But the current batches of this film don't seem to give the same degree of edge effect as the earlier batches, and there are other subtle differences which make me wonder. I could be totally wrong of course, but at the moment don't personally have a better explanation.