What's special about two-emulsion (not x-ray) films?

Bill Burk · Mar 23, 2023

I am chatting on a Facebook group with someone who wants a replacement for Plus-X in 35mm, 120 and 8x10

It’s a two-emulsion film she’s looking for. And I hate to admit I didn’t know what she was talking about until she showed some pictures that illustrate… sure enough there’s two layers…

To quote @DREW WILEY from a recent thread…

—
No thick-emulsion, very long straight line film equivalent to Super-XX now exists. Bergger 200 was the last semi-equivalent. The present Foma/Arista pseudo-200 has a long straight line, but none of the other desirable characteristics. TMax 400 is a reasonable substitute, but not the same thing either. FP4 won't handle anywhere near the same luminance range as the true 200's, though it's an excellent film in its own right.
—

So I looked around and found there isn’t a thread about two emulsion films and thought it would be a good question to pose.

What films are, or were in this class. What made them special. What substitutes exist.

And should I buy Plus-X now while I can?

abruzzi · Mar 23, 2023

I know little to nothing about it, but I belive the Bergger Pancro 400 was also advertised as dual emulsion. My understanding was it was intended to give a wider range of speed?

Andrew O'Neill · Mar 23, 2023

Aren't there several films that are duo emulsion? HP5, for example.

DREW WILEY · Mar 23, 2023

"Thick emulsion" and dual emulsion do NOT imply the same thing. Even especially thin emulsions like Fuji Acros can be dual ingredient. Color films have multiple layers, yet are all relatively thin. The fact nobody even seems to understand this distinction tells us how all thick emulsion films are now extinct. There were certain development tricks one could do with old Super XX that are unrealistic with any current film, which certain old timers lamented the loss of. Thick emulsions absorbed and retained solutions somewhat differently than thin emulsion equivalents. T-grain technology spelled their demise.

Bill Burk · Mar 23, 2023

@DREW WILEY Can you mention the development tricks? I imagine water bath with the idea that you dip film quickly in developer then put it in water so developer wouldn’t reach the lower layer (because you only give the film a laminar layer of developer)?

MattKing · Mar 23, 2023

If only PE was still here.
With black and white film, I don't believe that there are separate layers (of light sensitive components) - the two or more components are intermixed.
There are top coats and under coats that perform other functions.
The old thick emulsion films were that way because the tool for sensitizing emulsions were less effective and efficient, so you needed more light sensitive silver halide to accomplish the same film speed.

DREW WILEY · Mar 23, 2023

Yes, water bath dev was one of them. Divided dev also worked a lot better with thick emulsion films. My brother had a fun trick
where he'd pass a sheet of Super XX back and forth between a tray of hot developer and one containing cold developer, to deliberately reticulate the emulsion into an alligator-skin or mud-crack reticulated pattern. But this had nothing to do with a lower versus upper layer. It relied upon the greater thickness of the single emulsion coating itself.

gorbas · Mar 23, 2023

ORWO NP-7 high speed BW movie negative film had it some 30-40+ years ago. A few years ago I think I saw it on then their current film N-74 and most likely it's on their newest N-75 emulsion too? In a few week I will be developing that film and can check it.

Mick Fagan · Mar 23, 2023

I've been using Berrger Pan 400 since around 2015, this was one of the times I used it over my personal preference film, which is Ilford FP4+.

The shadow detail one is able to get without losing highlight detail is astounding, it was touted as a genuine two emulsion film, my experience with it is that it really is a two emulsion film.

This is a stock race on an old station in outback Australia, now a national park. Being backlit and also holding detail in the shadows was going to be problematic, so I used Berrger pan 400 and also used a sheet of FP4+, which by comparison, was not in the same league. I have used Berrger pan 400 for times when detail over a wide shadow to highlight range is required; it really works.

sasah zib · Mar 24, 2023

Bill Burk said:
I am chatting on a Facebook group with someone who wants a replacement for Plus-X in 35mm, 120 and 8x10

It’s a two-emulsion film she’s looking for. And I hate to admit I didn’t know what she was talking about until she showed some pictures that illustrate… sure enough there’s two layers…

.....

What films are, or were in this class. What made them special. What substitutes exist.

And should I buy Plus-X now while I can?

Plus-X was a great lab tool for doing split-seps for Kodachrome.. the K-11 & K-12 versions. Unless you or they are doing estate or archive separations ... I know of 2 people doing just that; they use Ilford PanF and FP4+

Plus-X and Ektapan were General Purpose Films drafted as lab films for their relationship to existing Kodak processes. For separations, prior gens of GPFs were much better. All of the big, 4 shift labs used lab-films for lab work.

[if you wanted specifics ... PMs work, if I'm around]

sasah zib · Mar 24, 2023

MattKing said:
If only PE was still here.
With black and white film, I don't believe that there are separate layers (of light sensitive components) - the two or more components are intermixed.
There are top coats and under coats that perform other functions.
The old thick emulsion films were that way because the tool for sensitizing emulsions were less effective and efficient, so you needed more light sensitive silver halide to accomplish the same film speed.

Gone, but some of his words remain.

There are a host of additional answers as well including hardener, synthetic substitutes for gelatin, and chemicals that can no longer be used in film, but which lent a particular 'character' to the image tone or whatever (in the eyes of the beholder).

In any event, the old emulsions were not robust, hard to make, used toxic chemistry such as mercury and cadmium and the new ones eliminated the mercury and cadmium and changed over to a new hardener from the old standby, formaldehyde. They are made by a new automated process that allows much more repeatability from batch to batch for better uniformity.

You may like or hate the new films, but environmentally they are so much more benign to manufacture and coat. As for tonality, they were designed from the start to give that long straight characteristic curve so that the photographer had more latitude to shoot with and got better pictures, but again, the acceptability of a given product is not a given. This is in the eye of the user.

Ron Mowrey :: December, 2005

Bill Burk · Mar 24, 2023

sasah zib said:
Plus-X was a great lab tool for doing split-seps for Kodachrome.. the K-11 & K-12 versions. Unless you or they are doing estate or archive separations ... I know of 2 people doing just that; they use Ilford PanF and FP4+

That’s one thing I figured. I know there’s a sharp fall-off in red and a bit of dip in blue for TMY2. (I adjusted and tested an infrared scope so safe for fifteen minutes), and I can skip the yellow filter (light clouds in blue sky show up).

So I figure the different “panchromatic” classes would be significant for color separations.

As far as I am concerned TMY2 and TMAX100 are sweet because they’re a stop faster for the same graininess (compared to vintage Panatomic-X and current Double-X 5222 respectively). And another stop faster when you don’t need a yellow filter.

But I sometimes find the TMAX T-grain unpleasant. A word that comes to mind is choppy. This is in 35mm (no big deal by the time I move up in size, completely a non-issue in 4x5 to me).

MattKing · Mar 24, 2023

The following is courtesy of a contact in the film business.
Essentially, all black and white films since the very early days of film manufacture are “two-emulsion”, or more, films. In order to obtain films with speeds fast enough for indoor photography, films required multiple sized grains and for a film to become panchromatic, that meant that grains of different sizes would require dying to record red, green or blue light. Each of those dyed grain “sets”, in their own emulsion could then be mixed into one large emulsion to coat or split up to coat in several layers.
Another means of making a “two-emulsion” black and white film would be to split the grain sizes into small to mid-sized and mid-sized to large each set to its own emulsion, and mixing all three dyed silver grains together for a slow-to-mid and a mid-to-fast emulsion. All panchromatic black and white films manufactured for still film photography have been manufactured like this for a very long time, perhaps 40 years or more.
Why?
Separating the grain sizes gives the advantage for the film manufacture to better control the film speed when the emulsions are made, and also when they are coated. Light absorbing dyes can be added to optimize a specific region of the DlogE curve’s speed by dying the specific emulsion, which will lead to better consistency and linearity in the product. These are tools that the manufacturer would not have if all the speeds were coated “all as one”.

Whether or not the numerous emulsion components are mixed together and coated all at once or coated separately in different layers depends on issues like viscosity and surface tension. So, for example, you might have:

Slot 5 - Overcoat
Slot 4 - “Fast” emulsion \___ because these layers have the same viscosity and surface tension, they tend to intermix on the hopper slide and curtain
Slot 3 - “Fast” emulsion /
Slot 2 - Slow emulsion \___ because these layers have the same viscosity and surface tension, they tend to intermix on the hopper slide and curtain
Slot 1 - Slow emulsion /
Support:

The result will appear like this:

-- Overcoat---
Fast Emulsion
Slow Emulsion
----Base------

DREW WILEY · Mar 24, 2023

TMX100 is the only film ever, I believe, where all three color separations can be developed together the same amount of time and achieve matching contrast, There's a learning curve to that, of course. I can't imagine using long-toe Plus X for separation work, especially with respect to Kodachrome. Never heard of that one before. Pan F???? - even less realistic.

The spectral sensitivity of TMX was deliberately engineered with color separations in mind, as a replacement for Super-XX, but even more responsive, and without its annoying graininess.

What developer are you using for TMax films, Bill? My gripe with TMX100 is that the grain was too fine, and I wasn't getting enough edge effect. I finally solved that by using Perceptol 1:3, and it gives an approximation to the TMY400 look, with just a little less graininess. It important to me in 120 roll film work. With sheet film, might as well go directly to the 400 speed product, but not for color sep work.

Bill Burk · Mar 24, 2023

I threw “color separation” into the discussion because I knew that’s a critical application where you need to rely on the spectral response and the long straight line. I figured that was what you looked for in a film @DREW WILEY . Though I might throw a set of color sep filters on a camera for a project, I don’t regularly do it.

The person I was chatting with was talking about portraiture and double tonal scale and specks of sparkling highlights. Some mystical qualities that I have heard before but don’t know what they mean in terms of characteristic curves.

Bill Burk · Mar 24, 2023

Oh and I use D-76 1:1 for practically everything.

DREW WILEY · Mar 24, 2023

Well, Plus-X was targeted to the studio portraiture market due to its ability to separate midtone and highlight value so well, but at the expense of deep shadows. That was back when "skintones" predominantly meant Caucasian skin values. With mixed ethnicity group portraiture, or darker complexions in particular, I preferred TMax. But depending on how you develop it, Tmax can mimic several past films. And that's what Kodak hand in mind.

takilmaboxer · Mar 25, 2023

For many years my favorite film was Verichrome Pan. It was an old school two emulsion film. Alas, it's long gone.
There was a time when Kodak made Plus-X Pan and Plus-X Pan Professional. The former had a short toe, the latter a long toe for studio use. I seem to remember that Tri-X was also made in the same two types.
And to add confusion, there was a time when Verichrome Pan and Plus-X Pan were the same emulsion but Plus-X had retouching surfaces on both sides.

Bill Burk · Mar 25, 2023

DREW WILEY said:
Well, Plus-X was targeted to the studio portraiture market due to its ability to separate midtone and highlight value so well, but at the expense of deep shadows.

This is what I think my correspondent was thinking. What does this mean In sensitometric terms though?

I have not seen curves that do anything magical.

The three curves I have seen are:

1: Short toe, long straight line (TMAX100 and TMY2)

2: Long toe, long straight line (HP5+, Tri-X)

3: Long toe, early shoulder (Double-X 5222)

When superimposed on print paper’s strong s-curve, there’s not much difference in the results. There’s less difference in the prints if the film is given enough exposure to get on the straight line but not grossly overexposing.

DREW WILEY · Mar 25, 2023

Gotta disagree with you 1000%, Bill; and I have very good reasons.

There are significant practical implications to what at first glance might seem to be only minor differences to characteristic curves to an untrained observer. The thought of using Plus X is a high contrast desert or mountain glacier scene would be preposterous. It was designed as an "all toe" film with high key studio portraiture in mind. Super XX was the "straight line" commercial film of that era, capable of handling serious contrast well; and Tri-X was the middle-of-the road option, popular for journalism. In the photo academy, the students, including my older brother, were expected to understand these basic differences, and had to master all three films, or else the inability to do so would probably end their career before it even began.

Today, even the lesser distinction between a straight line which goes well down into the shadow, like TMax films do, and a more generally film like FP4, can easily make or break what I myself routinely encounter in high contrast situation outdoors. Boosting the exposure up onto the straight line of FP4 or Acros by rating these at 50 instead of 100 helps, but still doesn't make them equal to TMax. I now avoid HP5 for high contrast settings, unless I'm willing to mask it afterwards. And I have a LOT of experience with all these films and numerous other ones too, including in 8X10 format where it gets really cumbersome and expensive if a film is less than ideal to the situation. An OK print and a classic one are a world apart in my dictionary.

Bill Burk · Mar 25, 2023

Do you disagree with me regarding whether or not slight curve shape differences are magical?

Or are you disagreeing with the classifications I mentioned?

I’ve been in the high mountains and clung to the trunk of a snag so I could lean over a cliff above fish creek and when I metered the scene afterwards I found the scene had a five stops subject luminance range.

I haven’t seen a 12 stop range since that time I hung out with rattlers in the shade while boulder hopping in Joshua Tree when I was in high school.

@RalphLambrecht gives a convincing demonstration of the difference between placing an exposure on the toe versus on the straight line. His photo of a bench under a staircase reveals a more inviting place to sit when you use the toe right.

But I would like to see more examples.

It’s got some mystical qualites. I have two prints that I swore were either 4x5 or Panatomic-X that turned out to be Plus-X when I found the negatives.

This is one of them…

takilmaboxer · Mar 25, 2023

The data sheet for Adox CHS 100-II clearly states that is a two emulsion film, giving the reason as "increased exposure latitude." Have you tried that one?

john_s · Mar 25, 2023

On the subject of multiple layers, maybe this is of interest. It's from the Crawley article from BJP around the time that Delta400 was upgraded (maybe early 2000's?)

<start quote>
With the launch of Delta 3200 last year, Ilford came up with a
solution to the problem, evolved from 100 Delta. The same
principle is applied in the new Delta 400 reviewed here. In fact it
harks back to traditional know-how but in an updated guise. Delta
3200 is a bi-pack, and each of the two layers is made up of two
emulsions, four in all, of which three are new. The high-tech
halide crystals have a silver iodide rich core around which is the
bromide shell and sensitisers. The interfacing of the iodide rich
core with the bromide shell creates a larger number of possible
latent image centres in the shell to trap the incident light. So there
is enhanced sensitivity and pushability.
The new Delta 400 is also a twin-layer or bi-pack, but with only
one emulsion in each layer. The top layer has the medium speed
emulsion from Delta 3200 and the bottom layer has its slow
component – itself in fact the fast component emulsion from 100
Delta. Light that over-exposes the faster top layer is accurately
recorded by he slower bottom layer. The result, as with bi-packs
of long, long ago, is exposure latitude and pushability.

MTGseattle · Mar 25, 2023

Here is a copy/paste direct from the Adox (English) website;

ADOX CHS 100 II is an orthopanchromatically sensitized B/W film with classical grain and a sensitization optimized for greyscale separation.
The film is made from two separate emulsions in a single layer coating and yields a very large exposure latitude.
Due to its classic sensitization it features a very harmonic tonal separation.
Compared to modern films it differentiates better between lips/face, clouds/sky, water/land.
The film is coated onto clear archival PET.

ADOX CHS 100 II and can be reversal processed (including the sheetfilms).
Due to the backside Layer the sheetfilms are retouchable with photo dyes.

In the 35mm and 120 format ADOX CHS100 II has two anti halation layers.

• Between the emulsion and the base (AHU)
• On the backside layer (anti halation, anti lightpiping and non curling)

Due to the extra AHU layer in the miniature and 120 format there are slight differences in the developing times between those films and the ADOX CHS 100 II sheetfilm.
In order to achive a medium contrast of 0,65 reduce the sheetfilm developing times by about 10%.

Films coated onto PET are subject to the lightpiping effect and must be loaded in the shade.

Rollfilms tend to spring open so they need to be held even more tightly than triacetate films when loading into the camera.

Tanning developers (Pyrogallol / Brentkatechin) are not recomended for Films with an AHU as they can cause tiny emulsion liftoffs.

MTGseattle · Mar 25, 2023

@Bill Burk do you have that above picture mounted in an old window sash?

What's special about two-emulsion (not x-ray) films?

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