11/1/25-12/1/25:  BASIC ADHESION - FIRST TESTS - Peter Renn

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Jacro make no claims for this material except to describe it as "subbed".  This I take to mean the acetate base has been chemically treated to allow other materials to stick to it much like the "subbing solution" sometimes used with things like liquid emulsions or the surface preparations on inkjet transparency materials. 

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TEST A: - Can I detect a subbing layer and if so, which side of the film is it?

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The subbbing layer cannot be seen with the naked eye. Both sides of the material look identical: glossy with a high acetate shine.

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A wet finger rubbed on the INNER* side of the film had a little more 'feel' and friction than the reverse, which felt totally smooth and slick when wet.

* The film is supplied on a roll. Much like traditional 35mmm the coated 'emulsion' side is on the inner side as rolled.

The lengths I've shared are rolled the same way.

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TESTS B- N: - Which common alternative process solutions will adhere to the subbed surface?

 

A fairly 'rough and ready' experiment, using whatever means was easiest to apply chemicals to the film pieces.

 

B: SILVERPRINT SE1 EMULSION

Applied with a small brush. It cooled on contact as the surface wasn't warmed. 

This adhered reasonably well, though of course the brush marks are very obvious. The coating is very thick a

nd crude as you'd expect with a cheap nasty nylon brush.

Not only did the emulsion stay on , it survived processing. D

eliberately fogged I gave it 2.5 minutes in 1:9 PQ Universal dev, 1 min in Kodak Indicator stop and 3 min in

1:4 tetanal superfix, followed by 10 min wash in running water. T

he darkroom was quite cold (15 deg. C) and the chemicals were all at a similar temperature.

The final wash was 9 deg. C. - Much colder than I would normally use but warm solutions tend to soften the

emulsion so I gave it the best chance I could.

NOTE: The Silverprint emulsion is quite old (It must be at least 2 years old) but it's been kept in the fridge and not used.

I've no fresh liquid emulsion in stock at present!

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The picture opposite shows the test piece after processing and drying.

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C: CYANOTYPE 

Normal cyanotype chemistry (parts A and B) as used for prints just applied directly to the surface. -

Not succesful but also not quite a total failure!

The solution didn't run or coat the surface at all well, beading up and mostly rolling off as if there was no subbing,

but I exposed the mess anyway with 10 min of UV  light and rinsed it. It darkened as expected and turned dark

blue on rinsing but most of the solution washed straight off. A small blue stain resisted washing for a couple of

minutes though so there may be potential for more experiments with cyanotype.

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The picture opposite shows the test piece after processing and drying.

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D: ARGYROTYPE

Much like C, I used straight Argyrotype chemistry straight from the bottle as used for prints.. - Not succesful.

As with the cyanotype, the solution didn't want to stay on the surface., lying in blobs or running straight off. 

10 min of UV  light made the dry solution darken but on rinsing virtually all of the solution washed straight off.

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The picture opposite shows the test piece after coating and drying but before any processing.  It's typical of  the

aqueous (water-based) solutions' behaviour. The droplets look wet but this was after it had dried. 

 

 

 

 

 

 

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E: SILVER NITRATE (10%) SOLUTION

I used a little of my collodion 'A' silver bath so it is iodised.  Coating was the same as the other aqueous solutions - i.e. not very good!  The same beading-up and rolling off the surface.  I will also try it added to the salt and gelatin solution-coated pieces to see if that works.

 

F: ALBUMEN (PRINT FORMULA)

The formula I use for albumen prints is:

72g powdered albumen dissolved in 473ml of distilled water

Add 2ml of citric acid and 15g of ammonium chloride, whip to a fine froth and cool overnight, then filter and store.

This stock solution was coated directly onto the film. -

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G: SALT (2%) SOLUTION

A very basic solution of 2g per 100ml distilled water used for preparing papers for salt printing.  The film was soaked in the solution for 3 minutes, Not surprisingly it behaved like all the other water-based solutions and fell off the surface.

 

H: SALT (2%) SOLUTION

Prepared identically to G.

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I, J,K,L,M,N: - GELATIN/SALT SOLUTION

A variation of salt printing is to make a gelatin-based sizing solution to help it stick. As this looked worth trying (even though it's sort of re-subbing the subbed film!) I made a batch of solution and coated five more pieces of film.

The gelatin /salt recipe is:

2g of powdered gelatin 'bloomed' in 200g of distilled water

bloomed gelatin and water added to 700ml more water with 20g of citric acid and 100ml of stock 2% salt solution (see G above)

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Thoughts so far...

Whtever the subbing layer on this stuff is, it 's not really up to making aqueous solutions stick directly. This isn't really surprising as actual film emulsion is gelatin-based (or something like it) so it's probably perfect for that but not really designed for other things.   It's always worth testing assumptions though so I tried anyway.   So far these results seem to confirm it.  The SE1 liquid emulsion (B) stuck pretty well - in much the same way as I'd expect it if subbed with a gelatin/alum solution as used traditionally for non-porus substrates like glass, ceramic or plastics.  Straight cyanotype chemistry doesn't stick to those materials very well even with a gelatin/alum sub but it can be made to with additional chemistry.

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I was hoping for a 'wonder-sub' coating whaih would allow anything to be applied to 35mm stock. This clearly isn't the case but it does show promise. There are plenty more solutions to try but research here needs to be on what would act as a practical subbing layer.

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I'll try some variations on the SE1 emulsion to see what can be achieved with more refined (less messy!) coating techniques and from there try some more DIY silver-gelatin emulsions.  I'm not a dry-plate expert at all so I hope those who are will achieve much more!

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13/1/25:  COATING LIQUID EMULSION ON JACRO FILM - Peter Renn

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As the liquid emulsion was by far the best at coating the film I tried a couple of strips with this.  I've only got some rather elderly Silverprint SE1 emulsion so it may well prove to be fogged to some degree. However even if it's no good it will do to test coating techniques and resistance to damage. - 35mm cameras are quite tough on the film: It gets pulled through a velvet light trap in the cassette, bent over rollers and pressed by a plate before (usually) being curled in the opposite direction on the take-up side. Much of this is then repeated as the film is rewound and then processed. - If it can survive all of that I'll be impressed!

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TEST P: - GLASS ROD COATING

Dry plates are generally coated by pouring, technique  similar to that used in wet plate.

This isn't really practical for such small negs on a floppy material like acetate. It's also harder

to remove excess solution.  I taped the film down to a sheet of plate glass with decorators' blue

masking tape, just covering the sprocket holes. This stops the solution from reaching the back.

A small glass rod 'puddle pusher' was used to spread the solution along the length of the film.

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I coated strips of about 50cm at a time as that's the size of my glass and also my drying box.

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It's not easy to see in the picture as the film is so clear but you should be able to see the 

outline of the tape edges under the blue tape and the end of the film at the bottom.

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The tape on the sides helps hold the rod at a fixed distance above the surface and should

give a good even coating. In practice it wasn't quite so easy. I needed a couple of passes to get 

a reasonably even coat and there were still places where it was too thin. I didn't persist as the

emulsion cools and starts to set very quickly and I know it gets horrible and lumpy and coat

quality just gets worse if you try for more.

I daresay my technique would improve if this proves to be the way to go.

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TESTS Q and R: F OAM BRUSH COATING

This was easier and under the safelight at least) seemed to give a more even coverage.  A couple of passes back and forth gave a pretty good-looking coat though it's hard to see oinholes or brush lines under the safelight. - a dark background would help.

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14/1/25:  EXPOSURE AND DEVELOPMENT OF LIQUID EMULSION

ON JACRO FILM - Peter Renn

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After air drying overnight (just in the drying box without the fan switched on) the test pieces P, Q and R were ready for testing.

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The emulsion side is very hard to identify as both sides look equally shiny. The film has no anti-halation backing either but is very clear. I suspect for single pieces it would expose perfectly well through the back (wrong side) but you wouldn't want to load a roll into a camera the wrong way up as the camera transport and pressure plate would most likely scratch it badly.  Leaving a little piece if the masking tape on the emulsion side can help. Also it seems to curl very slightly away from the emulsion, making the CONVEX surface the emulsion side.

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I started with pieces Q and R as they had the most consistent-looking coating.   I cut the film into individual pieces about 40mm long so as to expose a single frame at a time.

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Test camera was a cruddy old Zenit E. - I  didn't want to risk messing up a nice camera if all the emulsion flaked off inside!  As it happened it was fine.                    

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DEVELOPER
Liquid emulsion is usually treated like paper: Exposed under the enlarger or by contact and developed in paper-type developers.  Paper negs whether pinhole or plate camera/lens exposures need a less aggressive developer and I typically use  a film dev like Rodinal at a high dilution: 1:25 or even 1:100.  I decided to start with Rodinal at 1:50.

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TEST Q1:  BASIC DEV TIME   (not pictured)

I took a piece of film and let it fog completely by working with the white lights on in the darkroom.

DEv: 1:50 Rodinal (R050) - 2 minutes at 20 deg. C.

STOP: 1:19 Kodak Indicator stop (standard dilution) - 1 min

FIX: 1:4  FIX AG (Ammonium Thiosulphate print fix) - 2 min

WASH:  5-8 Min in running water (<10deg. C.)

This gave a reasonable -looking density without looking ultra-black. - roughly the kind of  D-Max you'd be happy with on a norlam film neg.

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TEST Q2:  EXPOSURE TEST  (not pictured)

I screwed this one up as I had forgotten this model Zenit is manual aperture only and so it exposed at f/2 and not f/11.  The film went black because I'd over-exposed massively - or maybe the emulsion was all fogged and no good?

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TEST Q3 - FOG TEST  (not pictured)

To ensure the emulsion wasn't fogged I tested an unexposed piece by processing it straight from the box.  It was fine - clear and not fogged. Camera or rather operator error was to blame for Q2. 

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TEST Q4. EXPOSURE TEST:  ISO 3  Rodinal 1:50 2 min

Rating the film at ISO 3 I gave it a 5 sec exposure at f/11. - and I was rewarded with an image! 

This view of Liss Mill from my house is my standard test subject as there's usualy a good

range of brightnesses from the skiy down to the dark hedge at the bottom. This exposure is

OK - but there;'s no detail in the shadows (metered at Zone III)  There's a blob (of thick emulsion?

over the top part of the building making it look blurred but there is detail. 

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TEST Q5.EXPOSURE TEST:  ISO 1.5  Rodinal 1:50 2 min (not pictured)

No image - Not sure why. 

I just re-tested with a fresh piece of film for test Q^ below

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TEST Q6.EXPOSURE / DEV TIME TEST:  ISO 1.5  Rodinal 1:50 (pulled*)

I broke a rule of testing here: I changed TWO variables (exposure and dev time) at the same time.

I could see an image after about 20 seconds so I pulled it from the developer early at 30 seconds

instead of 2 minutes. There's an image but it's very 'thin'

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TEST Q7.EXPOSURE TEST:  ISO 1.5  Rodinal 1:50  2 min

​Lesson learned, I re-tested, rating at ISO1.5 and gave the full 2 minutes dev time.

This has good shadow detail but the mid-tones and highlights are very flat.

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TEST Q8.DEV TIME TEST:  ISO 1.5  Rodinal 1:50  4 min (not pictured)

To see what effect the development time had I repeated Q7 but doubled the dev time to 4 minutes.

There's not much difference. The shadow detail is OK but the mid and high tones are still flat. 

Conclusion: extended dev time makes little difference. - but maybe  a stronger dev would be better

and perhaps there's a 'sweet spot' ideal dev time?

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TEST Q9:   DEV TIME TEST: Fogged film 1: 25 Rodinal 30 sec - 330 sec.  (not pictured)

I tried increasing the strength of the devloper to 1: 25 and experimented with dev times.

I fogged another piece of flim and developed it in stages, dipping a little in for 30 seconds, then dipping it

deeper for another 1 minute, then deeper for another minute, and so on until I had developed it for between

30 seconds and 330 seconds (5.5 min).

Conclusion: There doesn't seem to be much increase in D-max after 90 sec or so so I stuck with my 2 min dev

time for now.

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TEST Q10:   FAILED TEST.  (not pictured)

Accidentally fogged (operator error!)

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TEST Q11:   EXPOSURE TEST:   ISO 1.5  Rodinal 1:25  2 min

I suspected  the emulsion had very poor shadow detail and I was actually over-exposing: chasing

shadow detail at the expense of decent mid -rang exposure.

I switched subject as the sun had come out and the Mill was rather awkwardly side/back lit.

This is Ok but very contrasty: (contrasty subject admittedly but the shadows were measured on

Zone II and the bark highlights on Zone VII so not outrageous.

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This is the first picture which shows an interesting characteristic of the Jacro stock.  Unlike conventional film

It's perfectly clear, without the anti-halation backing normally added to prevent light passing through the emulsion

and bouncing back off the camera parts. This results in lots of flare in the highlights which is definitely something

to be explored.  It's easier to see in a positive print:

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TEST R12:   EXPOSURE TEST:   ISO 1.5  Rodinal 1: 50  2 min

Confirming this reasonably decent exposure /dev combination on another subject: this garden ornament. 

Here it is as a positive for a change.

Good (face placed on Zone VI but very dark shadows.

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TEST R13:   EXPOSURE TEST:   ISO 1.5  Rodinal 1: 50  2 min (not pictured)

Triyng a low-contrast scene to see if it can be rendered. The tree bark was placed on Zone V at ISO 1.5

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TEST R14:   EXPOSURE TEST:   ISO 10.75   Rodinal 1: 50  2 min

One stop more exposure so an effective ISO of 0.75. Again here it is a positive.

The vertical lines are coating defects - brush marks in other words!

The halation at the top of the picture is very noticeable. The strong light through the trees has gone through

the emulsion, bounced off the camera's pressure plate and come back through the film in a diffused

pattern.

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TEST R15:   EXPOSURE TEST:   ISO 1.5  Rodinal 1: 50  2 min

The brickwork was placed on Zone V at ISO o.75. The top of the building and sky were Zone VII - Zone IX

Again, the coating technique leaves a bit to be desired but the negative is sharp and printable. 

The difficulty is in predicting exactly how the material will react in terms of density and contrast. 

Much of this is down to coating thickness I think. - Dry plate people will no doubt be able to improve

on these very crude first results!

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TEST P - ROLL OF FILM - RANGE OF EXPOSURES.

This was piece P - the rod-coated section which I knew was unevenly coated and possibly partly fogged

(hanks to the cat!- don't ask :-). It's therefore very unscientific in terms of exposure and process testing but it was useful to test the feasibility of this as a 35mm rollfilm.

Liquid emulsion is generally pretty fragile so I had my doubts over how well it would survive being rolled up tightly, inserted into a cassette, transported through the camera

 (pulled by the sprockets, rubbed against the pressure plate, wound in the opposite direction etc.) and then handled for processing.  I used a re-useable cassette, shot it on the same horrible Zenit E and then processed it in a Kindermann metal spiral tank. - and it survived very well! No flaking, scratches or other physical damage I can see.

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