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Fragomeni
01-22-2011, 01:54 PM
I am developing a new workflow for in-camera processes. This will serve as a replacement for older paper negative processes that are now difficult to get materials for. I am primarily interested in coating paper and acetate (or other transparent substrates) with a fixed grade (I understand some variance is present) liquid emulsion. The big obvious problem that comes up is that the liquid emulsions available are not panchromatic. I have read most of the posts here on making these emulsions panchromatic but I am not clear as to how exactly to do it. I am not a chemist and I would like to be able to develop a workflow that will allow me to get back to my photographic work without forcing me to become overly concerned with chemistry and complicated lab work. Can anyone describe in laymen's terms if and how I can make a commercially available liquid emulsion like Liquid Light or Ag-Plus (I think this is preferred for my purposes because of the increased sensitivity) panchromatic? If there is anyone who has successfully done this can you please share your workflow in a step-by-step manner and provide sources for your materials.

I would very much appreciate any help with this and I apologize if any information will be repeated from other posts.

To clarify, my intention is to coat paper and clear substrates with an ideally panchromatic emulsion to be exposed in camera and then contact printed. I have a 20x24 with which this will be used and I will be coating papers and substrates in varying sizes that fit within 20x24 inches.

Photo Engineer
01-22-2011, 02:20 PM
Francesco;

The SRAD (Single Run Ammonia Digest) emulsion that I posted here has been repeated by others with varying degrees of success. Basically though it can give a speed of about ISO 25 - 80, average of 40 with good lab technique. By adding a green and a red sensitizing dye, you get a pan emulsion. Green sensitizing dyes are easy to get. Red sensitizing dyes are harder to get. I have one dye that I posted here which gives me Red sensitivity with Br/I emulsions but others have not been able to get it to work.

If it does work, you need to carry out all work in total darkness or IR.

In addition, you need a source of subbed support for film coatings or you are locked into plate coatings more or less.

With most dyes, the procedure is to make the emulsion up to the point of coating but before adding the surfactant and hardener. At this point add the sensitizing dye(s) and hold at 100 - 115 deg F for 15 minutes. Then add the surfactant and the hardener and coat. You may have to split the emulsion into 2 parts, one red and one green as the dyes often interfere with each other, or you may have to get one broad dye to do combined work as red and green.

The problem is that the exact quantity of dye to be used is critical and must be determined by trial and error with each emulsion. I generally use about 50 - 100 mg of dye/Mole of Silver. If you use too much or too little you don't get the desired speed. You also have to have a method to measure the sensitivity to check out if it worked.

PE

Fragomeni
01-22-2011, 02:29 PM
To your knowledge is it possible to do this with the commercially available liquid emulsions? To my knowledge (limited), all you do with Liquid Light and Ag-Plus is put it in a hot water bath to bring it from the gel state to a liquid and then you coat your substrate. I would assume that to mean that there is no surfactant or hardener in the coating process for these products. I guess I'm wondering if there is a broad dye that can be added directly to the heated liquid emulsion? What methods are there to check it you have the right amount of dye(s)?

Fragomeni
01-22-2011, 02:30 PM
Also, is there a US-based source for these dyes where I can buy them?

Fragomeni
01-22-2011, 02:36 PM
The way I'm thinking about it (probably very idealistic), if there is a mixture and method that I can use to mix batches of Ag-Plus with a red/green sensitizer to make it panchromatic then I would be able to mix batches and test the exposure iso for each batch (because each batch differs slightly) and dial in the necessary amount of red/green sensitizer. I'm trying to find the least complicated method of achieving a panchromatic emulsion. I guess it would be safe to assume that there is no method that isn't complicated to some degree but if there is a method that I can use which involves the least number of steps and is based solely on mixing readily available materials and based on some method of effectively testing sensitivity then that would be ideal and likely have a learning curve that I can handle.

Photo Engineer
01-22-2011, 02:40 PM
Sands corporation in Florida is the only US source that I know of at present. They were not able to supply me with a red sensitizer that works reliably. Figure $100 / gram for the dyes.

IDK about the Liquid Light or any other product. You would have to test them.

PE

Fragomeni
01-22-2011, 02:43 PM
Ok, thanks very much for your help PE! Glad to have you around!

Anyone else out there have direct experience with Liquid Light or Ag-Plus and making these panchromatic? I can most likely use these very effectively as is to make paper negatives to obviously a panchromatic emulsion would make for the best negative.

JessicaDittmer
03-27-2012, 09:52 AM
Did you end up trying this? I'm looking at the Ag-Plus online thinking about if it can be put on glass to make negs in my 8x10 camera? Please share info you've found/tried if you can. I would appreciate hearing how it went. thanks!

jnanian
03-27-2012, 10:01 AM
Did you end up trying this? I'm looking at the Ag-Plus online thinking about if it can be put on glass to make negs in my 8x10 camera? Please share info you've found/tried if you can. I would appreciate hearing how it went. thanks!

hi jessica
it is not difficult to coat glass with liquid emulsions, any of the ones you buy in a store or online
can be used to coat glass, but they will not be panchromatic emulsions, only like paper emulsion ( blue sensitive )
if you can get your hands on a book called silver gelatin: a user's guide to using liquid photographic emulsion ... you won't be sorry.
i taught myself this craft before books like that were around, and the internet wasn't around and .. it was a lot of trial and error.
basically you need to chemically clean your glass plates, and then sub them ( if you want ) with gelatin or another material that will stick to the glass
and allow the emulsion to anchor to it. some have success without the sub layer ( i never have ) ... then you coat the plate ...

http://www.alternativephotography.com/wp/processes/gelatin-silver/silver-gelatin-dry-plate-process
gives a great demo.

good luck, and have fun !
john

JessicaDittmer
03-27-2012, 11:46 AM
thanks! I'll check out the link and look for that book!-j

wildbillbugman
03-27-2012, 02:35 PM
PE,
In view of my recent results with my panchro emulsion, Could people add some ammonium iodide to commercial blue sensitive liqid emulsions , then add a green sensitizer(picking which one would be the trick) and thereby make a red and green sensitive emulsion.
Bill

Photo Engineer
03-27-2012, 02:59 PM
IDK Bill, but Ammonium Iodide causes more fog (in general) than Potassium Iodide.

PE

jnanian
03-27-2012, 04:09 PM
thanks! I'll check out the link and look for that book!-j

oh, and i forgot probably one of the best places to hang out would be thelightfarm.com
tons of info, recipes and good folk :)

john

Photo Engineer
03-27-2012, 04:33 PM
Adding to my last post, I have checked and Ammonium Iodide is not all that stable. It decomposes into Iodine and various Iodine salts such as Iodates. So, KI is the only Iodide salt I would suggest using.

PE

wildbillbugman
03-27-2012, 05:19 PM
Thanks PE,
I started using NH4I back befor I got a handle on Alcohol precipitation as a means by which to wash a PVA based emulsion. I was trying to minimize the content of materials that needed to be washed from the emulsion. So I used NH4Br as well as NH4I. Now that I have come to trust alcohol presipitation I should be able to switch back to KI. What about KBr vs. NH4Br, aside from adjusting for M.W? Bill

Photo Engineer
03-27-2012, 06:16 PM
Bill;

The only two salts that have low stability in that series (that I could find) are NH4I and NaI. These decompose. All others are reasonably stable.

PE

Photo Engineer
03-28-2012, 10:30 AM
Color negative papers such as Endura or CA must be shot with a heavy red filtration and assuming an ISO value of around 25 after filtration. The estimated process is: 1st developer (D-19 1:2 or 1:3) 2', stop 30", wash 30", re-expose, CD 2' (RA-RT color developer or equivalent), wash 30", Blix 2', wash 2' or longer and all at 68 deg F (20 deg C).

PE

Photo Engineer
03-28-2012, 10:09 PM
The silver image in color papers is extremely weak. Do not rely on it for imaging.

PE

VesaL
09-08-2013, 11:53 AM
This is an older thear that has not been commented awhile. I am trying to make a commercial multicontrast liquid emulsion panchromatic. If i have correcty understood or totally misunderstood, variable contrast emulsion/paper should be somewhat sensitive to green light..?


Using methyl violet (i currently cannot obtain ethyl variant) There is a slight possibility to extend the sensitivity little bit towards red.

Photo Engineer
09-08-2013, 11:58 AM
VC papers are sensitive to blue and green light. The two emulsions have different contrasts and when the color of the exposing light varies, the exposure to these two emulsions varies giving variable contrast. If you try to use this as a pan emulsion, it will work, but the contrast will vary according to the exposing light.

It would give an odd image.

PE