Emulsion Chefs Roundup

[Jerevan]

Yep, I still skulk around these corners too. Still read a lot. Been doing some walking the carpets trying to think up a scheme to get some sort of emulsion workshop going locally. Something as simple as possible to push a few other people over the edge.

 

[Athiril]

Bill, Athril indeed meant formate, as in Sodium Formate.

Ath: It's on my list but I haven't tried yet and I don't know that anyone else has either. There was a big discussion here a few years ago. I did get some formic acid but not Sodium Formate, which is what the patents call out.

Formate is supposed to produce two-electron sensitization.

-- Jason

Apart from the nature article mentioning research that used the formate ion for doping, there's other interesting patents that use formic acid in developer etc, which would produce the salt in developer, one calling it hypersensitisation of developer (the patent is expired too iirc), it uses formic acid, glycerine, some form of ammonia I think from memory, and an organic anti-foggant, in this case Kodak Anti-Fog #2 (the 6-nitrobenzimidazole iirc) at a low rate.

There are a number of patents and a lawsuit over this work. It was tried by Kodak based on the patents and we could not get it to work. In fact, AFAIK, no one but the original worker could get it to work. The rights were sold to Agfa (IIRC) and it was never commercialized in any product.

There is quite a bit of lingering controversy over this one and it is not just dump and stir. The Sodium Format is the Sodium salt of Formic Acid which is a close relative of Formaldehyde.

PE

There was a more recent research about it I think, and announced in Nature magazine, or was this in the same time period as that?

 

[Photo Engineer]

IDK, but AFAIK, all work on it has been stopped by everyone that had first shown an interest in it.

 

[Athiril]

Here is one from 1999 appears to be from Agfa
http://www.nature.com/articles/4722....com/news/1999/991223/full/news991223-12.html

And here's a Kodak patent filed a few years after the nature article from Agfa
http://www.google.com/patents/EP1271233A1?cl=en

 

[dwross]

Yep, I still skulk around these corners too. Still read a lot. Been doing some walking the carpets trying to think up a scheme to get some sort of emulsion workshop going locally. Something as simple as possible to push a few other people over the edge.

Hi! Great to know you are still skulking.

By "emulsion" I hope you mean silver gelatin. I'm afraid they don't get any simpler than three ingredients, plus water. To make a AgX emulsion you need silver nitrate(Ag), a halide(X), and gelatin. How about this one? http://www.thelightfarm.com/cgi-bin/htmltutgen.py?content=26Jan2013
There's more how-to on previous pages. I made some just last night. It goes together faster than supper!
Good luck with the workshop. Hope it runs.
d

 

[Photo Engineer]

You can get 3 contrast grades from similar formulas.

I suggest filtration through a gold coffee filter always be used, and that subsurface addition of the Silver Nitrate solution be used to prevent problems if you get bubbles from stirring.

PE

 

[Photo Engineer]

Here is one from 1999 appears to be from Agfa
http://www.nature.com/articles/4722....com/news/1999/991223/full/news991223-12.html

And here's a Kodak patent filed a few years after the nature article from Agfa
http://www.google.com/patents/EP1271233A1?cl=en

Thanks Dan, I read them both years ago and AAMOF know Jon quite well. So, the point is that R&D stopped for some reason. No commercialization took place and a bunch of lawsuits broke out.

IDK what went wrong, but I do know that the EK version of 2E sensitization was complete at the time of Jon's application, and he put it on a rigorous scientific basis, but it appears to be much more complex than the Kodak version. Two addenda and you are done!

PE

 

[NedL]

That is a very simple "recipe"! Is my guess correct that it would not stick well to glass because it is not washed?
PE: would the contrast grades be changed by how fast you add the silver nitrate?

 

[Photo Engineer]

Yes, it sticks to glass, but crystals form and ruin the image. You would use chrome alum to harden it and increase adhesion to the glass. Washing does not help this emulsion much but it can be done if you are careful.

Contrast does change a bit with addition times. There are better ways.

PE

 

[dwross]

That is a very simple "recipe"! Is my guess correct that it would not stick well to glass because it is not washed?
PE: would the contrast grades be changed by how fast you add the silver nitrate?

I think you're referring to the recipe I posted (??) It is a paper emulsion. So-called "gaslight" because it was/is slow enough to work by the light coming off a gas room light -- which was the lighting when this recipe was the latest-greatest . The contrast is quite flexible depending on the developer. It lets you have just one paper around at a time to handle a reasonable range of negatives.

If you are interested in a dry plate recipe that is almost as easy (although it includes by necessity a washing step) you might look at this one:http://www.thelightfarm.com/cgi-bin/htmltutgen.py?content=08Mar2013

 

[wildbillbugman]

kb3lms,
Sorry. I think that I am getting a bit too eager to chime in.

 

[NedL]

Thanks PE and Denise,

Yes I understood it was for paper, and like the old gaslight paper. I see that the formula you just linked to uses bromide and iodide, and that Kevin Klein's formula used KBr. But Chris Patton's formula just used a chloride ( or sea salt ), so I guess I was trying to understand how the simple chloride emulsion designed for paper differs from a simple one designed for glass. I was guessing that washing is the difference, but now I think there is probably something simple and fundamental that I am just missing!

 

[dwross]

In general, bromide emulsions are faster than chloride emulsions (they "see" just a tad bit more of the spectrum) and Br plus I are faster still, with a nice density range for a negative. Chloride emulsions are crisp and clean with deep blacks and bright whites (when exposed and developed correctly, of course.) A Br or BrI (without ammonia) dry plate is a perfect mate for gaslight chloride paper.

 

[kevin klein]

The simple bromide emulsion I use was modified from what was to be an unwashed paper emulsion, I took the trouble of filtering and washing because it will dry down to a very gritty surface on the plates but seems to still work fine. There is another emulsion that I found in a Lindsay Publications reprinted book on photography from the 1880's that is the same emulsion used for plates, the only deference is it calls for ammonia digesting the silver, filtering and washing. Ammonia, I can't stand working with that stuff.

 

[NedL]

Thanks! I know that mostly iodides and bromides were used to make calotypes, with chlorides used for salt prints. It seems like the same halides carried over to use in gelatin emulsions for glass and paper. Now I'm going to get sucked into this aren't I

 

[Photo Engineer]

And the problems with ammonia are why we are working on high speed non-ammonia emulsions at GEH.

At the present time, we are about ISO 50 and moving fast. I'm going to be at GEH on Friday to review results. It is difficult but Nick takes me over and pushes me around in a travel chair.

PE

 

[Hexavalent]

It's been quite a while since I've been at the emulsion cauldron -- the past year has been "busy" with challenges that have kept me away from the lab.
The last thing I was working on was a ISO 40ish ortho neg emulsion with a nice long curve. Hypo sensitized, with several additions of TAI throughout the to tame the rate of finish and ride the fine line between speed and fog.
I'm looking forward to going back into the lab once life settles down a bit.

 

[dwross]

Fingers crossed and best wishes, Ian. You are important to this game.

 

[dwross]

And the problems with ammonia are why we are working on high speed non-ammonia emulsions at GEH.

At the present time, we are about ISO 50 and moving fast. I'm going to be at GEH on Friday to review results. It is difficult but Nick takes me over and pushes me around in a travel chair.

PE

Your friends love you. For good reason. Good luck on the stink-less fast stuff!

 

[kb3lms]

I think that I am getting a bit too eager to chime in.

Bill, no problem. Did you ever find an economical red sensitive dye?

At the present time, we are about ISO 50 and moving fast. I'm going to be at GEH on Friday to review results.

Fantastic! Looking forward to any news!

I was able to make one coating of the thiocyanate sensitized BrI the other night. Maybe this afternoon I can make some first test exposures.

 

[Photo Engineer]

Well, something came up at the last minute and Nick and I had to cancel. So, the work extensions have to wait a week. But we are in a solid position without much pushing and I think we will soon be at a very good ISO 80 or higher with an ortho, non ammonia emulsion.

PE

 

[wildbillbugman]

kb3lms,
As far as red sensitization is concerned, I have been using Denise's pinocyanol. Their is also eriochrome cyanine. That works too. In both cases, erythrosine is used as a green absorption dye. Artcraft has been very cooperative in getting dyes for me.
I am working on something very weird related to pan emulsions. But I will not open my mouth until I am sure of it. Maybe next week.
Bill

 

[kb3lms]

eriochrome cyanine

Really? That is not so expensive. I have used stains-all and it works, too.

 

[Photo Engineer]

Where do you guys get these dyes? I have gotten mine from Sands and Honeywell.

PE

 

[dwross]

A while back I gave Photographers' Formulary some erythrosin powder to mix up into photosensitizing solution to sell. I don't know if they have done that yet. They may be waiting for a demand. If anyone were interested, they might contact PF and ask. As far as my experience goes, it works perfectly to create an ortho emulsion and as Bill said, it is one half of pan sensitizing. (More info here for anyone interested: http://www.thelightfarm.com/cgi-bin/htmltutgen.py?content=01Sep2013 )