My first attempt... is in the fridge.
I'm working at the local university to make an emulsion... And my brain hurts already. And it's not the strange chemical I knocked over in the fridge!
...All that said, I'm using the emulsion number two from Silver Gelatin: A User's Guide to Photographic Emulsions. The fomula, eh, I'll type it up. Why not.
Water at 40C 140mL
Inert gelatin 7.5g
Water at 40C 120mL
Water at 50C 110mL
Inert gelatin 16g
KBr (.8% sol) 10mL
The process is in a nutshell (for those of you interested), B->A over 30 secs. Hold the solution then at 45C for about ten minutes. Immerse into 2C water (cold water and ice) to gel the solution and stop the ripening.
This is the stopping point for me today. I have the emulsion in the fridge and will add solution C tomorrow in the following manner:
Shred and wash the B and A solution in water fro two hours, then in purified water for 20 minutes (I'll probably be using distilled; I used DI water for the chemicals). Melt the emulsion and ass Solution C. Raise the temperature to 50C
The book also has the following: adding 7mL of a 1% KBr solution to minimize fog for the next 45-90 minute digestion at 50C. More time=more speed and contrast (and fog).
Finally, 1g of KBr per 20g AgNO3 for stabilizing and optionally phenol at 1% for bactericide.
I didn't have a bucket with ice to cool the gel in after mixing, so I stuck it in the freezer. My temperature control was a bit screwy (but I did get close with a refreshingly fast mercury thermo).
I could probably do this easier in my home darkroom in all honesty... Light proofing a fume hood isn't the easiest thing in the world. I spent several hours trying that. I was miserable.
Anyway, enjoy the formula, and PE, any hints would be most appreciated. I plan on having a coating and print and develop a print here within a week. I'll keep you all posted.
Last edited by Jadedoto; 08-15-2007 at 09:11 PM. Click to view previous post history.
It's nice to see someone else experimenting!
I'm all agog to hear how it goes - good luck!
Lens caps and cable releases can become invisible at will. :D
Don't freeze any emulsion. You can ruin it.
Thymol is better than phenol, but you have to dissolve it in iso propyl or methyl alcohol. One drop of a 10% solution / 100 grams of emulsion is enough. Without either phenol or thymol, the emulsion will begin to spoil in a few weeks, otherwise it could keep for months in the fridge.
Try to use distilled water throughout the wash, as the impurities in tap water can fog the emulsion. I keep a gallon of DW in my fridge just for washing.
That is a lot of KBr to be adding at the end, but may be needed for stabilzation. IDK for sure. Mine require no such addition. I have not tried this emulsion. It will have most of the iodide trapped in the center of the crystal and have a low ISO value of probably about 3 in a camera. It will be about 3 - 5 stops slower than an enlarging paper.
I'm not sure about contrast. Many formulas like this have good contrast but some have low contrast.
Vince, with some experience it's possible to get good speed and contrast with an emulsion like this. However it needs a lot of experimentation and testing varying the ripening and after-ripening times, also as Ron has posted elsewhere doping the gelatin helps to get greater sensitivity as well.
It's definitely possible to make an enlarging speed emulsion this way, I did for about 10 years, and it was very close in speed / contrast to the Ilfospeed Grade 3 emulsion which I had to test from Ilford.
While I can't find my notebooks, (they are packed away in storage as I'm moving continents) but I have found some of the Agfa emulsion formulae published by the allies after WWII.
Lets hope your formulas never get lost in the dustbin of history. I hope your move goes well.
Sponsored Ad. (Subscribers to APUG have the option to remove this ad.)
Actually I began my emulsion/coating planning while in hospital for 12 weeks on traction with a broken leg. First I went down a commercial route, I remember I was the first UK customer of Rockland Colloids. But it wasn't good enough for what I wanted so my first experiments with emulsion making was from a little Kodak sheet on emulsion making and my first attempt gave reasonably good results.
Doing a lot of research and reading, particularly "Photographic Emulsion" by B H, etc. Carroll, (Focal Press), looking at the published Agfa formulae, also quite a few Russian formulae, meant I was quickly able to evolve an appropriate emulsion that I could apply by spraying. I guess it could be coated in other ways as well, I just never tried.
For anyone wanting to make their own emulsions I have to highly recommend the Hubbard, Caroll etc book, Photographic Emulsions, not for the formulae they used but rather the experiments they did because they provide an invaluable guide to how an emulsion changes as you vary a variety of parameters.
Can you provide citations for these, by chance?
Originally Posted by Ian Grant
Yes they were printed in Glafkiddes, PE might correct the spelling, after the war, Kodak had a set, the books were extremely limited in distribution.
I borrowed a copy from a member of the Lumiere family, (Autochrome process) actually he was English his mother was from the Lumiere family, and Tim was a technical advisor to Elinchrom and Alpha.
Getting hold of the books is difficult, so when I did I copied every thing of relevance to me. I found the negatives a couple of hours ago, so can access them easily, when I've got time and in the right continent.
Originally Posted by Neanderman
I remember Burt Carroll very well. He and his wife were close friends of ours up until his death. We used to vacation at the Glen Iris Inn at Letchworth park and Burt and I used to sit on the porch after dinner and talk about photography. That really brings back some old times.
At that time, he was professor emeritus of photography at RIT and a fellow of the research staff at EK and member of the senior staff (retired).
I think that Glafkides is the correct spelling, but not sure. I've met him once unless it was another person with the same name at EK. I never talked to him at length.
There are some of the things you mention above, in abbreviated form, in the text "Photographic Theory" by James and Higgins. It is a mere chapter but very interesting.
There was also a set of monographs issued publicly by the Kodak Research Labs over a period of about 10 years. They used to give them out to empolyees and were also sold. Some of them contain very valuable information if you put them together with some of the published texts and patents.
Ron, I have the luxury of distilled water on tap there. The problem is, however, the place wasn't build with blackout in mind. You should see my ... "lightproofing" I set up around the hood- some 50 feet of 3mil plastic in various layers and forms. It still leaks light, so until I get a definite way of closing all light out there, I don't think I'll be doing any serious attempts that require control outside of my homemade lightproof bag.
Originally Posted by Photo Engineer
I wish I could take the chemicals home to my darkroom... I'd have to drag water but that's easier than light proofing this place!
Ian, I've been reading this forum here extensively as well as studying the bok I do have like the uber-Bible. I hope it goes well. The first choice emulsion (which I don't have and at the moment can't get the chemicals for) is faster and higher contrast- an SRAD as Ron would say. I'll try that if this formula is way off base (which I have a gut feeling it won't be).
More to come!