Newbie Formula for Silver Emulsion
I found this formula and procedure on line and was wondering if any with more experience could awnser a couple of questions:
1. Does this formula seem like it would work?
2. Do all emulsions need a sensitizeing dye?
3. What would you use to Stop and Fix these plates, if anything?
and finally more of a basic question:
4. How do you determine an emulsion's ISO, and will it be fairly constant throughout all the plates that use that particular batch?
I am a really new to making my own film and stuff, but I do know my way around a darkroom. Any help, perhaps a better beginners formula, would be apreciated.
I have limited knowledge but I'll give a few of these a go. It's published on unblinkingeye which seems to indicate it would work, after all these have been around for two centuries. Halide on its own is only sensitive to blue light. Sensitizing dyes are required to make films which are sensitive to other colors besides blue. You would develop this like any other film, as that's what it is. This is sort of like getting "liquid light emulsion" or whatever it is that you can coat t-shirts with or whatever.
The stated settings are F8 1/30 which equates to ISO 8 using the sunny 16 rule. The speed is varied based on the rate of addition of the nitrate solution and the ripening process. This is all stated on the page you provided.
Sorry I wasn't more specific.
There are many diffrent types of stop and fix, so I was wondering what type I would use.
Also what exactly is a sensetizing dye, I know what it does, but what chemical is it? Also when and how would I add it to the plate?
Step #10 is incorrrect. You noodle via a potato ricer and then wash while in a cheese cloth. You must harden with Glyoxal if on film support or with chrome alum if on glass.
This should be about an ISO 3 - 6 emulsion. It will be Blue/UV sensitive only. Further steps are needed to increase speed or sensitiivity. This forum has examples of noodle washing and sensitizing dyes.
Stop as in Acetic Acid or vinegar or even water and fix as in sodium thiosulfate (hypo). There are only two. I don't know if this requires a hardener but if any film did it would be this one. Add some if you end up needing it (like emulsion falling off your plates/film base.)
Originally Posted by Malco_123
This may be entirely wrong but a sensitizing dye is a particle/chemical/dye of some sort which absorbs light of wavelengths other than blue/UV, converting and transfering said energy to the halide, exposing it. I do know that the end effect is sensitivity to wavelengths of light other than blue.
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Almost any home coated emulsion will need a hardening fix or a pre-hardener along with hardening in the coating just to prevent defects. We do not have access to the very strong hardeners used by the major manufacturers, nor would we want to use them. They are extremely toxic, react rapidly and are non-toxic after reacting.
I don't use a hardener in my dry plate emulsions and I have almost zip defects. I use a hardening fixer (Zone VI from Calumet). That seems enough to do the trick.
The simplest recipe I know has been contributed to The Light Farm by Kevin Klein. He was generous enough to send me a plate and a number of prints from his plates. They look very good.
Good luck and fun,
This looks much better to suit my needs, as I am a stundent and silver nitrate is really expensive. Though this formula brings up more questions,
Originally Posted by dwross
1. Can I substitute commercial grade gelatin? ( I really don't know where to find photo grade gelatin, as I don't really live close to any big cities that have analog photo shops)
2. I'm guessing that this formula is only blue/UV sensitive too, since it dosen't mention sensitizing dyes.
3. I'm also assuming that the "Hypo Solution" is sodium thiosulfate.
Thanks to everyone who responded. I didn't expect to get so many awnsers so quickly. This really is a great community.
Commercial food grade gelatin can be used if you really really must, but the results will vary more and may dissapoint you due to the additives. I've used it, and have not been happy with the results.
Photo Grade gelatin is sold by the photographers formulary in Montana. They sell Eastman Gelatin from Kodak in the proper grade for these emulsions.
The emulsions are only blue sensitive, but in this forum are listed methods for making green (ortho) sensitive emulsions. Examples are posted. The food dye Erythrosine can be used for this and it is quite inexpensive compared to the other dyes.
For sensitizing, I use a 0.1% solution of Sodium Thiosulfate pentahydrate in water at a ratio of about 100 mg of hypo per every mole or ~160 g of Silver Nitrate used. (I rounded the sillver nitrate as I don't remember the exact molecular weight right now.)
I don't quite understand what you mean by 0.1% solution. Just coming out of Grade 12 Uninversity chemistry, could you please give me an aproximate mole per liter concentration?
Originally Posted by Photo Engineer
And silver nitrate is around 159.86 g/mol, so you were right.