Newbie Formula for Silver Emulsion

[Malco_123]

http://unblinkingeye.com/Articles/Emulsion/emulsion.html

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.

Malco

 

[nickandre]

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.

 

[Malco_123]

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?

 

[Photo Engineer]

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.

PE

 

[nickandre]

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?

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.)

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.

 

[Photo Engineer]

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.

PE

 

[dwross]

Hi All,

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.

http://www.thelightfarm.com/Map/DryPlate/Recipes2/DryPlateSection.htm

Good luck and fun,
Denise

 

[Malco_123]

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.

http://www.thelightfarm.com/Map/DryPlate/Recipes2/DryPlateSection.htm

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,

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.

Also,
Thanks to everyone who responded. I didn't expect to get so many awnsers so quickly. This really is a great community.

 

[Photo Engineer]

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.)

PE

 

[Malco_123]

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.)

PE

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?
And silver nitrate is around 159.86 g/mol, so you were right.

 

[Ian Grant]

A 0.1% solution means 1 gram of Sodium Thiosulphate dissolved in Water made up to 1 litre.

Ian

 

[Photo Engineer]

This is 0.1 gram of Sodium Thiosulfate Pentahydrate in 99.9 grams of Distilled Water. So the actual amount of solution used is very very tiny to use 100 mg (or 0.1 grams) of Hypo / 160 grams of Silver Nitrate.

If you used 16 grams of Silver Nitrate, then you would use 10 ml of this solution (10 grams actually). If you used 8 grams of Silver Nitrate, then you would use 5 ml of this solution.

After your emulsion is made and washed, you add this solution and heat to 60 deg C for about 1 hour. the time will vary. Without this treatment, the emulsion will be slow and low in contrast but with this treatment it can gain up to 3 - 5 stops in speed and 1 - 3 grades in contrast. You have to be careful though as you can fog the emulsion. I run a test before and after the hypo treatment to show the difference in result. To do this, I remove 10% of a 100 gram emulsion (10 grams) and coat it before treatment. I reduce the hypo addition by 10% to compensate and then retest to show the change in speed and contrast.

This process is called Sulfur Sensitization or Finishing. It can be made stronger by using Sulfur + Gold. but that is another story.

PE

 

[Malco_123]

This is 0.1 gram of Sodium Thiosulfate Pentahydrate in 99.9 grams of Distilled Water. So the actual amount of solution used is very very tiny to use 100 mg (or 0.1 grams) of Hypo / 160 grams of Silver Nitrate.

If you used 16 grams of Silver Nitrate, then you would use 10 ml of this solution (10 grams actually). If you used 8 grams of Silver Nitrate, then you would use 5 ml of this solution.

After your emulsion is made and washed, you add this solution and heat to 60 deg C for about 1 hour. the time will vary. Without this treatment, the emulsion will be slow and low in contrast but with this treatment it can gain up to 3 - 5 stops in speed and 1 - 3 grades in contrast. You have to be careful though as you can fog the emulsion. I run a test before and after the hypo treatment to show the difference in result. To do this, I remove 10% of a 100 gram emulsion (10 grams) and coat it before treatment. I reduce the hypo addition by 10% to compensate and then retest to show the change in speed and contrast.

This process is called Sulfur Sensitization or Finishing. It can be made stronger by using Sulfur + Gold. but that is another story.

PE

How critical is this process to produceing good plates? This is my first attempt at making an emulsion so this is all new to me. The rough Idea I have in my head is that I want to try and reproduce some period photos. The quality is important but not critical, mostly I just need to be able to get my hands on some of the materials. the overall ISO is important as I'm going to be using a pinhole camera and my fstop is going to be huge. All my shots will be outside in the sun so it shouldn't be that bad, plus it will be easier for me to do 30 second to 5 minute exposures than 1/2 second to 5 second exposures.

What I'm trying to say is that I'm new to this and don't have a lot of disposable income, so I'm looking for a formula and process that is forgiving so I don't blow my entire budget by making a small mistake.

but as I have learned analog photography is not very forgiving, so this request may be outragously naïve.

 

[dwross]

Hi Malco,

I think you'll be very satisfied with the results you get from Kevin's recipe. The best thing you can do at this stage of your learning curve is just plain make an emulsion. There's no substitute for a little hands-on experience. If you're interested in 'period' photography you don't even have to worry about spectrum sensitizing (just pick a period far enough back)

I'm guessing that by huge fstop you mean a big number, so a small aperture. Pour a number of plates and use them sequentially to test your exposure. If you are consistent with your emulsion making process and testing, you should be able to get very close on the exposure time from your second and subsequent batches. By batch three, you'll be an old hand.

You can order all the materials from the Photographers' Formulary in Montana. They have small quantities of everything you'll need, except for glass.
http://www.photoformulary.com/DesktopDefault.aspx

d

 

[Photo Engineer]

If you do use glass, you will need glass plate holders or something like it for your camera. Otherwise you can use the Melenex support sold by the Formulary and use it just as you would use sheet film.

PE

 

[dwross]

Melenex is a great product, but it gives a bit different look than glass. Also, especially if you are planning on pouring rather than spreading the emulsion, film is tricky to hold for a good pour (unless each piece is backed by a matching, or slightly smaller, piece of glass - something of a redundancy). Fortunately, it is very easy to make plate holders from old, wooden film holders. It pretty intuitive, but here's a short tutorial:
http://www.thelightfarm.com/Map/DryPlate/PlateHolders/DryPlateSection.htm

d

 

[Photo Engineer]

Just an FYI, but you can tape a 4x5 sheet of Melenex to a larger sheet of glass or plastic and then pour the emulsion down the tilted "plate" letting the excess run off into a catch basin for re-use.

This is the film version of coating plates. A little messy and hard but if you practice with plain gelatin with food dye in it, that should help you learn the basics in the light and with little cost. Just remember that only one side of the Melenex is coatable and the Formulary notches it properly to conform to normal practice with the notch in the upper right corner with the good side facing you.

You will need to maintain the gelatin percentage and temperature to get a good flow using this method.

PE

 

[Ray Rogers]

And silver nitrate is around 159.86 g/mol, so you were right.

???

On this side of the world it is more like 169.87

 

[Malco_123]

On this side of the world it is more like 169.87

Oh, sorry must have messed up when adding the atomic weights.

Also I'm picking up some 4x5 holders from a friend, but I don't think I will bother with them for the glass plates. I'm just going to slide em into a old pinhole camera I made and secure them in there. Plus I think film will be too flimsy and messy for me to start with so im going to go glass.

Oh and a quick question. Is there any metals that the emulsion is particularly reactive to? I was thinking of spreading the emulsions onto a metal plate, probably copper, aluminum, or zinc, and then making the positive onto that. But I don't know if it will work because the emulsion might automatically oxidize (reduce?) when it is applied to the metal. does anyone have any experince of using metal as opposed to glass or film?

 

[Photo Engineer]

Do not use copper, Aluminum, Zinc or Iron. The only metals that emulsions tolerate well are Stainless Steel and Titanium. They will corrode most others and in doing so will fog or spoil in some way.

And, I missed the molecular weight as I have a small crib sheet due to my old age. Ray can attest to how old we are both getting. I'm sure he looked it up.

PE

 

[Malco_123]

Ok thanks, The stainless steel should look nice, or maybe a copper that has been coated with some sort of plastic....
owell steel should do fine.

 

[Ray Rogers]

I missed the molecular weight as I have a small crib sheet due to my old age. Ray can attest to how old we are both getting.
I'm sure he looked it up.

PE

Ouch!
Right and wrong at the same time!

Actually,
AgNO3 and KBr are the ony two I have committed to memory!

I did confirm before posting though as I was afraid the scientists that rule the world might have changed their minds without consulting me first.

What's a crib sheet?

 

[Photo Engineer]

A cheat sheet! No need for the "ouch" as there was a similey in there for you Ray.

PE

 

[Ray Rogers]

Do not use copper, Aluminum, Zinc or Iron. The only metals that emulsions tolerate well are Stainless Steel and Titanium. They will corrode most others and in doing so will fog or spoil in some way.PE

Have you heard of having trouble (after much use) with even with Kodak's kettles ?
I even mean cosmetic defects - forgetting fog etc. for the time being...
I ask because I've seen presumably very good quality research kettles in different labs (RIT for instance) get pock marks during normal use.

Ray

 

[Ray Rogers]

there was a similey in there for you Ray.
PE

Thank You.
Simileys are good.
The World Needs More Simileys!