Photographic formulas from The Frugal Photographer

Here, we have a collection of formulae from the Frugal Photographer website. At least one seems to have been lifted from The Darkroom Cookbook, Third Edition (Anchell, 2008), which is as in-depth a resource as any modern photographer could want.

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Bonus Emulsion Formulae from “The Book of Photography”

“The Book of Photography” (Hasluck, 1907) chapter on “Plates and Films” includes two formulations for a silver (bromide) – gelatine emulsion. Starting with the simplest [formatting and numbering is mine]: ”

1. gelatine, 30 grains, [dissolved in] water, 1 [fluid] ounce ;
2. silver nitrate, 175 grs., water, 1/2 oz. ;
3. potassium bromide, 140 grs., water, 1 oz. ;
4. gelatine, 240 grs., water 2 oz.

… each of the ingredients [1, 2, 3, 4] dissolved separately[, and then combined ((1+2)+( 3+4))].” There’s also more sensitive (“more rapid”) emulsion given: ”

1. Nelson’s gelatine No. 1 soluble, 30 grs., water, 1 oz. ;
2. silver nitrate, 175 grs., water, 1/2 oz. ;
3. potassium bromide, 130 grs., water, 1 oz. ;
4. potassium iodide, 5 grs., water 1 oz. ;
5. hard gelatine, 240 grs., water 2 oz.”

– which, I’d have thought, ought to give a slower emulsion, as AgI is nominally less photosensitive than AgBr. I presume the additional sensitivity has something to do with differing crystal habit.

Update: I’ve cracked it. Mixed AgI + AgBr grains are more sensitive because the iodide:

1. introduces additional irregularities into the cubic AgBr crystal lattice,
2. interacts with longer wavelengths of light than AgBr, extending its spectral range,
3. accelerates crystal growth, and thus accelerates “ripening” of the emulsion.

(Source)(Another)

Round-up: DIY Silver Gelatine Emulsions

I’m afraid this post is nothing but a list of links to various, from-scratch, silver-gelatine, emulsion recipes from around the web.

• Kitchen Lab Emulsions
• Gelatin History
• Silver Gelatin Emulsions
• Film Emulsion
• The silver gelatin dry plate process
• Homemade Photo Emulsion

There appears to be some variations of formulation in these recipes, suggesting there is latitude for error and experimentation. I’ve recently become interested in DIY photochemistry, and will have occasion to use a large-format camera for course work, so yeah, the gears are turning.

The bigger challenge would seem to be the acquisition of chemicals.