Category Archives: Alternative processes

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.



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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.

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.

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Heavily caffeinated.

To anyone who knows my ongoing love affair with 1,3,7-trimethylxanthene, you may as well skip over this entry. Those cunning Costa-Ricans (specifically Saul BolaƱos) have discovered a silver negative process that utilises coffee in the development process.

The obvious hook is that you have to use their proprietary “photo transfer paper”, which sounds an awful lot like a commercial process dressed in ratty hipster jeans. At least they are kind enough to inform us that it is a “silver-based” process and tell us that the magical compound in the coffee is “CAFFEIC ACID, ( 3,4-Dihydrocinnamic Acid )”.

Also on this page, is a section on making your own silver (chloride) – gelatine emulsion (again using proprietary components), and a method for coating 35-mm glass plates for use in consumer film cameras.

I Just Wish The Web Developer Would Stop Capitalising Every Damn Thing!

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Filed under Alternative processes, Chemistry