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emulsion recipe ala EK and A. Gassan text
Here's a reference for making your own photo emulsion: Kodak pamphlet AJ-12 "Making a Photographic Emulsion".
Arnold Gassan also gives an outline of that pamphlet in his Handbook for Contemporary Photography 4th ed., pg.177.
The sequence of mixing the chemicals is not entirely clear but, basically, Gassan's recipe is:
(NOTE: NO IRON SHOULD CONTACT THE EMULSION AT ANY POINT)
45gm Silver Nitrate is dissolved in 415ml distilled water to form a solution. A second solution consists of 10 gm gelatin dissolved in 385ml distilled water and allowed to swell. 30gm potassium bromide and 1.3 gm potassium iodide are (apparently) added to the gelatin solution.
The gelatin solution is raised to 44C and the silver nitrate solution is added slowly (20ml every 10 seconds) with constant stirring. The liter of resultant emulsion is allowed to cool and gel. The gel is then "noodled" through several layers of cheesecloth (by twisting) and collected in a pan where it is washed in cool water, allowed to sit for a few minutes, drained and the noodling is then repeated for a total of 5 cycles to mechanically disperse the silver and remove excess salts. To use , warm the emulsion slowly to 40C and coat the paper or surface. Gassan states the emulsion ASA is about 10 and orthochromatic.
The emulsion should be concocted under safelight conditions and all the noodling done under safelight conditions as well. You'll also need an opaque bottle to store the stuff and latex gloves and eye goggles are needed when straining, etc. for safety reasons and because it can been messy noodling this stuff under safelights.
Joe