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Photo 118- Advanced Techniques  

Making Photographic Emulsions

 

This emulsion is similar to Rocklands paint on Liquid Light. You have a bit more control over the speed and quailty as well as the contrast that you can achieve. Where gloves to avoid getting chemistry on your self or clothing. Be patient to obtain the best results. If you have questions please contact me and I will try to answer them. I can be reached via ICQ#19623319. Download ICQ if you don't have it.

 Now you may adapt what ever necessary to make this emulsion. You can use kitchen apparatus to melt and do what ever is needed. Clean containers etc. is essential to positive outcomes with this project. You can vary some items as far as the amounts and such. Pre-coating your paper (if you are using paper) will help in the reflection quality of the print. Dyes can be added to the emulsion to tint the colouration of the final image upon development. Remember this is just the starting point of emulsion making. Make it fun

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Preparation of a Photographic Emulsion

Procedure

With the lights on, dissolve 1.2 g of potassium chloride and 0.60 g of potassium bromide in 50.0 ml of distilled water. Place this solution on a stirrer hot plate and bring the temperature to 35C. Add 10.0 g gelatin. Set this aside to thicken. In another beaker dissolve 3.0 g of silver nitrate in 30.0 ml of distilled water. Assemble the constant temperature apparatus shown below. Run the hot water for a while to ensure temperature is about 50C. Heat the potassium chloride-gelatin mixture in the beaker to about 50C.

The remainder of this experiment must be done with a safety light as the photographic emulsion is extremely light sensitive once it is prepared. Add the silver nitrate solution slowly, with continued stirring, to the gelatin-halide mixture. The rate of addition should be no greater than 1 mL per 3 seconds. Maintain the temperature at 45C, with stirring for 2 hours. At the end of this digestion period, add another 5.0 g of gelatin. Once this has dissolved, you can chill the emulsion with an ice bath. If necessary, the experiment can be stopped at this point. Wrap the emulsion beaker with foil, label and store in the refrigerator.

If the emulsion is shredded and washed, then cold tones will be observed. If it is left unwashed, warm tones will be obtained. The emulsion should now be melted and with continuous stirring, held at approximately 45C for 1 hours. At the end of this second digestion period. 0.125 g of chrome alum
(KCr(SO4)212H2O), (dissolved in a minimum of H2O) can then be added.

The emulsion can now be coated onto any desired object. This should be done as quickly as possible because the emulsion can get very thick when the chrome alum is added. Paint the emulison on to your substrat. A thickness of less than 1 mm is desired. Try to make all the coatings about the same thickness. The substrat can now be allowed to cool, wrapped in foil and stored in the refrigerator until needed.

Expose by setting the negative directly on the emulsion or use an enlarger. Start with the same exposures that are used for photographic papers. Develop the emulsion by emersion in the developer, stop bath and fixer. Use the same times you used for photographic papers. Experiment with your emulsion to obtain the best possible print.