Turn off the darkroom lights and put a blank piece of photographic paper on the darkroom counter and partially cover it with a book or something. Then turn on the safe light and leave for 5 minutes - develop the paper and see if you can see a change from the white of the paper to a grey shade where the paper was exposed to the safe light. If there is a difference in shade then your safe light is not adequate. Back to Top 11. I was just wondering how the photographs actually are produced with the chemicals involved.
Photographic paper is coated with invisible silver halide crystals.
Silver halides change from white to black metallic silver when exposed to light. The developer reacts with the exposed crystals of silver halide, freeing the silver from its compound and depositing it as tiny, irregular grains of metallic silver. After developing to the desired effect, the development must be stopped so that print will not darken further. This is done by placing the print into an acid stop bath for about 10 seconds. The print then must be washed to remove any residual chemicals and dissolved silver salts.