Film Developing Chemicals
Developing film is nothing more than a series of chemicals. The only thing that varies is how long you leave the chemicals in the tank. Primarily these are some chemicals required to develop films: Developer, Stop Bath, Fixer and Photo-flo(optional). While the image has been captured on the film, it is not visible until the developer brings out the silver halides in the film. While the developer will bring out the image captured on the film, it will continue to develop the picture until it is stopped. This will ruin the film, and is what is referred to as overexposure. The photographic fixer is the final process in developing the film. The fixer "fixes" the image in place by removing the unexposed silver halides in the film.
Film Developing Tanks / Reels
People use developing tanks with special film reels to develop film rolls or sheets. After loading your film on the reel, you place it in a film developing tank with the chemistry mixture to develop. Most tanks have instructions for the proper amount of developing chemicals for specific film formats. The reel locks onto a center post, and chemicals mix consistently during the process to ensure the film gets a thorough coat. Using film developing tanks with darkroom print washers and dryers helps you develop your film from start to finish.