How is a photograph developed?

Answer

Film is developed in a light tight bag or room and developed with three chemicals and water: developer, water, fix, hypo, and wash, with times dependent on the type of film. When your negatives are dry you can take a section of them and slide them into the film carrier and place it in the enlarger. I prefer to turn on the light all the way to the furthest brightness and then use the handles or switches on the side to adjust the focus. There is also a wheel on the side of the enlarger to adjust the size. After determining the focus, turn down the light two stops and take a small piece of photo paper and test the times with intervals of 3 seconds. Take the piece of paper and leave it in the developer with agitation for one minute and decide which exposure time looks best. Proceed with a larger sheet of paper and finish the developing with water, fix, and a water bath, air dry or blow dry to finish. And you have a photo!
howstuffworks.com also has an article about instant cameras and how instant photos like Polaroid photos are developed.

 

Further to the above which only covers monochrome colour photography can involve the use of seven different chemicals. Everything has to be processed in complete darkness. The film is processed as per the mono system except you work at higher temperatures using colour chemistry. You can use the same processing tank as in black and white. However you need to keep the tank in hot water at the temperature required. Printing has to be done in complete darkness which is why most of us either have an expensive processor or leave it to a colour lab. You can use a dish system but it is not very consistent. To be honest mono can be fun but colour can be a nightmare so I suggest you take your colour to a lab.

 

Developing Color

There are four types of color processes: color print film, color slide film, prints from negatives and prints from slides. The critical thing in developing color is temperature--it runs at 38 degrees C, plus or minus 1/4 degree C. That is a REAL tight standard, but it's attainable. Some people use styrofoam coolers and aquarium heaters, others fill the bathtub with 102-degree water and the real rich people used to buy special desktop color processing machines. These were made in Germany by a company called Jobo and they've been discontinued since 2006, but you can occasionally find used ones.

Color print is REAL easy--3 minutes 15 seconds in developer, wash the film, 6 minutes 30 seconds in bleach (which converts metallic silver into fixer-soluble silver halide--color images are made from dyes, there's no silver in the final image), wash the film, 6 minutes 30 seconds in fixer, wash for 10 minutes, soak in stabilizer for a minute, squeegee and dry. In the modern era the best way to print this stuff is to take it to Walmart and run it through their self-service printing kiosk.

Color slides require either three or seven baths, and the three-bath systems are awful. The three-bath system is first developer, color developer and bleach/fix. All film produces negatives no matter what kind it is. If you want a positive image, you develop the negative in a bath that won't create any dye (it's a black and white developer; I once tried developing black and white film in this and it turns out to work pretty well, but if you're looking for lots of contrast this is the stuff to use.) then chemically fog the remaining silver, develop it in a dye-generating developer, then bleach, fix and stabilizer. The seven-bath system, which is sometimes called a "six-bath" system, is first developer, reversal bath, color developer, prebleach (used to be called "conditioner"), bleach, fix and stabilizer. The three-bath process puts the reversal agent in the color developer, combines bleach and fix (which MOST companies do these days--Kodak's official process was designed decades ago when the bleach wasn't the same product it is now) and eliminates the prebleach. Putting the reversal agent in the color developer makes the life of the CD real short, so if you get one of these kits use it and dump it the same day.

As for printing, if you're not making 20x24s or something you're far better off to go to a PhotoMaker kiosk and do it there.  

Photo Development

Go to HowStuffWorks.com and search for 'film' or 'photography'. One of the first few results that turns up will be an article called "How Photographic Film Works."
This article discusses developing both color and black & white film.