Photographic printing is the process of producing a final image on paper for viewing, using chemically sensitized paper. The paper is exposed to a photographic negative, a positive transparency (or slide), or a digital image file projected using an enlarger or digital exposure unit such as a LightJet or Minilab printer. Alternatively, the negative or transparency may be placed atop the paper and directly exposed, creating a contact print. Digital photographs are commonly printed on plain paper, for example by a color printer, but this is not considered "photographic printing".
Following exposure, the paper is processed to reveal and make permanent the latent image.
The process consists of four major steps, performed in a photographic darkroom or within an automated photo printing machine. These steps are:
Optionally, after fixing, the print is treated with a hypo clearing agent to ensure complete removal of the fixer, which would otherwise compromise the long term stability of the image. Prints can be chemically toned or hand coloured after processing.
Kodak Panalure is a panchromatic black-and-white photographic printing paper. Panalure was developed to facilitate the printing of full-tone black-and-white images from colour negatives – a difficult task with conventional orthochromatic papers due to the orange tint of the film base. Panalure also finds application as paper negatives in large format cameras. It is generally not suitable for conventional black-and-white printing, since it must be handled and developed in near-complete darkness.
Kodak has announced that it will no longer produce or sell this product.[when?] However, as of early 2006, it is still available from various online retailers.
Silver mirroring, or "silvering", is a degradation process of old black-and white-photographic prints caused by conversion of the black silver oxide to silver metal. This results in a slightly bluish, reflective patch in the darkest part of a print or negative when examined in raking light. It often indicates improper storage of the prints.
For more info see also: Chromogenic print
Colour papers require specific chemical processing in proprietary chemicals. Today's processes are called RA-4, which is for printing colour negatives, and Ilfochrome, for colour transparencies.