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.

Printing on black-and-white paper

The process consists of four major steps, performed in a photographic darkroom or within an automated photo printing machine. These steps are: *Exposure of the image onto the sensitized paper using a contact printer or enlarger; * Processing of the latent image using the following chemical process: **Development of the exposed image reduces the silver halide in the latent image to metallic silver; **Stopping development by neutralising, diluting or removing the developing chemicals; **Fixing the image by dissolving undeveloped silver halide from the light-sensitive emulsion: **Washing thoroughly to remove processing chemicals protects the finished print from fading and deterioration. 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.

Panalure paper

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. However, , it is still available from various online retailers.

Silver mirroring

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.Notch Code (2012):
Forms of Photograph Degradation: Silver Mirroring
'. Archives and Special Collections Blog University Libraries, University of South Dakota; dated January 17, 2012. Accessed on 2020-05-05.

Printing on coloured paper

''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.

Printing from colour negatives

*Colour negatives are printed on RA-4 papers and produce a Type C print. These are essentially the same as colour negative films in that they consist of three emulsion layers, each sensitive to red,

green Green is the color between cyan and yellow on the visible spectrum. It is evoked by light which has a dominant wavelength of roughly 495570 nm. In subtractive color systems, used in painting and color printing, it is created by a com ...

and

blue Blue is one of the three primary colours in the RYB color model, RYB colour model (traditional colour theory), as well as in the RGB color model, RGB (additive) colour model. It lies between Violet (color), violet and cyan on the optical spe ...

light. Upon processing, colour couplers produce

cyan Cyan () is the color between blue and green on the visible spectrum of light. It is evoked by light with a predominant wavelength between 500 and 520 nm, between the wavelengths of green and blue. In the subtractive color system, or CMYK c ...

magenta Magenta () is a purple-red color. On color wheels of the RGB color model, RGB (additive) and subtractive color, CMY (subtractive) color models, it is located precisely midway between blue and red. It is one of the four colors of ink used in colo ...

and

yellow Yellow is the color between green and orange on the spectrum of light. It is evoked by light with a dominant wavelength of roughly 575585 nm. It is a primary color in subtractive color systems, used in painting or color printing. In t ...

dyes, representing the true colours of the subject. The processing sequence is very similar to the C-41 process. *Rollei makes a film called 'Digibase 200 Pro' that is like a conventional C-41 film but it has no orange mask, allowing easy prints on black-and-white paper with a grade 2 or 3 variable contrast filter

Printing from colour transparencies

*Ilfochrome paper uses the dye destruction process to produce prints from positive transparencies. The colour dyes are incorporated into the paper and bleached during processing. Ilfochrome, EP2 and Type R print papers and chemicals are no longer in production.

References

External links

Evolution of photo printing technologies: from chemical processes to digital innovations, from Daguerreotypes to Nanoprinting
{{photography subject Photographic processes Non-impact printing Printing technology