RA-4 is

Kodak The Eastman Kodak Company, referred to simply as Kodak (), is an American public company that produces various products related to its historic basis in film photography. The company is headquartered in Rochester, New York, and is incorporated i ...

's proprietary name for the chemical process most commonly used to make color photographic prints. It is used for both

minilab A minilab is a small photographic Film developing, developing and printing system or machine, as opposed to large centralized photo developing labs. Many retail stores use film or digital minilabs to provide on-site photo finishing services. With ...

wet silver halide digital printers of the types most common today in photo labs and drug stores, and for prints made with older-type optical enlargers and manual processing. More specifically, common color

photographic paper Photographic paper is a coated paper, paper coated with a light-sensitive chemical, used for making photographic prints. When photographic paper is exposed to light, it captures a latent image that is then Photographic developer, developed to form ...

is carefully exposed to form a

latent image A latent image is an invisible image produced by the exposure to light of a photosensitive material such as photographic film. When photographic film is developed, the area that was exposed darkens and forms a visible image. In the early days of ...

of the picture, and then the paper is run through the series of chemicals that together comprise the RA-4 process to convert the latent image into the final print. RA-4 uses

Color Developing Agent 3 The third in the series of color developing agents used in developing color films, commonly known as CD-3, is chemically known as N- 4-Amino-3-methylphenyl)ethylamino.html" ;"title="-[(4-Amino-3-methylphenyl)ethylamino">-[(4-Amino-3-methylphenyl)e ...

, in combination with color couplers in the emulsion to generate color dyes. RA-4 is a standardized chromogenic process used worldwide to make prints with a variety of equipment, photographic paper, and chemicals. Kodak created the RA-4 process for its color negative photographic papers. Fujifilm, Fuji, [

Agfa Agfa-Gevaert N.V. (Agfa) is a Belgian-German multinational corporation that develops, manufactures, and distributes Analog photography, analogue and digital imaging products, software, and systems. The company began as a dye manufacturer in 1867 ...

, and other present and past photographic supply companies also make or have made both papers that are compatible with the Kodak chemicals, and chemicals that are compatible with the Kodak papers. These other companies typically call their equivalent processes by other names, but to most photographers, RA-4 is used as a generic term. The actual chemical process occurs at 100 degrees F. The steps: 1. The paper ( glossy or matte) is taken through color developer; 2. Bleach/fixer bath; 3. Stabilizer bath which both stabilizes the paper and washes out the chemicals; 4. Drying. Since the paper is Resin Coated, it dries flat and even. This processing can be done in a machine, e.g. in a

, where rotary tubes transport the film through the baths, or by the photo hobbyist in a

darkroom A darkroom is used to process photographic film, make Photographic printing, prints and carry out other associated tasks. It is a room that can be made completely dark to allow the processing of light-sensitive photographic materials, including ...

setting, using trays for each bath. Current manufacturers of RA-4 Chemistry include Kodak, Freestyle, Rollei, Unicolor and Tetenal as of 2017. The result of RA-4 processing is a Type C, or chromogenic print.

References

External links

Process RA-4 Publication: Z-130
- Official Kodak lab manual Photographic film processes Kodak {{Photo-stub