RA-4 process
In this article, we will explore the various facets of RA-4 process, a topic that has captured the curiosity and interest of numerous people over time. From its impact on modern society to its relevance in history, RA-4 process has played a fundamental role in different aspects of our lives. Through an exhaustive analysis, we will delve into the nuances and dimensions of RA-4 process, exposing its importance and influence in different areas. Likewise, we will examine the different perspectives that exist around RA-4 process, thus allowing a broader and more complete understanding of this very relevant topic.
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RA-4 is Kodak's proprietary name for the chemical process most commonly used to make color photographic prints. It is used for both minilab 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 is carefully exposed to form a latent image 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,[1] 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. Fuji, Agfa, 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 minilab, where rotary tubes transport the film through the baths, or by the photo hobbyist in a darkroom 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
- ^ "Safety data sheet" (PDF). www.adox.de. Adox. Retrieved 10 January 2020.
External links
- Process RA-4 Publication: Z-130 - Official Kodak lab manual
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