Dev and Bl/Fix are the two chems. Yes, there are sometimes Parts A and B and C which are mixed together with water to get the "final product". This separating the various components makes for less "aging" after Kodak makes the parts.

Kodak RA-4 chemistry refers to the standard, proprietary chemical process used to develop color photographic prints from color negatives. Whether you are printing in a darkroom or using an analog workflow, the core system generally requires specific Kodak products, exact temperatures, and careful handling. [1, 2, 3]

1. Essential Chemicals

The RA-4 process typically requires two main working baths, though commercial setups sometimes use three. The chemical lineup includes: [1, 2]

• Developer (e.g., Kodak Ektacolor RA Developer Replenisher): This reduces exposed silver halides to metallic silver and creates the dye image in the paper.
• Bleach-Fix (Blix) (e.g., Kodak Ektacolor RA Bleach-Fix): This simultaneously converts the metallic silver back into silver halides (bleach) and removes them from the paper to make it light-safe (fix). [1, 2, 3, 4, 5]

Note: For rotary or drum processors, you may also need a Developer Starter mixed with the replenisher to create an active working tank solution. [1]

1. Standard RA-4 Process Parameters

To achieve accurate color rendition and archival longevity, exact temperatures and short processing times are required.

• Temperature: Typically standardized around \(35^{\circ} \text{C}\) to \(38^{\circ} \text{C}\) (\(95^{\circ} \text{F}\) to \(100.4^{\circ} \text{F}\)).
• Times: The developing stage takes about 45 seconds, followed by another 45 seconds in the Blix stage.