35mm Reversal Films Are Not Negatives

What is a slide?

A 35mm slide is an individual transparency mounted in a 2″×2″ cardboard or plastic frame. Because it’s a positive, the colors and density appear correct when projected or viewed on a light table. Slides are made from reversal (positive) film, not from negative film.

Reversal film & E-6 processing

Reversal film produces a positive image on a transparent base. Modern color slide films (e.g., Ektachrome, Fujichrome) are developed using the E-6 process, which replaced earlier E-3 and E-4 methods. E-3 used a light re-exposure step and was prone to fading; E-4 used now-obsolete, environmentally unfriendly chemicals, including a toxic reversal agent. E-6 yields stable, vibrant transparencies ready for mounting and projection.

But I shot negatives—how did prints work?

With color negative film, your lab first developed a negative, then made a positive paper print from that negative. With slides, the film itself becomes the positive—no print required for viewing.

Internegatives (from slides)

While slides are not negatives, labs could create a negative from a slide when needed. The common workflow:

1. The original camera negative (for movies) is printed to an interpositive.
2. The interpositive is color-timed and printed to an internegative.
3. The internegative is used to make positive release prints.

For still photography, similar internegative steps let labs make traditional RA-4 prints from a slide when a direct positive process wasn’t used.

Cibachrome / Ilfochrome prints (direct positive)

Ilfochrome (formerly Cibachrome) was a premium, dye-destruction, positive-to-positive print process made directly from slides. Prints were made on a stable polyester base with embedded dyes, known for exceptional sharpness, color purity, and archival permanence.