E-6 first developer (FD)

Description

The black-and-white first developer of the E-6 process — the step that sets the density of the entire slide. The most critical solution in all of colour chemistry.

Why everything is decided here

The first developer builds a negative silver image; whatever survives it becomes the positive. Longer development means a lighter slide, shorter a darker one — the opposite of the negative process. Half a degree and half a minute are visible to the naked eye.

When it exhausts

Sooner than the other E-6 baths, which is exactly why it is sold separately. The sign: slides come out darker than usual at the same times.

Questions and answers

Can an ordinary black-and-white developer replace it?

No. It contains a silver solvent and a precisely tuned activity; an ordinary developer gives a dark, listless slide.