Ferrous sulphate developer for wet plate

Description

A ferrous sulphate developer — the one collodion plates were developed in during the 1850s. It is poured over the plate by hand rather than into a tank, and works before your eyes.

What it looks like

Pour the developer over the wet plate and rock it, watching the image appear over ten to twenty seconds. Stop it with water at the moment you choose: unlike tank development, you see the result and control it directly.

Why iron

Ferrous sulphate develops fast and gives the fine silvery image with the metallic sheen in the highlights that ambrotypes are known for. Organic developers give a different, softer look — the classic result needs iron.

Questions and answers

Why must it be mixed so often?

A ferrous sulphate solution oxidises in air within days rather than weeks. Mix what a shooting session needs.